I hope no one gets upset, but this is a NON 3rd Gen swap. Folks on this forum have always been very helpful with my problems, and I’ve never owned a 3rd Gen.


I put an LM7 from a 04 GMC 1500 into my Porsche 944. Everything was pulled from the same running truck, the only thing I changed was the intake to an LS6 and made my own headers.

I used PCMhammer and TunerPro to write to the PCM. I used a common OS Id 7603. I removed vats, EVAP stuff, selected manual trans, E fan settings and removed a few MILs. It wrote fine and seemed to be good. I used the stock harness modified per LT1swap.com, and a 18 cuircut fuse/relay panel.

Had a few small hiccups but I was able to get it started. Before starting I had 3 DTCs
P0452 - EVAP, I will need to remove it from the tune
U0107 - lost communication with TAC

I checked Voltage and ground at TAC, and checked grounds at TB. All were good. With the key on the TB would move with pedal movement. After starting car it idled for about 1 min then I shut it off. Giving the car throttle the engine stumbled and then went back to idle. Tried again and it did nothing but idle.

Checked DTCs After that run and had 16 codes.
7 were EVAP and rear O2 sensor related so I will take care of them.

3 were MAF related, MAF was connected but not it in the intake air flow path. That’s human error on my part.

The codes I have to correct

P1516 TAC position performance, through my research I need to ring out all the control wires from TB to TAC.
Possible causes,
no VSS
TCC Brake Switch not connected to anything. I thought it would only effect converter lock up while car is moving?

P0200 Injector circuit malfunction.
Things to check,
12v at each injector, ohm injectors, check circuits with noid light.

P0230 FP Primary circuit malfunction.
Causes,
Bad PCM? Research didn’t give me much info.

I cleared the codes and tried to start the car. No start, it will fire off for a second on starting fluid. FP is 58 at the rail. V is good to all the injectors.

Everything was pulled from the same running truck. I went through the harness and repaired anything that appeared to be faulty. Any connection or splice I made was with bare butt splices, crimped soldered and heat shrunk. Not saying I’m perfect but I really tried to make all connections good.

It seems like DBW is problematic with swaps sometimes. I am considering going to DBC. I have a DBC PCM and TB. I’d honestly rather not after going through the trouble to install this. I wonder if there could be a comparability issue between the TAC/Pedal and the bin file? I really don’t like throwing parts at it, and I don’t have a donor vehicle to try another TAC or pedal.

Any knowledge or advice would be greatly appreciated!

 

Thinking about it I did land a lot of the grounds on the body of the car for the pcm at the same point where the battery ground is landed. I guess it could be possible for that to be an issue? I should place them on the engine block. I do have a large wire grounding the block to the body.

 

The reference grounds for the engine should be on the heads, not the body. That could be a problem

 

Other than that I am at a loss. I guess there could be an incompatibility issue between the bin file I used and the hardware I have. I double checked everything, and the file I used was from an 04 LM7 4x4 which is exactly what I had. I bought a complete truck, started and ran great when I pulled it. I stripped the harness down to nothing and checked everything while doing it. I’ve been burnt on other projects from not being through enough so o really paid attention to everything.

thanks for the reply scooter. I will post back with my findings.

 

I was wrong about the grounds, all of the PCM grounds are landed on the back of the block. All the ring terminals were replaced so I’m confident those connections are good.

I checked all the wires from the TB to the TAC, all rang out good. Is there a way to bench test the pedal or TAC?

I may try using another bin file. I have read of files and hardware not working well together. It’s a long shot but I’m desperate.

 

Another update. After checking every wire between the TB, TAC and PCM everything was good. I figured I would try to start the car again and it fired up so I let it run for about 10 minutes. Give it any throttle and it would start to rev but then instantly stop and go back to idle, sometimes it would have to hunt to get to a steady idle. Go to WOT and it would stumble but stay running. Pulled the steam vent line and filled the coolant system up.

After I shut it off I tried to restart it with no luck. It wouldn’t start.

Plugged the scan tool in after the run and am confused by the codes I have, and the ones I didn’t have.

P0452 EVAP
P0449 EVAP
P0443 EVAP
P0102 MAF (I left it uninstalled again at first, stuck it on right after starting)
P0650 improper voltage level on the output circuit that control the MIL.
The MIL is not connected to 12v yet, it’s wired up I just haven’t connected to a power source.

I am getting nothing for the pedal issue now. Could everything be communicating correctly, but have a faulty piece of hardware?

EDIT:
Went back out to give it another try and to check the codes again. It fired up and ran, same issue with the pedal. No MILs other than EVAP stuff. Could this be some sort of mechanical issue that I am looking past? I do notice the TB blade will not go wide open with the key on and engine off. Not sure if that’s what it’s supposed to do?

 

SOLVED

I disabled anything related to abuse management. Either unchecked it or made the value so high it was out of range. Fired up and it revs no problem.

 

Awesome. Now it's time to go abuse it.

 

I wish! We have about 8” of snow with a nice ice storm happening right now. That’s ok, gives me plenty of time to button everything up so I won’t rush out with it unfinished.

I’ve been a sbc guy my entire life, but these Gen 3 engines are tough to beat.