Total computer reset procedure
#1
11-27-2011, 08:26 AM
Total computer reset procedure
So, I had a little skirmish here with a member here on how to properly reset ECM error codes - pull fuse out ot disconnect the battery.
Guess what. Turns out to be, there's an interesting procedure for complete ECM reset. Sort of combination of ECM de=powering, and driving cycle right after.
Is it applicable to TCH's HSD? Don't know. I know, "check hybrid drive" message comes up if battery was discontinued. And it needs to be cycled out.
So, I'd seriously caution against this procedure on TCHs. But we do have other cars too, so it's generally interesting. Never heard of it.
Not a day without learning something new
Notes:
The reset procedure is billed as a ‘cheap fix’. It does often give good immediate results, however if there is something wrong with your car (any number of issues as listed above) then over a 2-8 week period the car will likely return to its original state.
The reset procedure removes all mean values stored by your onboard computer that control engine timing, fuel use etc. As you continue to drive the car, the stored values ‘average out’ to best suit the engine condition.
If your car has for example a leaking intake manifold gasket or broken O2 sensors, the readings are quickly going to become ‘corrupted’ with incorrect information. This can lead to the engine running too rich or too lean (check your sparks for evidence). Within a short period of time the car will return to rough idle as the underlying problem has not been fixed. That said – the reset procedure can reset values that are no longer applicable. You may have replaced something on the car (e.g. Catalytic Converters) thus causing a sudden change in normal engine running. The readings stored over 10-20 years will suddenly not suit you recently modified car. The car will however read new values in and average out over time. The Reset procedure simply speeds that process up.
The long and short of it is that this procedure can sometimes fix rough idle and transmission timing and seems to improve the cars performance. However with existing underlying issues as outlined above – it won’t be long before the problems return. Perhaps this procedure could be used if you’re trying to sell your E32 ;-)
Procedure:
1. Disconnect battery cables, first negative, then positive.
2. Cover and protect the battery posts! Leave no potential of a battery short circuit.
3. Turn ignition to position II.
4. Connect both battery cables ("SHORT") for at least 10 minutes. This step drains a capacitor in the ECU/TCU. (Covered the battery with a thick, dry shop towel to prevent actually shorting the battery! – careful of arc welding in my back seat! As the battery was in place, and the cables aren't that long, you could use a very long Craftsman screwdriver and two small vice-grips to actually clamp the negative and positive cables to the metal shank of the screwdriver.
5. Wait 10 minutes - then ignition off, key out.
6. Reconnect battery positive, then negative.
7. OBC says "PPPP", reset time. Start and idle the engine for 5 minutes, then off for five, then out for a drive.
8. Now, with the car in lowest gear (one or two depending on your make), accelerate until at least 5000 rpm is reached. Allow the car to slow to idle, and then repeat two more times. Let the car idle for 5 minutes. All Done!
9. Idle should smooth out over 10-12 miles; shifts should be immediately smoother.
Guess what. Turns out to be, there's an interesting procedure for complete ECM reset. Sort of combination of ECM de=powering, and driving cycle right after.
Is it applicable to TCH's HSD? Don't know. I know, "check hybrid drive" message comes up if battery was discontinued. And it needs to be cycled out.
So, I'd seriously caution against this procedure on TCHs. But we do have other cars too, so it's generally interesting. Never heard of it.
Not a day without learning something new
Notes:
The reset procedure is billed as a ‘cheap fix’. It does often give good immediate results, however if there is something wrong with your car (any number of issues as listed above) then over a 2-8 week period the car will likely return to its original state.
The reset procedure removes all mean values stored by your onboard computer that control engine timing, fuel use etc. As you continue to drive the car, the stored values ‘average out’ to best suit the engine condition.
If your car has for example a leaking intake manifold gasket or broken O2 sensors, the readings are quickly going to become ‘corrupted’ with incorrect information. This can lead to the engine running too rich or too lean (check your sparks for evidence). Within a short period of time the car will return to rough idle as the underlying problem has not been fixed. That said – the reset procedure can reset values that are no longer applicable. You may have replaced something on the car (e.g. Catalytic Converters) thus causing a sudden change in normal engine running. The readings stored over 10-20 years will suddenly not suit you recently modified car. The car will however read new values in and average out over time. The Reset procedure simply speeds that process up.
The long and short of it is that this procedure can sometimes fix rough idle and transmission timing and seems to improve the cars performance. However with existing underlying issues as outlined above – it won’t be long before the problems return. Perhaps this procedure could be used if you’re trying to sell your E32 ;-)
Procedure:
1. Disconnect battery cables, first negative, then positive.
2. Cover and protect the battery posts! Leave no potential of a battery short circuit.
3. Turn ignition to position II.
4. Connect both battery cables ("SHORT") for at least 10 minutes. This step drains a capacitor in the ECU/TCU. (Covered the battery with a thick, dry shop towel to prevent actually shorting the battery! – careful of arc welding in my back seat! As the battery was in place, and the cables aren't that long, you could use a very long Craftsman screwdriver and two small vice-grips to actually clamp the negative and positive cables to the metal shank of the screwdriver.
5. Wait 10 minutes - then ignition off, key out.
6. Reconnect battery positive, then negative.
7. OBC says "PPPP", reset time. Start and idle the engine for 5 minutes, then off for five, then out for a drive.
8. Now, with the car in lowest gear (one or two depending on your make), accelerate until at least 5000 rpm is reached. Allow the car to slow to idle, and then repeat two more times. Let the car idle for 5 minutes. All Done!
9. Idle should smooth out over 10-12 miles; shifts should be immediately smoother.
#2
01-23-2016, 07:22 AM
Re: Total computer reset procedure
I used this method to pass smog. I charted it 4 times. My finding are that you need to drive 15 minutes and drive into a smog that has no lines. Do not turn off the car, open the hood and wait for them to ask you to turn off the car, tell them you have leg problems and don't want to get out. They will reach across to plug in module. and the car will restart, run for a minute or so, then pass. Have cash to pay fee, exact is best, and be on your way.
About 5 minutes later the CEL amd IMA turn back on simultaneously and you drive for another year.
Of course there is no guarantee this will work, but it has 2 years in a row for me. And it seems that with the incredible stupidity of our smog laws that it is an equitable solution, seeing as my car is NOT causing much in the way of smog.
About 5 minutes later the CEL amd IMA turn back on simultaneously and you drive for another year.
Of course there is no guarantee this will work, but it has 2 years in a row for me. And it seems that with the incredible stupidity of our smog laws that it is an equitable solution, seeing as my car is NOT causing much in the way of smog.
Last edited by NevadaJ; 01-23-2016 at 07:23 AM. Reason: typo
#3
01-24-2016, 08:27 AM
Re: Total computer reset procedure
The readiness monitors need at least three drive cycles to set a "pass" condition for a smog check. Mind letting us know how you managed to bypass that with this procedure? All you did was re-set the system ECU parameters, not override the readiness monitor for a smog check.
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