RPMs coming down too fast and stalls. Car does not respond to changes?

[2002_z28_six_speed]

Hired a tuner. He has changed the desired air flow, TC, TF many times over the course of an hour and we cant get the engine to stop stalling after a blip of the throttle.


I have a 408 with a fast lsxrt intake and ls3 tb driven by an xlink. any known issues or thoughts? The engine just dies when I push the clutch in from 2000 rpm or dies after a punch to the throttle. I have put in a lot of honest effort and any internet advice I have found has not been fruitful. The tuner thinks the car should have responded to the values he put in by now.

[APS Luis]

Post up your std un-modified file if you have it

[2002_z28_six_speed]

If it helps sure.

[statesman]

Hired a tuner. He has changed the desired air flow, TC, TF many times over the course of an hour and we cant get the engine to stop stalling after a blip of the throttle.


I have a 408 with a fast lsxrt intake and ls3 tb driven by an xlink. any known issues or thoughts?

My thoughts are that you've chosen the wrong tuner. There's more to tuning than just adding or pulling a bit of airflow.

[2002_z28_six_speed]

My thoughts are that you've chosen the wrong tuner. There's more to tuning than just adding or pulling a bit of airflow.

OK but that doesn't solve the problem. Anyone can make a comment like that.

[statesman]

It kinda annoys me that anyone can call themselves a tuner, and charge people to do a job that they don't know how to do. You've just hired some 'tuner' to waste a gallon of your gas and an hour of your time... and then you have to come into the forum looking for help to try to fix a problem that he should have been able to fix, but didn't... clearly he hasn't got a clue what he's doing. How much did you pay this tuner?

I'll have a look at your log file.

[statesman]

I've looked at your log file and you're not logging many useful parameters, but from what you are logging...

Your trims are having to add a lot of fuel in places (you're lean in places), and you're getting some engine knock (which is never good). The MAP readings are telling me that the whole thing is really unstable, so adding any more air to your TC or TF will probably only make the situation worse.

I would say... go back to the stock tune file and start tuning from there. I'd also suggest logging more useful parameters (logging idle trims would be more useful than logging IAC counts).

[2002_z28_six_speed]

I did some tuning with pat G and none of the files he sent me really made anything better and then I did some tuning with lsx power tuning. did the live session and after about an hour or so it didn't really get any better.

both people should be reconizable names but no results. very hard to get ahold of pat g. havent heard from in a month.

need to close out project asap. can pay someone. just need it fixed.

[statesman]

I did some tuning with pat G and none of the files he sent me really made anything better and then I did some tuning with lsx power tuning. did the live session and after about an hour or so it didn't really get any better.

I've never had to clean up any tune done by Pat G... so I'm assuming he is good.


need to close out project asap. can pay someone. just need it fixed.

How soon is asap?... and are you still running a stock converter on that thing?

[2002_z28_six_speed]

a couple of weeks. ideally. the truck has been in the garage for months. i live in a dense city so driving a stalling vehicle gets annoying.

the vehicle has a manual transmission. the setup is identical to a stock work truck.

[statesman]

To fix the stall, I'll need to fix the whole tune... there's no single table which you can adjust to fix this. Just getting the fueling right will take quite a few adjustments (I adjust fueling at the fueling tables rather than just bending the MAF out of shape). I might be able to get it done in a couple of weeks if you can log regularly.

PM me if you want me to tune for you.

[2002_z28_six_speed]

In the last weeks I was convinced, begrudgingly, to remove some of the aftermarket components from my vehicle.

I removed the aftermarket performance intake and went back to the stock throttle body. The vehicle now idles smoothly and does not stall. And this is with a virtually stock tune with nothing more than a couple of g/s extra in the desired airflow.

It could have been the xlink but ive heard of many people using them with no problems. maybe the ls3 tb screws stuff up. i don't know. maybe the intake is too hard to tune for. beats me. all I know is that I can drive the vehicle now and it isn't stalling. the motor purrs like a cat at idle.

[joecar]

Thanks for posting back.

[statesman]

I removed the aftermarket performance intake and went back to the stock throttle body. The vehicle now idles smoothly and does not stall. And this is with a virtually stock tune with nothing more than a couple of g/s extra in the desired airflow.

That's very unusual... but you were lean in the log you posted, so maybe you had an air leak with the performance intake.

Glad to hear that you found the problem.