tekkie

I removed mods from my car and for the life of me I can’t figure out what the problem is. The car ran fine prior to reversing the mods.

i reinstalled the stock headers / exhaust, intake plenum, throttle body / air intake and removed the aftermarket underdrive pulley back to stock. Since that it sorta starts, chokes and then shuts off within seconds, it’s like it’s running really rich and flooding or something.

i can’t find any leaks, changed the maf, put the stock tune back on, tried with / without maf, looked for air leaks and unhooked wires and can’t find any of that. After many hours I am lost. No CEL, no errors in the ecu. I verified numerous times that the black o2 sensors are pre cat and they greys after cat.

i tried the on 60s off 10s throttle adaptation and for whatever reason it’s not showing any adaptations in durametric? Under ecu there is no basic settings tab? Is that only on the 996.2?

ideas? What should I look for in durametric?

Paul Waterloo

Try running with the MAF unplugged, if it runs better, you probably have a vacuum link.

tekkie

already tried, no difference

Imo000

What happens if you try pumping the throttle as if it was a carbureted engine?

DBJoe996

Huh. Spark, air, fuel. Reversing the mods. Back to stock tune.How? Maybe disconnect the negative lead on the battery to reset the ECU. Check the fuse for the fuel pump, and relay. Anything else done? Latest version of Durametric? Is the Durametric communicating with the DME/ECU? Also, it is really important to make sure the intake plenum for the TB is centered and the clamps are tight.

tekkie

I used the software tool to reverse it back to stock, done that before several times so I know that works

did the battery disconnect, no difference
fuse is good, I removed it and then it wouldn’t start at all after the first try, put it back and now it’s doing the same thing so it’s a t least working
the latest durametric and it communicates fine

I may have to remove the TB / plenum and see if somehow it’s getting air around it but I put it on pretty tight so I don’t think it’s that.

if I give it about 25% throttle as I start it the rpm’s go up but then it dies right after that

strange

Imo000

Need to remove one of the coils and check for spark when the engine dies. You will need someone to help or else with this. Do this and report back. If there is spark then do disconnect one of the fuel injectors and check if they get power with a noid light. You will need someone for this too. Also, can you jump the fuel pump relay to make sure something isn't shutting it off after the engine fires?

Porschetech3

Sounds like you got a big ole vacuum leak.

Remove the air cleaner and leave the MAF disconnected. Have someone hold the throttle slightly open and start it while you try to keep it running by spraying wd40 or carb cleaner into the throttle body.

If it revs like crazy each time you shoot a shot of flammable liquid into it, then you have a huge vacuum leak and are getting way too much air for the fuel that's being injected..

tekkie

thanks I have one of those smoke systems for finding leaks so I may give that a try, if it’s anywhere it’s on the plenum because that thing is a pain, especially in the nice cold here lol

dporto

Make sure you check the line(s) on the intake runners (both sides) where the intake plenum attaches...

808Bill

X3 on the vacuum leak. My friend just went through this 2 weeks ago.

jpcork40

my bet is you have a leak at one of the rubber collars that attach the intake plenum.
i have had this exact problem after removing the plenum and 1 of them wasn't lined up correctly.

tekkie

thanks all that is the only thing that makes sense, that intake plenum is a pain but I guess i will wrestle it out again and see if i can sort it out

808Bill

Did you use new gaskets the first time?

Imo000

Don't start taking things apart on a whim. Use a propane torch, brake cleaner or starting fluid to look for the leak. OR fire up that smoke machine.