| RobSJ, Tim, maybe DaleB, Detonation, Timing, Octane, and OBD II …
- Click HERE for Original Thread
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| xcel |
Hi RobSJ, Tim, DaleB, and anyone else that may be able to assist:
___I need a favor from you three if possible/practical … It has to do with using 87 vs. 91 octane fuel in the MDX. Given the Pilot and Odyssey have engines producing the same HP at slightly higher RPM’s while using the recommended 87 octane, the only way to find out if the MDX is fine with the same is to hook it up to the OBD computer and check the timing advance using both fuels at similar day time temperatures. I know the higher summer temps is when higher octane fuel is best used for pre-detonation concerns but summer is unfortunately almost a distant memory. What I would like to know is if the X’s timing retard from the knock sensors is still well within band while using 87 octane? Is it comparable to the Pilot’s advance using the same? Someone with the Hand held OBD II Computer connected should be able to see the difference if the atmospheric conditions where similar on a vehicle driven with Premium unleaded vs. the same or similar vehicle driven with Regular unleaded as it should show a different advance in the table, correct? This is where DaleB may come in. Since he is very close to Rob’s dealership, maybe he could run his MDX’s tank down to practically empty and give it a gallon or two of 87. Run it up to Rob’s place for a quick look at the Computer and see what the table looks like. Next, he could fill up the rest of the way with 91 Octane unleaded premium and run up to Rob’s shop for a second look within a half hour so that atmospheric conditions would be similar for a good comparison. I would like to see the output when its 95 degrees as this would be the true test but I have a feeling that the two tables will be so similar as to make 85 degree and below driving with 87 Octane the std. I do not know how the EGR would be affected with one vehicle being colder/warmer than another or the gas tank vapor return affecting the results while on an almost empty tank vs. a full one but maybe someone could help me out with an explanation worthy of this forum. I don’t even know how much of this older technology is on the X in the first place?
___In any case, Tim, if you could run this experiment with one of your dealerships X’s or Rob run this test independent of DaleB’s X, I would be most appreciative. If anyone else would like to add to my thoughts as to make the test more scientific, please feel free to add whatever you can. If you happen to own an OBD II computer of your own, please feel free to perform the test on your own X and please post the results back here ASAP. It may take a bit of analysis from those that understand the output but I am sure there are enough car junkies in the forum to take the data and dissect it properly …
___As for me, I know a bit about small engines but the information on OBD II, detonation, and knock sensors in a real automobile engine all comes from what I have found on the net in the last few hours … If the terms I have used above don’t make sense, please correct the misstatements but please follow through with the tests if at all possible.
___Good Luck and thanks for any and all replies …
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| DaleB |
Before I start running back and forth with different grades of gas, let Rob weigh in on the problem.
He may be able to do a predictive analysis based on what he knows about how these systems operate.
He works in a dealership, and the logistics of arranging times for him to do checks like that I am sure would be somewhat difficult.
A more revealing test might be running a Pilot and MDX on a dynamometer and see how much peak HP is affected by running different grades of fuel in each. |
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| donsev |
Wayne,
If you have a Palm Pilot you might be able to find out for yourself:
Pocket Logger Engine Data Analyzer
There are many other types of OBDII kits, including those that plug into the serial port of a laptop - this one just happened to be recently mentioned in the October Car And Driver. |
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| remery |
Wayne,
Like you I live in Illinois where they blend ethanol in our gas. California still uses MTBE although I believe they will be switching over to ethanol in the next few years. Thus I doubt that a detonation test using gasolines having different blending components would have the validity you are looking for since they may be other factors affecting the results. Trust me, you will notice a performance degradation with 87 octane versus 93 in the MDX in Illinois but not that noticeable with mid grade 89 octane. If you do a search, I did some empirical analysis a year ago that showed I got slightly higher mileage in the summer with 89 octane as compared with 93. I attributed the difference to the 93 octane having more ethanol giving it a lower average energy content per gallon. If you drive 15K miles a year and average 17 mpg like I do, fueling with 93 octane versus 87 octane Illinois blended gasoline will cost $175 a year more. Hardly worth worrying about if you are about to pay $40K for a MDX. |
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| DaleB |
quote:
Originally posted by remery
Wayne,
Like you I live in Illinois where they blend ethanol in our gas. California still uses MTBE although I believe they will be switching over to ethanol in the next few years. Thus I doubt that a detonation test using gasolines having different blending components would have the validity you are looking for since they may be other factors affecting the results. Trust me, you will notice a performance degradation with 87 octane versus 93 in the MDX in Illinois but not that noticeable with mid grade 89 octane. If you do a search, I did some empirical analysis a year ago that showed I got slightly higher mileage in the summer with 89 octane as compared with 93. I attributed the difference to the 93 octane having more ethanol giving it a lower average energy content per gallon. If you drive 15K miles a year and average 17 mpg like I do, fueling with 93 octane versus 87 octane Illinois blended gasoline will cost $175 a year more. Hardly worth worrying about if you are about to pay $40K for a MDX.
