What would cause an ECU to stop "learning"?
Thread Starter
Senior Member
Joined: Sep 2001
Posts: 235
What would cause an ECU to stop "learning"?
I recently reset my ECU by disconnecting the battery when I took apart my intake (Stillen) to clean it.
If I am on the highway and I am getting ready to exit I put the clutch in, apply brakes, and/or steering input my car stalls. This has happened before when I first put in a Fidenza flywheel, but eventually, the ECU "learned" and this stopped happening. I have reset my ECU a few other times in between and it would stall out a couple of times and then it would not happen again.
This time, however, it seems like the ECU is not "learning" this behavior and it keeps stalling. What can I do to remedy this?
If I am on the highway and I am getting ready to exit I put the clutch in, apply brakes, and/or steering input my car stalls. This has happened before when I first put in a Fidenza flywheel, but eventually, the ECU "learned" and this stopped happening. I have reset my ECU a few other times in between and it would stall out a couple of times and then it would not happen again.
This time, however, it seems like the ECU is not "learning" this behavior and it keeps stalling. What can I do to remedy this?
It stalls when you push the clutch pedal IN?
I'd assume something else is wrong and causing it to stall, not the ECU's closed-loop fuel trims (the "learning", so to speak)
Even better would be to hook up to the ECU with an OBD-II scantool that lets you read sensor output, and check both Long Term Fuel Trim values at idle and at higher RPMs to see if they're very close to threshold, which I think is around -25% to +25%? (someone may correct me on this). This would definitely indicate that something is screwed up, whether it's MAF, fuel system, etc.
I guess that kinda answers your question in a way--the ECU will "stop learning" when it learns itself all the way to its maximum thresholds, either 25% more rich or 25% more lean than open-loop parameters. If the ECU ever reaches that point, there is DEFINITELY something wrong with either sensors or the fuel system.
I'd assume something else is wrong and causing it to stall, not the ECU's closed-loop fuel trims (the "learning", so to speak)
Even better would be to hook up to the ECU with an OBD-II scantool that lets you read sensor output, and check both Long Term Fuel Trim values at idle and at higher RPMs to see if they're very close to threshold, which I think is around -25% to +25%? (someone may correct me on this). This would definitely indicate that something is screwed up, whether it's MAF, fuel system, etc.
I guess that kinda answers your question in a way--the ECU will "stop learning" when it learns itself all the way to its maximum thresholds, either 25% more rich or 25% more lean than open-loop parameters. If the ECU ever reaches that point, there is DEFINITELY something wrong with either sensors or the fuel system.
Thread Starter
Senior Member
Joined: Sep 2001
Posts: 235
Originally Posted by spirilis
It stalls when you push the clutch pedal IN?
I'd assume something else is wrong and causing it to stall, not the ECU's closed-loop fuel trims (the "learning", so to speak)
Even better would be to hook up to the ECU with an OBD-II scantool that lets you read sensor output, and check both Long Term Fuel Trim values at idle and at higher RPMs to see if they're very close to threshold, which I think is around -25% to +25%? (someone may correct me on this). This would definitely indicate that something is screwed up, whether it's MAF, fuel system, etc.
I guess that kinda answers your question in a way--the ECU will "stop learning" when it learns itself all the way to its maximum thresholds, either 25% more rich or 25% more lean than open-loop parameters. If the ECU ever reaches that point, there is DEFINITELY something wrong with either sensors or the fuel system.
I'd assume something else is wrong and causing it to stall, not the ECU's closed-loop fuel trims (the "learning", so to speak)
Even better would be to hook up to the ECU with an OBD-II scantool that lets you read sensor output, and check both Long Term Fuel Trim values at idle and at higher RPMs to see if they're very close to threshold, which I think is around -25% to +25%? (someone may correct me on this). This would definitely indicate that something is screwed up, whether it's MAF, fuel system, etc.
I guess that kinda answers your question in a way--the ECU will "stop learning" when it learns itself all the way to its maximum thresholds, either 25% more rich or 25% more lean than open-loop parameters. If the ECU ever reaches that point, there is DEFINITELY something wrong with either sensors or the fuel system.
This started happening after I cleaned my intake filter. Can I clean my MAF sensor? I was throwing the P1420 (not sure) code, the one for the rear O2 sensors. I never bothered changing anything because power/mpg were always fine. I have driven about 300mi. and the code has not been thrown again. Another symptom of my current problem is that I feel like I have more power than ever before.
Idle control valve would require disassembling much of the throttle body, probably taking it off entirely, so it should be possible but it'd be hard...
MAF sensor can be cleaned gently with electrical cleaner or something similar... you can remove the MAF using a suitable tamper-proof torx driver (not sure what size; Sears has a whole set for $30 made by Lisle, that's a bit steep though...)
MAF sensor can be cleaned gently with electrical cleaner or something similar... you can remove the MAF using a suitable tamper-proof torx driver (not sure what size; Sears has a whole set for $30 made by Lisle, that's a bit steep though...)
Thread Starter
Senior Member
Joined: Sep 2001
Posts: 235
Originally Posted by spirilis
It stalls when you push the clutch pedal IN?
I'd assume something else is wrong and causing it to stall, not the ECU's closed-loop fuel trims (the "learning", so to speak)
Even better would be to hook up to the ECU with an OBD-II scantool that lets you read sensor output, and check both Long Term Fuel Trim values at idle and at higher RPMs to see if they're very close to threshold, which I think is around -25% to +25%? (someone may correct me on this). This would definitely indicate that something is screwed up, whether it's MAF, fuel system, etc.
I guess that kinda answers your question in a way--the ECU will "stop learning" when it learns itself all the way to its maximum thresholds, either 25% more rich or 25% more lean than open-loop parameters. If the ECU ever reaches that point, there is DEFINITELY something wrong with either sensors or the fuel system.
I'd assume something else is wrong and causing it to stall, not the ECU's closed-loop fuel trims (the "learning", so to speak)
Even better would be to hook up to the ECU with an OBD-II scantool that lets you read sensor output, and check both Long Term Fuel Trim values at idle and at higher RPMs to see if they're very close to threshold, which I think is around -25% to +25%? (someone may correct me on this). This would definitely indicate that something is screwed up, whether it's MAF, fuel system, etc.
I guess that kinda answers your question in a way--the ECU will "stop learning" when it learns itself all the way to its maximum thresholds, either 25% more rich or 25% more lean than open-loop parameters. If the ECU ever reaches that point, there is DEFINITELY something wrong with either sensors or the fuel system.
I went to autozone for an OBD II scan, but they told me the OBD II scanner doesn't read out this information.
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