Fuel Injected gurus come in
lives in a glass house
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Got traction?
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There are mechanical things that could *possibly, maybe* cause this, that have been discussed, differing fuel pressure, runner distribution, etc.
From an electronic standpoint, there is the possibility of the PCM commanding different fuel volumes for each bank. This is part of the adaptive fuel trim, or 'learning' that the PCM will do. If this is the cause of the fuel difference from bank to bank, it is probably just a symptom of an o2 sensor issue. It is not part of the normal operation of the PCM. You can test this by unplugging the battery for a minute to clear the adaptive memory, and then make a pass.
Hope this helps,
Brian
EFI-Unlimited
From an electronic standpoint, there is the possibility of the PCM commanding different fuel volumes for each bank. This is part of the adaptive fuel trim, or 'learning' that the PCM will do. If this is the cause of the fuel difference from bank to bank, it is probably just a symptom of an o2 sensor issue. It is not part of the normal operation of the PCM. You can test this by unplugging the battery for a minute to clear the adaptive memory, and then make a pass.
Hope this helps,
Brian
EFI-Unlimited
-Mark
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98' cobra
98' cobra
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Bondsman
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No I didnt, the car has been out on the spray before. pulled up unloaded and did a spray pass. We just checked before we put some timing in it for the second run. So I take it that a box intake is no good for the spray?
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Bondsman
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That what I thought. I have heard that if an o2 went it would default to rich
lives in a glass house
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I didn't say that. You tend to see then on more forced induction cars. IMO they seem to work better with the air being forced through them rather than being drawn.
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"you're unloading in third.... just adjust the NOS timer a few miliseconds and you'll run nines"
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Floridaracing.org Tenative Schedulealso check out the Auto-x Event Schedule
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This is my fuck the government movement
Floridaracing.org Tenative Schedulealso check out the Auto-x Event Schedule
"I am and what I do are not a taxable commodity for you to use and abuse" - Me
This is my fuck the government movement
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Dr Dirt,
The adaptive trims are definitely applied at WOT, OL, etc. This is not speculation, it is fact. The cell it is pulled from depends on the calibration. In the case of the A9L, if the MAF and injectors are comp'ed properly, over 4000RPM it won't apply a trim. If using a large MAF/Inj combo uncomp'ed depending on the load scaling, it can pull from %50 load@3000 RPM. The trim learned in these cells take a while to mature, so it will take considerable time to populate them, but it is possible.
Bitemark, GNs-Are-Slow,
In Ford powertrain strategy, anytime a sensor failure is detected, the PCM attempts to substitute a reasonable value for what that sensors reading should be, and operates normally with that substitution. The EPA wants your car running the best it can, even when sensor failure occurs. When o2 sensors are found faulty, the PCM defaults to open loop, ignoring the o2 sensors, and continues to operate normally otherwise. No changes are made to the timing strategy, or otherwise. The problem is that Ford fault detection for o2 sensors sucks. It rarely finds them faulty, and consequently, will operate utilizing a faulty signal, and basing fuel trims on that. This is why Fords typically run rich with bad o2's. Its not the PCM's intention, it just doesn't know any better. Ironically, the A9L seems to be the most fault tolerant of o2 sensors, and unplugging them seems to work ok most of the time.
Brian
EFI-Unlimited
The adaptive trims are definitely applied at WOT, OL, etc. This is not speculation, it is fact. The cell it is pulled from depends on the calibration. In the case of the A9L, if the MAF and injectors are comp'ed properly, over 4000RPM it won't apply a trim. If using a large MAF/Inj combo uncomp'ed depending on the load scaling, it can pull from %50 load@3000 RPM. The trim learned in these cells take a while to mature, so it will take considerable time to populate them, but it is possible.
Bitemark, GNs-Are-Slow,
In Ford powertrain strategy, anytime a sensor failure is detected, the PCM attempts to substitute a reasonable value for what that sensors reading should be, and operates normally with that substitution. The EPA wants your car running the best it can, even when sensor failure occurs. When o2 sensors are found faulty, the PCM defaults to open loop, ignoring the o2 sensors, and continues to operate normally otherwise. No changes are made to the timing strategy, or otherwise. The problem is that Ford fault detection for o2 sensors sucks. It rarely finds them faulty, and consequently, will operate utilizing a faulty signal, and basing fuel trims on that. This is why Fords typically run rich with bad o2's. Its not the PCM's intention, it just doesn't know any better. Ironically, the A9L seems to be the most fault tolerant of o2 sensors, and unplugging them seems to work ok most of the time.
Brian
EFI-Unlimited
Last edited by EFI-Unlimited; Sep 29, 2008 at 11:17 PM.
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Also, something VERY important that hasn't been asked and is commonly overlooked.
Are you shutting the motor off as soon as you lift from the throttle on a N2O pass, then towing the car back to the pits to do the plug inspection? If you are driving it back, and looking at the plugs after it has idled and driven back, the plug readings may not be indicative of what the engine did going down the track. They will be contaminated with what the engine did returning to the pits. This seems to escape most people when it comes to plug inspections.
Brian
EFI-Unlimited
Are you shutting the motor off as soon as you lift from the throttle on a N2O pass, then towing the car back to the pits to do the plug inspection? If you are driving it back, and looking at the plugs after it has idled and driven back, the plug readings may not be indicative of what the engine did going down the track. They will be contaminated with what the engine did returning to the pits. This seems to escape most people when it comes to plug inspections.
Brian
EFI-Unlimited
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Bondsman
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We drove back to trailer, but cant see what that has to do with on side lean and other rich. Does an A9L run injectors on one side idleing and not the other?
I can tell ya how I'd fix it, I'd snatch all that shit off and put a carb on it!
I can tell ya how I'd fix it, I'd snatch all that shit off and put a carb on it!