Keep in mind that regular burns slightly more efficiently (more BTUs per gallon) than premium in most cases. Our 76 stations have gone off MTBE in exchange for ethanol. I am sure others will follow. Getting rid of MTBE far outweighs any advantages it may have had. |
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| xcel |
Hi Donsev:
___I own an 800 series Cassiopeia (Windows CE based since it was free) and would love to see the timing advance movements using the two different fuels at various RPM’s. This could put my questions as well as all of the threads dealing with Premium vs. Regular unleaded to rest rather quickly. If I owned an X, and had a Data Logger type setup (under Windows CE or on the laptop under XP Pro) outputting the results, I think I could answer my own questions. I still have a feeling that the timing adjustment with differing fuels is negligible given the Pilot’s and Odyssey’s peak outputs matching the X’s while running on regular unleaded. It is hard for me to imagine that Honda would purposely impose this recommendation for an Acura yet let the Pilot owners drive happily and merrily along while using less expensive fuel and receiving the same peak outputs for heavy load towing, drag racing, mountain climbing, or whatever?
___In any case, I would love to see a timing advance trace in 95 degree F + type temp’s (worst case scenario) with the two fuels and than see the same timing trace with a Pilot using 87 Unleaded. I spoke with a home brew tech this morning about this thread. He mentioned that it is usually at higher ambient temperatures when knock sensors retard timings and this follows along with what I read last night but he had no idea how the MDX was tuned to begin with.
___Remery, the proof is in the results as you have already shown but it’s the cost at the pump that gives me concern. I have a 3 mile longer distance to get to the Marathon with $0.03 - $0.06/gal cheaper Regular unleaded than the Speedway down the street and I drive it. I could care less if I am driving the Landscape truck or an S series Mercedes, needlessly throwing away three or four bucks at every gas stop for Premium unleaded needs some investigation but I can be a little on the anal side too. My wife already is moaning because of the inordinate amount of time I have spent in the Acura MDX forum already ;)
___Good Luck and if anyone has the Data Logger type of capability, I would love to see it. I am also attaching a sample trace of timing at idle to ~ 3000 RPM for an unknown automobile from the Data Logger site. This would really be neat to see on an X for sure!
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| TheRobSJ |
Even Honda's PGM-FI scan tool, as expensive as it is, doesn't update quickly enough to make it easy to really track spark advance/retard accurately. My own Snap-On Scanner is a little faster, but it's cartridges are only up to 2000 MY import vehicles. And for the kind of money required to update, given the fact that I almost never use my import cartridges, forgive me for not wanting to update every year.
A great tool would be a graphing multimeter that tracks real time, and not just takes samples from the PCM, such as the Snap-On Vantage. They're only around $1500 with all the toys. Anyone want to buy me one? A Fluke 98 II would also be great. Of course there are much cheaper ones out there, but the Vantrage can track two different parameters for you such as the knock sensor and the spark control,
Honestly, I think you guys can get away with 87 octane. Of course, it will be more susceptible to to ping which of course will reatrd the timing and reduce power. Seeing as how the hot season is coming to a close, and I can't image you all bought these things to tow all the time, your chances of pinging are low even with 87 octane.
Of course if you're dipping into the throttle all the time for whatever reason (full load of people, towing, driving like a maniac...whatever) you'll feel the difference between regular and premium.
Rob |
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| remery |
Wayne,
Nothing stays the same. For awhile Speedway around me was charging the same price as the majors or sometimes even higher. In the past month, they have been charging 10 cents less. Today, I filled up on Speedway premium that was only 15 cents more than regular. You might see a brand price inversion between the two stations and then you won't have to drive as far next time!;)
Dale,
You guys might not be as happy about switching to ethanol when you see the cost you folks have to pay to ship ethanol to CA from either the Midwest or from foreign producers...and then there's supply/demand considerations like Marathon withholding supplies to the Chicago market giving us the highest prices in the country...and the occasional midwestern drought. But then when did CA ever follow rational economics.:rolleyes: At least in Illinois it lines ADM's and our farmer's pockets.:cool: |
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| DaleB |
quote:
Originally posted by remery
Wayne,
Nothing stays the same. For awhile Speedway around me was charging the same price as the majors or sometimes even higher. In the past month, they have been charging 10 cents less. Today, I filled up on Speedway premium that was only 15 cents more than regular. You might see a brand price inversion between the two stations and then you won't have to drive as far next time!;)
Dale,
You guys might not be as happy about switching to ethanol when you see the cost you folks have to pay to ship ethanol to CA from either the Midwest or from foreign producers...and then there's supply/demand considerations like Marathon withholding supplies to the Chicago market giving us the highest prices in the country...and the occasional midwestern drought. But then when did CA ever follow rational economics.:rolleyes: At least in Illinois it lines ADM's and our farmer's pockets.:cool:
I am not saying ethanol is best answer, but MTBE is the definitely the wrong one. Supposedly there are studies under way to produce ethanol in California, it's a huge market it would be crazy not to. MTBE is to be gone by the end of 2003.
