SLOPONY

All of the "he shoulds" are not going to happen. Just going to have to have it done some where else or buy hp and do it my self.

Jake75

iTrader: (2)

Some friend he is! Hopefully he didn't lock the tune

1FastBrick

iTrader: (17)

Where do you live?

SLOPONY

I am up in the lakes region of Maine.

SLOPONY

So the issue comes down to a lot of thoughts about how this all went down. I went to his shop to have my PCM programmed for a start up tune. I had a 411 PCM in the truck when it was a V6, took that one with me, as well as the 411 PCM that came out of the donor 00 tahoe. He said he couldn't tune either of those and that they wouldn't work. he dug through a box of PCM's and ended up tuning one that had "no tune" written on it in marker. Its a totally different part number than my original and donor PCM.

He wrote the tune on that one, and I have had a start up issue ever since then. he has tried 3 times to get the truck to start and idle.

after thinking about it, It is probably a PCM that he already used credits to unlock and even though I paid for a license, I got one from a previous tune.

I am now wondering if there is a reason he had that PCM sitting around. and I am wondering if there are any compatibility issues with it being a different part number.

1FastBrick

iTrader: (17)

The only replacement for a 411 pcm would be the earlier 4896. If its not one of these, I wouldnt use it for your application.

99-00 application 09354896 = 4896
01-02 application 12200411 = 411

He likely used one that was already licensed and could have had an issue.

GMCtrk

iTrader: (27)

I always had hot start problems with the 2 bar COS tune I had for my turbo set up. Could never figure it out.

Now, with a 1 bar tune, starts are completely normal.

No explanation other than some kind of glitch with the pcm or tuning software.

SLOPONY

Made some progress last night at another friends place. He can't tune but he has a snap on verus and he is a diagnostic genius. We plugged into it, and he came to the conclusion that my "tuner" must have set the desired idle speed, but not adjusted the iac levels to match. The desired idle in the tune was set at 850, but the iac was set to 625, so he bumped up the iac level to match desired idle, and instant fire and Idle. He also tried dropping the desired idle to the same 625 level as the iac and it also fired instantly and idled.

I also discovered that I have the earlier 4896 pcm in it now, and still want to get it re tuned with my original 411.

Atomic

iTrader: (42)

The IAC position is set based on a desired (required) airflow, not an rpm. The pcm adds or subtracts iac airflow (position) to achieve the desired rpm.

For a stock internal truck, keep those values at stock values.

SLOPONY

Aside from the cam, its stock internals. The desired idle speed was changed as well as other start up settings, and not the IAC. So I am going to have the stock start up settings put back in the tune.