PCM relearn after intake change?

[Jefe]

Have heard a rumor that you need to do a PCM relearn after changing the intake on a C5. Also heard this is true if you disconnect the battery. Is there any truth to the rumor?

Jefe

 

[dmrodco]

Its true for all ODB II as well as ODB I computer controlled cars. I left mine disconnected overnite. Worked for me. Good luck

 

[c4c5specialist]

Hi there,
There are a few details that are not widely known in the c5 models, and the 96 c4, about intake changes, and resetting the computer.
While the 84 to 95 models are very quick to learn, they do NOT hold a set fuel trim table that is erased when the battery is disconnected. This is critical when using the 01 and newer intake.
I would suggest, that you go and have your fuel trim tables reset, using a Tech 2 scan tool. This will correctly reset your learned o2 sensor values, and you start with a clean slate, so that correct fuel trims can be established.
Unfortunately, most of the time, people only talk about idle relearn on c5, and NOT fuel trim tables, which the mod affects more.
Allthebest, c4c5

 

[vetu4ya]

c4c5specialist, please clarify what needs to be done to a '99 C5 when the battery is reconnected after a lengthy (winter storage) disconnect period.......thx

 

[c4c5specialist]

Hi there,
Nothing really needs to be done in that particular case, after long storage.
Normally, I only recommend a quick scan with a Tech 2, to make sure that there are not any problems after the long winter.
Other than that, you should be just fine. Your idle may not be totally stable, however, it will smooth out after some driving.
Allthebest, c4c5

 

[Buckmaster]

I didn't do a re-learn after with either of them and my car is fine without issues.

 

[EHS]

I agree with c45specialist, having used various methods.

Using the Tech II to clear the tables is the quickest, particularly if you are doing dyno testing and reconfiguring the car between runs, and you need "splitting hairs" results.

There is really nothing wrong with doing nothing at all, it will just take the car some time to update the tables, based on the modifications.

Quite honestly, for just an intake change (and I was there with the "special procedure," including bowing in each ordinal direction while the water temperature went through 176 F), I would just drive the car like you normally do, and leave it at that. You will not get any codes and the performance will be just fine.

 

[TODD L GRIFFITH]

Idle relearn C5 only

I think it is valuable if you change throttlebodies, intake manifolds or MAF sensors. It's easy if you want to do it.

1. Turn the key to the on position, but do not start.
2. Open up the fuse relay center located in front of the battery and remove fuses #16 and #23. The DIC will start going through alot of messages, not to worry.
3. Turn the key to the off position.
4. re-install fuses #16 & #23.
5. Start the car and let temperature reach 176 degrees minimum.
6. Shut off the car for over 30 seconds minimum.
7. Restart the car and check for codes.
8. Drive the car at different RPMs for 20-30 miles.
You will need about 250 miles for all the fuel tables to be reset.

 

[EHS]

Re: Idle relearn C5 only

....
You will need about 250 miles for all the fuel tables to be reset.

Just curious, how many miles will it take if you don't do the special procedure outlined above?

 

[TODD L GRIFFITH]

Resetting the tables

250 miles is the only one I've read. I don't think it is excact. It depends also on throttle position during that time. They indicated 250 miles of spirited driving at different RPMs.

 

[msiska]

Never had any lean issues with my Halltech T-1c. But when I put the B&B PRT's on, started to get lean codes until I drove about 100 miles. Then they stopped.

 

[my1corvette]

Hi Guy's , I am planning to install a new air intake with two k&n filters and a Mass air flow sensor by Granatelli . I also have a new exhaust made by B&B ,PRT ( to be honest with you, a friend will install these mods since I am too nervous to even attempt a thing like this . )My question is ......will I experience anything different in the beginning ? do I ignore any codes that I may see ,and what should I do, if anything at all after these mods are installed .
As you already noticed I have no idea what I am doing .
Any advise is allways welcome
thanks a million .
John

 

[James Lopez]

C-5 Relearn

I changed my exhsust to the B&B Route 66, with Speedway tips. I didn't get any codes at all. I have a 1998 Coupe.