http://www.energy.ca.gov/mtbe/ |
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| TheRobSJ |
Oh yeah...MTBE sucks alright. Ethanol isn't too nice either. Too much concentration of it can prematurely weaken rubber fuel parts like hoses and injector seals.
I saw the post about checking on a dyno. Realisticly, that's the best way to see the difference between regular and premium. They're kinda hard to find around here. But in the Smog Check II areas in CA, you can find one.
Rob |
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| xcel |
Hi All:
____Remery, I watch the gas prices closely as my driving distance requires it. $1.37.9 in downtown Waukegan, IL. Gurnee is from $1.38.9 (Marathon on Rt. 41 and Stearns School) and up currently and is about as cheap as it gets near me. In Schaumburg and downtown Chicago, there are stations on main intersections still at $1.67.9 + for regular unleaded. Oasis' at both Ogden and Lake Forest on I-294 are in the $1.53.9 range. In Joliet and in Braidwood, IL., I have seen $1.43.9 for the last 2 days. $1.49.9 was charged for literally month's prior in Braidwood in particular. I-55 at Rt. 6 and Rt. 30 are at $1.43.9 and $1.46.9 although that was maybe a week ago when I looked over to see what they offered while driving past.
___And back on the topic … I have located some great Windows 98, ME, 2000, XP SW and HW interface cable tools for OBD-II automobile diagnostics. About the best for a very reasonable price complete kit comes from a small web business by the name of OBDII Automotive Scan Tool and Virtual Dashboard. $122 for a single interface, $142 for two and $162 for 3 of the std. automobile interfaces. The 3 interfaces are needed for various brand automobiles as explained below:
ISO - for European, Asian, Chrysler
VPW - for General Motors
PWM - for Ford
___My only problem is that the author does not list if the SW and interface are compatible with the 2001/2002 MDX's, 03 Pilots, and of course my 03 Corolla. I will E-Mail him tonight to see if he has updated his SW for the later vehicles or not. There is a review of this SW and HW package from the automotive site called Bat Auto Technical. Great site for us wannabe mechanic types ;)
___There is also an even cheaper setup with description called OBD Automotive Diagnostics with a $76.00 charge for the interface cable and free SW. It has most of what anyone would need but is not as professional in both its feature list and interface.
___As for a dyno tests, I figure that this may be overkill in this instance. A simple Timing advance charted at various RPM's (1000, 2000, 3000, 4000, and possibly 5000 steady if you can find a smooth and straight stretch of road without chance of a speeding ticket or collision/accident) graphed using Premium and Regular should suffice. Since you have intake temps, you may be able to run on separate days as long as the points are close. If both fuels show the same advance, you can bet that at high RPM, you will still have all the power on tap for whatever you want to use it for. Only in higher ambient temp operation would I suspect to see the knock sensors retard the timing significantly and I would suspect this with either fuel in some regard.
___In any case, a simple test such as the one I suggested should help figure out if the Premium vs. Regular discussion is even needed without all the guess work. Rob, would you care to comment as to the MDX's ISO std. based OBD II or has it been proprioritized once again?
___And finally …yesterday morning, I knew nothing of the OBD II and today, I am getting rather excited about hooking one up and seeing what it can do on quite a few vehicles, not just an X …
___Good Luck to you all.
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| TheRobSJ |
Propioritized? Now there's a word! It's such a great word, that even I, the great pillar of knowledge that I am, don't know it.
OBD-II is standardized to a degree. Hooking up scanner and using "Generic OBD-II" mode will still allow you to see trouble codes and read live data on SAE standardized sensors/switches. Manufacturer specific things, that set trouble codes for the block of numbers reserved for "manufacter's discretion," may not show up. I'm not enitrely sure on this, for I've always had the proper scanner. But if I am right...something like the VTEC solenoid, IMRC solenoid, and definitely things like data for the A/T, ABS, and VTM-4 will not show up. I'm curious about it now too. Might just have to experiment this week.
