Time to get started 4.8 to 5.3

[farmtruc]

remove every vac line from the charger and plug it. the same with the throttle body.
there might be a hose going from the charger to the intake tube or something similar causing a vac leak.

[3DTIM]

OK Just pulled the PVC no help.

[3DTIM]

OK pulled all lines even the gauge line plugged all of them same thing. Runs fine for around 30seconds and the goes up to 2000-2500

[3DTIM]

No way to get to the muffler shop and have new stuff put on. Could this be the problem? No Cat's on it and no mufflers just about 3' of pipe off the headers. Do have the o2 sensors in place.

[3DTIM]

Would it be worth my time and money to get a HP Tuner?

[farmtruc]

Hey Tim, I saw you called today, I'm still out, just checking email and the forum remotely.

There's probably an issue somewhere that is being overlooked, something mechanical or electrical.
If you spend more money and get hptuners, all you're going to find out is that the idle is still set at 600rpms in the calibration and that still wont' fix it.
I know the PCM is the first thing to blame, because it's the least understood.

The pcm is rather simple. The pcm takes in data from sensors, all sensors are inputs, meaning they don't control anything. Things like iac, injectors, egr do things based on input from the sensors, after the pcm calculates what these mechanical devices should do.
The pcm is set to idle at 600rpms. The pcm will have no other reason to idle the engine at 3000rpms, unless there is a bad input.
Or, if there is something physically or mechanically causing the high idle.
ie. vac leak, open throttle blade, bad iac, etc.

Now there could be a bad pcm or an issue with the calibration, but we've tried two different pcms with still the same issue, a high idle. Boith pcms have two different 80e cals.

The iac is told what to do by the pcm, so the iac adjusts idle.
See if the iac is stuck or maybe the park position of the iac is wide open.
Maybe try another throttle body.
Something is causing the iac to hang wide open, the throttle body to stick, or air entering the engine unmetered (but that last example usually surges as well).

If you have a scanner you can check to see what the tps% is at.
It should read 0%.

A good scan tool will show desired and commanded idle, can you get that info?

You mentioned that the engine has already sucked down 2 qts of oil, how long of a period was that?

What did you do to get idle to go down to 2000rpms?

The only other thing I can do as far as tuning is, send you a stock 6L / 80e pcm with only the injectors scaled for, so it will idle (of course there will be codes)

let me know,
allen

[3DTIM]

This PCM is what has got the idle down. Friday night I will get my hands on a good scanner and a scope. I will see if I can come up with a TB don't know about that. TBS is at 0% at idle checked that last time.Looked at the IAC it is new and put my finger up in the hole from inside the TB and it looked to be fully sealed. I will be on the road tomorrow and see if I can find a TB and get a set on GM intake gasket's again. I flat have to get this truck going soon or I am going to have to pull the blower off. The oil was over the last mouth. At idle I am pulling 20pis of vac.

[3DTIM]

There is a small hole drilled in the TB blade could this be the trouble?

[Beatdown Z]

Come on Allen!!! This is the same thing my truck was doing. You sent me a retune with the IAC tables modified. You made changes to make the IAC valve close faster.

At least this is what you/employees told me. But, it worked so try and remember what you did and do it for this guy.

[Beatdown Z]

Here's the message you sent me Allen:

"is the idle any better now? if not, we can lower some tables and not allow the iac to hang so much, i was gonna say the ported tb, but you tried a stock one and did the same thing.

email melissa and request a retune, ask to have the iac idle air table lowered, tell her idle is hanging too long."