Ok I know its a newb question but how do I do an idle relearn? Is that just resetting the PCM or what? Just a little confused that's all...

 

Pull the ECM or PCM battery fuse (under the hood) and disconnect the battery for 20-25 minutes or so. Thats one way to do it.

 

k that was the way i knew but i thought that was just resetting the PCM?? am i just trying to make this more complicated than it is? btw will that have an affect on my tune?

 

This is how you do an idle re-learn. Pretty sure this is correct. You could try a search too.

Disconnect the battery for 30 minutes. Then take the positive terminal wire and tap it against the positive battery connector 3-4 times making it spark....then go ahead and screw it back on.

Then:
Start the engine and with the rear tires "blocked" or with the emergency brake holding the car in place (if the e-brake works), put the transmission in "D" and let it sit in place like that idling. 5 full minutes.
((You can use a parking lot cement stump to put the front tires up against if you don't have blocks or your e-brake does not work))

Then:
Immediately after the 5 minute mark, tires still 'blocked" or e-brake set, put the A/C on "max" and the fans on full-blast. 5 minutes.

Then:
Immediately after the 5 minute mark, tires still 'blocked" or e-brake set, turn the A/C "off" and let engine idle. 5 minutes.

Then:
Immedately after those 5 minutes, un-block the car or release the e-brake and hold the car in place by just holding the brake pedal down, A/C still on full-blast. 5 minutes.

Then:
Immediately after those 5 minutes, still holding the car in place by holding the brake pedal down, A/C "OFF". 5 minutes.

Done.

Then, don't turn the car off and go for a 20 minute drive. It also could take up to 50 miles and turning the engine on and off a few times for the PCM to take effect.

 

wow i'm not gonna lie that sounds ridiculous. what's the deal with the A/C switch? and i did a search and all i found was people saying "i tried an idle relearn" but no one actually explained how to do it.. anyway i'll try it although i have no clue why the A/C switch could in any way be involved with how the car idles except that it's a running accessory.

 

When you turn on the A/C the engine gets dragged down, very noticable in any car. So it has to learn how to idle again with that drag. When I first did this like 5 years ago, it worked for me on my 427 stroker. I did have to do it twice though. Did it one day, then did it again like 3-4 days later. Second time worked 100%.

The A/C has something to do with the "banks" in the PCM. I can't remember details and I'm no PCM expert, but when I was given the idle relearn procedure back then they explained it to me.

If you go the PCM/Diagnostics section, they can tell you more about it.

But it seems logical to me that the engine needs to idle in those 2 different ways.
A/C "off" with foot on the brake at a stop light.
A/C "on" with foot on the brake at a stop light.

 

I'd just reset the PCM and let it relearn by itself. Won't harm your tune.

PCM Reset
Turn key on, don't start car
Pull PCM BATT and PCM IGN fuses in engine compartment
Wait 5-10 min
Turn ignition off
Replace fuses

Idle will be grumpy until it relearns, that's how you know it's reset. Beware this will also reset all your emissions readiness tests - so if you're due for an emissions plug in test for codes you'll have to do some drive cycles before testing.

 

ok thanks for the input... i can do engines but the PCM just blows my mind sometimes. i'll try ls6427's method first 'cause i'm curious and if that doesn't work ill just reset my pcm. thanks alot guys!

 

Just out of curiosity, why do you want to do an idle relearn?

 

i ran a thread a few days ago about my car having trouble idling sometimes when i start it but other times its perfectly fine... the consensus was to do an idle relearn but nobody told me how and i forgot to ask. you can read it if you want to its in this section entitled "idle problems but only sometimes"

 

You don't just do an idle relearn procedure. As I listed it, you reset the PCM first, then do the procedure.

PCM resetting doesn't do anything to help the idle. The relearn procedure is what fixes the idle.

And it might not work at all for you, if it doesn't you have to start looking at other things like the IAC valve, dirty MAF, dirty TB, dirty intake, blow by, etc.....

And don't think you will always get an SES light if the IAC or MAF fails. My PCM did not show any SES lights when my IAC and my MAF failed at different times. BUt an OBDII scan showed them as failed. If the idle relearn doesn't work you need to get a scan, and a real scan at the dealership, not with that cheezy one at PepBoys or Advance Auto. They did not work for me, it took the OBDII scanner that the dealerships use. Dont ask me why.

 

alright thanks man i've got some ideas now. ill pm you and let you know how your procedure worked out for me.

 

Below is the idle relearn procedure for an M6 car. A4's are different, A4 cars must do the A/C "on" then A/C "off" steps as listed in the above procedure, with tires blocked.

M6 idle relearn procedure:
Follow these procedures EXACTLY or you will have to start from scratch.

-Insert key into ignition and turn to the "On" position but, DO NOT START THE ENGINE.
-Pop open the engine fuse block box cover and remove the two 10amp fuses from position numbers 16 & 23.
-Your DIC will now display "check" messages for ABS, etc...
-Turn ignition to the "Off" position.
-Re-insert both 10amp fuses for positions 16 & 23.
-Start your engine
-Allow engine coolant temperature to reach a minimum of 176 degrees F and run at this minimum temperature for at least 5 minutes.
-Shut down engine
-Let rest for a minimum of 30 seconds.
-Restart engine - check for DIC error codes (there should be none).
-Drive car for a minimum of 30 miles at varying rpm settings and speeds. PCM will now re-learn and adjust for the new air flow and air temperature at the intake.

 

Here's an idle relearn procedure I found on the net. I missed one step, after you let the engine idle for 5 minutes with the A/C "on" full-blast......you then turn it off and let it idle for 5 minutes with it off. The list I got years ago also had a 5 minute session holding the brake pedal in "D", which sounds logical because you always have that situation during daily driving. Plus, mine is a 1998 PCM so I did the A/C "on"/"off" sessions.

Automatic transmission:
1 Turn off the ignition

2 Restore the PCM battery feed

3 Turn Off the AC controls

4 Set the parking brake and block the drive wheels

5 Start the engine

6 Allow the engine coolant temperature to reach 176 degrees F

7 Shift the transmission selector into the drive range

8 Allow the engine to idle for 5 minutes

9 Turn on the AC controls (Omit for 2000-02 model)

10 Allow the engine to idle for 5 minutes (Omit for 2000-02 model)

11 Shift the transmission selector into Park

12 Allow the engine to idle for 5 minutes (Omit for 2000-02 model)

13 Turn off the AC controls (Omit for 2000-02 model)

14 Allow the engine to idle for 5 minutes

15 Turn off the engine for 15 seconds


Manual Transmission:

1 Turn Off the ignition

2 Restore the PCM battery feed

3 Turn Off the AC controls

4 Set the parking brake and block the drive wheels

5 Transmission in neutral

6 Start the engine

7 Allow the engine coolant temperature to reach 176 degrees F

8 Turn on the AC controls (Omit for 2000-02 model)

9 Allow the engine to idle for 5 minutes (Omit for 2000-02 model)

10 Turn off the AC controls (Omit for 2000-02 model)

11 Allow the engine to idle for 5 minutes

12 Turn off the engine for 15 seconds

 

ok thanks for the help man. i'll be getting to it tomorrow so ill let you know

 

Does this work on a 2011 Chevy silverado..?

 

Does this work on a 2011 silverado..? I'm having problems with the idle control