Rob |
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| DaleB |
One thing a dyno test will do for sure is tell you if the power goes up on a Pilot when running on premium fuel.
Not expected.
And power will go down on an X run on regular.
Expected, but not to a great degree. |
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| xcel |
Hi DaleB:
___Dyno or not, it goes along similar lines of the fastest processor in your PC. Most cannot tell the difference between a 2.0/2.1 and a 2.53 GHz P4 yet I can show anyone the difference using multiple benches. I can also make a Tualatin based 1.4 GHz Celeron feel faster than an OC’ed 2.8 GHz P4 but that is for another forum ;). Anyway, I can almost guarantee the same holds true from the perspective of a driver behind the wheel of an X. The 20 HP increase touted for the new 03 is going to be absolutely undetectable except for someone with a stop watch. I have a suspicion the same holds true for someone that uses Premium vs. Regular although Remery says he can feel the difference. With the Acura statements that you may have a decrease in performance while not using Premium fuel may only come to light when its 95 + degrees outside and you are pushing maximum load/RPM/HP. At that point, the Pilot will suffer possibly as much since the engine computer will retard that timing to avoid knock irregardless of which vehicle you are running at the time. Its just a suspicion of mine that the two engines being identical in HP and within 1% of Torque (undetectable) while using two different Octane fuels that the X is going to perform so similarly w/ Regular unleaded to be for all intents and purposes the same. Even if you were to lose 5 HP on the top end vs. the Pilot, you than must ask yourself if you have ever used 240 HP either acutely or for an extended period to make the $1,000.00 worth it to you for that small amount of time when you have your foot mashed to the floor and running at 5300 RPM? The only good that can come of that is that you have premature engine damage from beating the hell out of your X and the same would apply to the Pilot.
___I cannot wait for someone to hook their X up to one of the OBD II SW/HW wonders and tell us what is truly going on with the timing advance using the two different fuels is all. Wouldn’t that be a kick if they show the almost exact same trace across the entire range of RPM’s or if the Regular unleaded trace matched the Pilot’s? If so, would most here still throw $3.00 to $4.00 away at each and every fill up? Back to the question at hand … Is there a difference?
___Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| DaleB |
I wholeheartedly agree one would be pressed to find a difference. I think yours as well as RobSJ's analysis comes to the point where using premium on an MDX only provides an edge when driving under greater loads and/or under higher temps.
But you are also suggesting maybe that same edge could be seen in a Pilot running under those same conditions.
So maybe the Pilot's owner's manual should have a statement about running premium fuel, inverse to the one in the MDX manual.
For me I will probably continue to 'mix' the fuels at times depending on my driving 'mission'.
And keep using a PIII 750Mhz processor until my Dell warranty expires in Feb. It certainly is up to the task for a good 90% of the software I ever use. |
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| xcel |
Hi DaleB:
___The Pilot spec’s do!quote:
Premium unleaded fuel increases engine torque and is recommended when towing above 3500 lbs. Maximum towing capacity is 4500 lbs. for boat trailers and 3500 lbs. for all other trailers. Premium unleaded fuel is recommended when towing above 3500 lbs.
___As for your 750 MHz Dell, keep it until it dies or until it doesn’t run the SW you use on a daily basis ;)
___Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| DaleB |
I didn't know that about the Pilot's specs!
Then we've come full circle. I think your analysis is sound.
It might be interesting to see the plots.
But the other thing that has me curious is the supposed difference in power curves (profiles) between the two vehicles. Like where peak torque is developed. Can this be the result of something other than mechanical changes (i.e.; cam grind/valve timing)? |
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| wmquan |
Honda specifically says that using premium in the Pilot's engine increases torque under some fairly stressful conditions -- namely for towing.
That's pretty consistent with the experience of a poster -- I forgot if he was here or on Edmunds. He had complained for some time that his MDX had trouble passing on inclines. After a while, he revealed he was using regular gas. He tried premium, and he claims that his incline passing ability was notably better and he didn't have any more complaints. |
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| xcel |
Hi Wmquan:
___Your reads may place the Pilot in the same predicament? At the same amount of HP on tap, I am not sure? I have been reading through Edmunds Town Hall - MDX (you are very active over there) for the past two months and saw a few posts in regards to the acceleration issue dealing with the X’s transmission programming? The Torque curves between the two vehicles must be different since they do have ever so slightly different spec’s but the peak HP (240) and torque (242 vs. 245) being the same? I have yet to read a full blown review on the Pilot in a car mag but how are the acceleration and top speed figures as seen in the ¼ mile traps vs. the X? Are they similar? I have seen a few posts showing times all over the map depending on the mag, time of year, and who knows what else?
___Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| wmquan |
quote:
Originally posted by xcel
The Torque curves between the two vehicles must be different since they do have ever so slightly different spec’s but the peak HP (240) and torque (242 vs. 245) being the same?
The torque curves, as documented by Honda and Acura in the vehicle's in their brochures (there's a prior thread that goes into the specifics, but I forgot where it was), are indeed different. The Honda begins producing more torque at lower RPM's than the MDX. |
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| xcel |
Hi Wmquan:quote:
The Honda begins producing more torque at lower RPM's than the MDX.
___With more torque produced at lower RPM’s in the Pilot, this is even more reason to wonder why Acura recommends Premium for the X and not the Odyssey or Pilot? Regular unleaded actually has more power?? to the gal (faster burning anyway) than Premium unleaded and if the X’s engine controls can adjust for the faster flame front to avoid any detonation properly, the X may actually get better mpg while using the lower Octane fuel? Than again, preventing detonation while advancing the timing towards it maximum could theoretically give more HP while using Premium unleaded. It’s the same HP and Torque listed for the three vehicles that make me wonder. I am stepping out well beyond my knowledge of the subject however …
___Any mechanics or dealers out there care to hook up an X or Pilot to one of these OBD-II boxes and have a look at the timing advance curves?
___Thanks again and Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| wmquan |
quote:
Originally posted by xcel
With more torque produced at lower RPM’s in the Pilot, this is even more reason to wonder why Acura recommends Premium for the X and not the Odyssey or Pilot?
It is possible that Honda has added improvements to the Odyssey/Pilot engine that are simply not in the MDX's yet. Which is why the MDX requires premium. |
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| xcel |
Hi Wmquan:
___What about the 02 Odyssey which uses the same engine as the newer 03 Pilot? What has me worried is the new 260 HP from the same engine in the 03 MDX. Honda may have forced the issue (Premium not just a recommendation but mandatory) with a higher compression ration and a more aggressive timing advance :( Both of these improvements are not a good compromise for longevity of the automobile IMHO.
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| TheRobSJ |
What is the engine code for the Pilot? The MDX is J35A3 I believe. If the Pilot's code is the same, then there are NO mechanical changes to the engine.
A TL has a J32A1, and the Type-S has a J32A2. There's different parts on a Type-S engine. So if the Pilot has different parts, that would explain why there is a difference in fuel requirements. Is the compression ratios the same?
Rob |
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| xcel |
Hi RobSJ:
___Yes, the compression ratios are the same in all three engines.
___Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| remery |
quote:
Originally posted by xcel
...more reason to wonder why Acura recommends Premium for the X and not the Odyssey or Pilot? ...
How attractive is a minivan that burns premium? I know there are a few lead-footed soccer moms out there but not the norm. The Pilot will likely appeal to more cost conscious customers who don't want to spend the extra money for a MDX or want more space. All three have the same compression ratios which is the usual criterion for octane so my guess is marketing demographics. With all the discussion in this thread and others about the cost of premium gasoline versus regular this is a very plausible reason for the differences. It's human nature to focus on the small while losing sight of the large myself included. I'll not bat an eyelash at spending $2K for a new set of golf clubs but losing a $2 golf ball on a water hole rips at my heart! Go figure!:cool: |
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| TheRobSJ |
I bet it's all a difference in fuel maps then.
Rob |
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| turbo2ltr |
If anyone is in the Phoenix area and would like to do octane comparison tests with the PocketLOGGER, we could arrange a loaner unit.
Regards,
Mike Montalvo
digital tuning, inc.
www.pocketlogger.com |
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| donsev |
quote:
Originally posted by turbo2ltr
If anyone is in the Phoenix area and would like to do octane comparison tests with the PocketLOGGER, we could arrange a loaner unit.
Regards,
Mike Montalvo
digital tuning, inc.
www.pocketlogger.com
Hey, how about a group buy? (I assume this means that the PocketLOGGER does work fine with the MDX OBDII port? Do you know what info it *can't* access?) |
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| TheRobSJ |
Why are the sample rates for alot of the latest cars so low?
Rob |
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| turbo2ltr |
Sorry no group buys.
Honda's have always been slow. The OBDII protocol only specs 6 samples a second. Anything above that is a 'bonus'.
Regards,
Mike Montalvo
digital tuning, inc.
www.pocketlogger.com |
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| turbo2ltr |
In order for me to tell you what it can't access, you have to tell me what you think it can.
