LS1 PCM (2002 Corvette) problem - starts and dies in 2 secs

[hIGGI]

Hello

We have LS1 in kit car in this configuration:

- custom wiring, whats not listed, is not present
- Mechanical throttle body with GM 3 wire TPS (working ok, according to EFILIVE software) - no TAC module
- Stock 1 bar MAP sensor - working ok
- no MAF (maf table zeroed out)
- intake air temp sensor - working ok
- no body control module, Vehicle anti theft control set to NONE
- no lambda (disabled)
- no errors

We tried to copy map from our other LS1 equipped kit car , which is running perfectly and no help. Other car has MAF...

We suspect problem is with VATS, but there shouldnt be when its set to NONE...

When trying all different settings, we were able to get PCM into UNSECURED status and then engine was running. Now is PCM back in NOT LOCKED status... and starts and dies...

Thanks for any suggestions...

[WeathermanShawn]

Welcome to the Forum..

Can you post your tune?

MAF has to be disabled in several places to effectively 'kill' it. It is very tricky to do, but you should see a DTC for the MAF.

What do mean 'lambda' disabled?

[hIGGI]

Thanks for welcome and answer ;)

I will try to get tune here, i am not local to car now (i am just speaker for the team).
By lambda disabled i mean O2 (oxygen sensor) disabled. If makes no sense, i will try to get better info about it.

If MAF is not present (nor its wiring) and we have no DTC for it, could it cause whats happening (starts and dies?)

[WeathermanShawn]

Well, as an experiment you could try putting back the stock values in the MAF Table that you zeroed out. If all of a sudden the car starts you know that Table was not disabled. Just putting zero there does not guarantee the MAF was disabled.

Yes, we have seem cars with no MAF at all still attempt to use that Table. And with no O2 sensors the car must be forced into open-loop.

Do your best to post the tune. A car not starting could be many many things.

Good luck.

[joecar]

You have to obtain MAF DTC's for the PCM to ignore the MAF table...

Set P0101,2,3 in:
- C6001 to 1-Trip or Non-Emissions (not Not-Reported),
- C6001 to MIL (gives indication that MAF failed, you can turn off the MIL later).

[joecar]

You can log the VTD and various STATE pids to see what VAT is doing.

And welcome to the forum :cheers:

[hIGGI]

Here is the .tun file

http://rx7.cz/tmp/map.zip

[WeathermanShawn]

Yea that tune is set-up for Closed-Loop (with O2 sensors).

Follow Joecar's instructions of the DTC Processing Enablers. As it is set up right right now it is utilizing the MAF (which does not exists).

You have some work to do to force this car into using the VE Table. Check out the AUTOVE Tutorial for more information..http:///download.efilive.com/Tutorials/PDF/AutoVE Tuning Tutorial.pdf (http://download.efilive.com/Tutorials/PDF/AutoVE%20Tuning%20Tutorial.pdf)

You need to fail the MAF. Thats probably your main problem..

Good luck..

[hIGGI]

Thanks guys, will let u know about progress :)