I put an LM7 into my Porsche 944. Everything was pulled from the same running truck, the only thing I changed was the intake to an LS6. I have a build thread, but being specific to the PCM I will probably get more help here. I hope you folks don’t mind me posting this here too.

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. As I type this it really sounds like a voltage problem to the injectors. EDIT, 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 help or advice would be greatly appreciated!

 

Something just popped in my head. I landed 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.

 

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?

The bin file I used was from gearheadefi. There were multiple files from the same year truck, the one I used was from the same truck as mine. Maybe I should try another file?

 

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?

 

Went back out to fire it up again, started up and idled fine but had the same issue with the throttle. Shut it down and again no restart. Fuel pressure stayed between 58-60. Checked codes and it only had EVAP related ones.

Something I do notice, with the key on and engine off, the TB blade will not go wide open. Is that how it should be?

No codes is really throwing me off. Could there be a mechanical issue I am missing?

 

Problem could be the maf. If it is not in line, you open throttle, maf does not measure more air coming in, so you go really lean. Either unplug maf or get in in place before the TB

 

Also, move your spark and injector grounds to the heads not the block.

 

Ok I will move those grounds to the heads. Last start up the MAF was in place and the problem still occurred.

The TB doesn’t go WOT with the engine not running. Everything I have read says it should. Could that be a problem with the APS or the TAC?

 

I moved the grounds for the coils to each cylinder head. And I found that my relays did not have a good ground. After doing those 2 things the engine now starts everytime.

I was not correct about the TB. It does go to WOT. I barrowed a better scan tool from a friend. The scan tool does see absolute throttle position. So I am confused, the PCM is obviously seeing what the TB is doing for the scan tool to see it.

Reading through 10year old threads Simone had a similar problem that ended up being abuse management. That does sound like it could be this because it almost seems like it’s hitting a limiter. I’ve sent PMs to members, but some haven’t been active for years.

here is a video of it running

 

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.

 

Nice job. It is amazing how grounds get so many people.