There is a list of possible parameters in our FAQs. I've never seen fuel pressure supported in any car. All the other parameters typically coincide with the equipment on the car. i.e. you wouldnt be able to log airflow if you dont have an airflow meter.
Regards,
Mike Montalvo
digital tuning, inc.
www.pocketlogger.com |
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| xcel |
Hi Turbo2ltr:
___That was fast … Did Donsev send you a link or do you happen to visit the hundreds of various automobile forums just for the heck of it ;) In either case, do you think you could port your SW and HW scan tools to a Windows based portable including CE or Pocket PC or even a more capable Windows based Laptop under 2000 or XP? Secondly, you might as well make the OBD-II HW and cabling USB compatible while you are at it … That could very well be a market segment you may truly want to own.
___What do you think of this threads content to date? You have to be an astute car guy to build upon an OBD-II type product so we may as well hear your opinion on the extremely similar engines and the fuels used (87 vs. 91) for similar Torque, HP, mileage, and longevity of the vehicle using the two different fuels. I sure hope someone in Phoenix takes you up on your offer so as to look at the timing curves at various RPM’s with the two fuels in their own X …
___And back to the nitty gritty … If you have a trace of a particular parameter, how do you know what the trace is supposed to look like vs. what the factory intended? Is that what the centerline in some of the plots represent or are you supposed to simply check that the sensor runs its full range from lets say + 1.5 to – 1.5 V and than view its output as a base line? Are you supposed to compare the plot at a particular RPM to what the factory spec’s say it is supposed to be? I know I am not making myself very clear here since I am not an automotive mechanic so bare with me.
___Let’s say we measure the timing advance in an MDX at 1000, 2000, 3000, and 4000 RPM w/ Regular unleaded and than again with Premium unleaded on the same day within a few hours of each other. Similar atmospheric conditions if possible in Phoenix on a cool January evening or a hot July afternoon hypothetically. If the two plots were not an exact match (they will more than likely be very close but I can’t see even two MDX’s running Premium unleaded being a perfect match), what would you be looking for to say that one timing advance plot meets the factory spec or the other one is being forced beyond factory spec with the X’s computer making the adjustment? Which one is right? Since I am digging for answers, given the two scenarios (MDX with Premium and MDX with Regular unleaded), what other parameters do you think would be helpful to measure if the X truly needs Premium unleaded or not? Would you consider the O2 sensors before and after the Cat converter to give you an idea of the efficiency or possible power degradation of the X while running with the two different fuels? The Hi and Low fuel trim settings possibly? Would you need to see a Honda Pilot’s timing plots with Regular Unleaded to compare against the MDX with either fuel? Is there a way to look at the knock sensors output using the two fuels to see if it is in fact changing the timing directly? Maybe that would be a parameter to actually watch if we can? Does the knock sensor actually do the work of calculating an engines timing retard or advance or is it another performance parameter with a knock sensor only taking charge when an engine is running up against its destruction limits and more drastic measures are needed to save itself from the driver or fuel used? Any ideas would certainly help in this regard.
___I can only hope I made some sense to you in the last two paragraphs …
___Finally, a special thanks to you for taking the time to visit, post, and hopefully answer some of our questions in the next day or two.
___RobSJ, could you please explain to me what a fuel map is?
___Good Luck to the both of you …
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| donsev |
Pssssst....Wayne....I thought *you* sent Turbo2ltr the link.....
No matter, we welcome his involvement and looks like this could lead to some very interesting discussions.
quote:
Originally posted by turbo2ltr
In order for me to tell you what it can't access, you have to tell me what you think it can.
I was asking more to see if you felt that it would be able to answer some of Wayne's questions more so than any of my own questions. |
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| turbo2ltr |
I occasionally check website refferals and saw someone posted a link here.
We have no plans to port the software. The market is saturated with laptop based OBDII programs. WinCE devices wouldn't allow us the low level control of the serial port that we need without using additional hardware and defeating our exclusive byte timing feature. A USB interface would probably double the cost of the unit because of the hardware needed. The cable would have to simulate being a USB Host. I've looked into it and you need quite a bit of hardware to create a USB host.
According to one of the posts, the engines do have knock sensors. In that case, I would assume it's there for a reason. I'm pretty sure most other honda engines do not have knock sensors. Since this one has one, it's probably there to protect the engine from clueless people that just put whatever crap gas is available and go drive up a mountain.
Running turbocharged cars I *always* run the highest octain available. But sometimes not even 94 is enough..
The "DSM" guys (Eclipse/Talon) use the logged timing curve to see if they have knock. They look for smooth curves and total timing between 17 and 24 degrees. Total timing may differ on your car, but you should still be looking for smooth cures. If the curve is jagged or falls off, then it's pretty safe to assume there is knock and the ECU is pulling the timing.
All this assumes WOT runs. If you never go WOT, you probably would never get knock on lower octane. Intake air temps do effect the possibility of knock. The higher the temp, the more easy it is to knock. But the changes in weather temp probably would not affect it much as they dont swing that much. On a turbocharged car, intake temps can vary hundreds of degrees depending on intercooler efficiency. Again, effects of intake temp would only really be apparent under WOT or high load.
In the MDX/Pilot case, load would be a bigger factor in he possibility of knock. Seeing the comments about using premium while towing would make sense.
Everything being the same (esp. compression ratio), the thing that would effect recomended gas grade would be more aggressive timing maps. Cam grind would probably be more likely to affect the differences in the the torque curve.
There are no reference values for a particular parameter. You basically have to understand what it's telling you. There are basic behaviours that a particular parameter should follow, but thats about it.
> ___Let’s say we measure the timing advance in an MDX ...
Hmm..I don't think there is a right and wrong here. I outlined above how you could extrapolate knock out of the timing curve.
Fuel trims and o2 sensors are typically used to check fuel delivery. They would not really change significantly between octanes.
For some reason, a Kncok parameter was never written into the OBDII spec. Why, I dont know...I guess you can blame our freindly neighborhood SAE. So unless there is a way for the factory tool to read the knock sensor, we are out of luck.
Fuel map: (or any map) is basicallty a 2D or 3D lookup table. i.e. there are maps programmed into the ECU. The ECU read the sensors and looks up the matching value. (assuming these engines are speed density like most hondas) the ECU will look up RPM, TPS, and the MAP sensor on a table and get injector on time. Or it will look up RPM and MAP on a timing map and get how much timing to have. The knock sensor would then have the last word. The circuitry in the ECU would determin if there is knock (based on the signal from the knock sensor - which is basically a microphone), and how much, then adjust the base timing value (from the map) to what it thinks would eliminate knock.
Regards,
Mike Montalvo
digital tuning, inc.
www.pocketlogger.com |
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| xcel |
Hi Turbo2ltr:
___Now that was a post!quote:
All this assumes WOT runs. If you never go WOT, you probably would never get knock on lower octane. Intake air temps do effect the possibility of knock. The higher the temp, the more easy it is to knock. But the changes in weather temp probably would not affect it much as they don’t swing that much.
___First, I assume WOT means Wide Open Throttle. If the above statement is true, if you don’t run your X anywhere near WOT, you would more than likely not have any problems running any grade of commercial gas in the MDX than?quote:
Everything being the same (esp. compression ratio), the thing that would effect recommended gas grade would be more aggressive timing maps. Cam grind would probably be more likely to affect the differences in the torque curve.
___With cam grind out of the picture as far as Premium vs. Regular unleaded is concerned, a slightly different intake manifold, header design, or more than likely a more aggressive timing map is probably what we are after as far as differences between a Pilot/Odyssey and the MDX’s engine performance with the two fuels? Rob, is there a way you can see the tables using the scan tools you have available to you and than compare them with those picked off a Pilot from a Honda shop for example? I still believe running an MDX while watching the timing advance curves at the various RPM’s with either Premium and Regular unleaded would be the easiest way to tell the differences between 87 and 91 Octane given Tubo2ltr’s reply? Does anyone know an enthusiast MDX owner in Phoenix that would like to take Mike up on his offer? Inquiring minds most certainly want to know ;)
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| TheRobSJ |
The only way I could think of to determine if there's a difference in PGM-FI maps, is to run the Pilot and MDX under the exact same condidtions. Like on a dyno. Then, using a scan tool, compare the injector pulse width and spark timing. If the two do indeed have the same powertrain and fuel/timing maps, then those numbers should be identical. This would also be the way to see ithe difference regular and premium gas has...other than the power measurement from the dyno.
But there's nothing in the service manual about the maps. Maybe in the ENGINEERING specs, but good luck getting those. I'm sure a tuner that knows their way around the Honda PCMs could figure them out as well.
Rob |
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| renov8r |
You could use a dyno to load the vehicle then match up the traces from the injector pulse width and timing to reverse enginer the programming emperically. It would be difficult and prone to errors.
Tuners do in fact regularly poke around in the PCM to extract the various parameters that are burned-in. It is far more reliable & time efficient. You need the schematics of the PCM and a listing of the values that burned into the PROM(s), as well as which values cannot vary. Typically the PROMs themselves yields alot of this info when it is plugged into a programming module. Unfortunately, the 'field programmable' portions of the PCM are very limited and the data is stored in such a way as most of the PCM has to be rebuilt. In contrast to the early days of digital engine controls, one used to be able to pop out a single PROM with all the timing and fuel delivery info ( as well as EGR, torque converter lock-up, shift points ...). I suspect that with the "tuner talk" and relatively deep pockets of some Pilot & MDX owners aftermarket PCM are just around the corner...
To Wayne's original question/idea: Contact the companies that MANUFACTURE aftermarket PCMs.
http://www.autoserve.8m.com/
http://www.hondata.com/index.html
http://www.hondaecu.com/
They should have the tools to extract EXACTLY the info you want! If they "have no plans" to worl on the MDX/Pilot/(Oddy?) point out the forums here and for the the others AND offer to set them up with some willing 'test vehicles'. Odds are they'll come around... |
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| remery |
Wayne,
This discussion about octane and engine computers chip has really been interesting but is this all you need to consider? I am assuming that you work at Braidwood and not Zion so your daily commute approaches 200 miles which over a year is close to 50K. At that rate you would use up your MDX warranty in one year and would put on 150K miles in 3 years. $40K/3 = $13K+/yr. This dwarfs any fuel premium that may exist. Unless you have recently won the Illinois lottery, that's a bunch of dinero to spend on commuter transportation. As much a I love my MDX and can cite it's many virtues, purchase cost is not one of them. I would consider not only the variable but the fixed costs in your decision if I were in your shoes. What would a MDX cost annually over it's lifetime versus some other vehicle that would meet your needs. I use to work for Amoco so I know my way around an octane barrel, but I don't think that's all you need to be considering. |
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| xcel |
Hi Remery:
___I do commute daily to the Braidwood facility and it’s a monster but fortunately or not, this is for my Corolla LE. I car pool with two other guys so that brings me into the 25,000 mile/yr. range since we do not always drive together. All 3 of us have hopes of Zion reopening someday and with the SO, you stay where the wife wants or you don’t keep the wife :( The X will be my wife’s and she only has a 15 mile commute (round trip) just off I-94 at Rt. 137. I wouldn’t dare think about driving the X that far on a daily basis but it would be nice ;)
___In any case, I plan on purchasing one of these engine management HW/SW packages for the X but that will probably be quite some time from now. I have some White papers on the 10 largest myths in regards to engine Performance tuning and another on fuel theory to read tonight during lunch so hopefully this will help with the discussion at hand. One item so far … Torque and HP are always equal at 5250 RPM? One is derived from the other mathematically. I am still reading on flame fronts and velocities, how Octane controls these parameters, and Timing advances in these two articles since this line of questioning has now become a hobby of sorts whether I like it or not …
___What I am mostly interested in with the X is a safe and reliable SUV. The X just about leads the pack in those regards. Owning a very reliable Toyota Previa for as long as we have (10 years - 176,000 mile now), we still need a vehicle for the kids and that third seat no matter how useless will fulfill the B-Day parties, soccer outings, church get togethers. That and the X will fulfill our camping/vacationing type needs as well as looks so darn cool :D
___Now if it can do it all while living on 87 Octane … than it’s the vehicle to own IMHO. I still have concerns about Acura increasing the Compression ratio (very bad move Acura!) w/ a longer connecting rod or redesigned wrist pin location thus forcing Premium unleaded in the 03 but we will all have to wait to see what is in store for us future 03 owners.
___Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| remery |
| Now that makes more sense so let's get down to the real economics. Have you asked your wife yet if she thinks she is worth the extra $0.20 per gallon? Spousal contentment is part of a vehicle's life cycle cost!:) |
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| xcel |
Hi Remery:
___I already told the wife she will be using Regular unleaded and I used the Pilot and Odyssey as examples. Even if the engines are not quite exact matches for whatever minor reason, she doesn’t know this and I did show here the “Premium is recommended” clause in the MDX brochure. I am the type of guy that will save his pennies and the dollars will usually take care of themselves. That should just about explain the jist of my line questioning but having seen the fuel threads literally hundreds of times while using the search function, it is time to get to the bottom of this. Tapping the Engine computer is about the only way I can think of for average layman to do it so let’s hope for concrete answers one way or the other …
___I forgot to mention that our 1 yr. old Golden Retriever will more than likely own a portion of the cargo area. I just need to figure out a way to separate the luggage and necessities from the dog without lugging her cage with us? My youngest is already talking about taking her with us to the Outer banks of North Carolina next year …
___Good Luck
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net |
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| mdxxxx |
| This thread is very educational. Thanks for the knowledge transfer....:D |
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