LS2 Swap fires and dies need help.....

[csouth]

I'm trying to finish up my LS2/T56 swap in my 72 Cutlass and I'm running into serious issues. The pump primes at key on and the motor spins freely.It will fire and idle for 3-5 seconds then die. I had the ECM reflashed, VATS is disabled. I'm using a Current Performance harness which is labled clearly with all connections in place. Using a remote battery and started solenoid so my constant 12v is at the alternator instead of the starter. I rewired the car with AAW universal harness. I have the 12v intended for the ignition coil connected to the 12v ignition on the LS harness, harness grounded the drivers side head and connections from LS harness to fuel pump.
After it dies, I've checked the ls fuse panel and the ones I thought to check off hand(fuel pump, coils, injectors, ecm batt and ecm ignition" are holding 12v. What am is missing here? maybe not enough fuel pressure? I think I would need to buy and adapter to check my pressure at the rails since I'm using billet fuel rails? I'll have my scanner back tomorrow to check for codes. Any thoughts or ideas are greatly appreciated.

[71RS/SS396]

Sounds like vats to me, if you have a noid light check to see if the injector pulse is dropping out, if you're losing the pulse it's likely the vats is not disabled.

[Schwartz Performance]

Your MAF could be backwards, defective, or have a poor connection.

-Dale

[rickpaw]

Your MAF could be backwards, defective, or have a poor connection.

-Dale

^^^ this. What's do you have for codes? My 5.3 with LS1 intake did the exact the same, it was throwing MAF codes. Turned out I had a couple of vacuum ports unplugged.

[csouth]

Sounds like vats to me, if you have a noid light check to see if the injector pulse is dropping out, if you're losing the pulse it's likely the vats is not disabled.

I don't have a noid light, but I can get one. That was going to be my next route of troubleshooting to see if the injectors are maintaining pulse.


Your MAF could be backwards, defective, or have a poor connection.

-Dale

I'll rescan this eve since I have my code reader back. I did check and the MAF is facing the correct direction.


^^^ this. What's do you have for codes? My 5.3 with LS1 intake did the exact the same, it was throwing MAF codes. Turned out I had a couple of vacuum ports unplugged.

I'll rescan this eve and update.....

[csouth]

I wanted to verify the TB was trying to index before start. I removed the TB and place it on the intake where I could watch when I turned the key. The blade moved in the on position. I reattached the TB to the intake and attempted a fire, car starts and runs. Runs rough, but it runs. I do have a code 2138 which is weird because I repinned the pedal for the Monte SS pinout before after finding out it was setup for the TBSS which the motor, ECM and TB originated. There is no response from the pedal to the throttle so I'm not sure what to do about that? The pedal was brand new from GM Parts Direct so I'm doubting its bad.

I also need to figure out the vacuum line routing. I have a catch can that i probably will not use due to lack of mounting location. I'll have to find a setup similar to mine.

[71RS/SS396]

I wanted to verify the TB was trying to index before start. I removed the TB and place it on the intake where I could watch when I turned the key. The blade moved in the on position. I reattached the TB to the intake and attempted a fire, car starts and runs. Runs rough, but it runs. I do have a code 2138 which is weird because I repinned the pedal for the Monte SS pinout before after finding out it was setup for the TBSS which the motor, ECM and TB originated. There is no response from the pedal to the throttle so I'm not sure what to do about that? The pedal was brand new from GM Parts Direct so I'm doubting its bad.

I also need to figure out the vacuum line routing. I have a catch can that i probably will not use due to lack of mounting location. I'll have to find a setup similar to mine.
You have something jacked up in your wiring to the pedal or tb. 2138 will throw it into reduced engine power/limp mode which would explain the rough running.

[csouth]

You have something jacked up in your wiring to the pedal or tb. 2138 will throw it into reduced engine power/limp mode which would explain the rough running.

I think i found the correct schematic for the pedal. Its definitely different than my current pin.

[csouth]

Ok, here is what i came up with: I repinned the pedal to the schematic I found online for the Monte SS(pedal i have), the car would fire and die immediately like before. I moved the pins back to what it was and the car starts and runs again with the p2138 code.
I read somewhere that the ECM flash needs to match the intended pedal and wiring too, anyone know if that's true? If this is the case, my ECM needs a flash that has the same wiring as a Corvette or Monte SS since they have the same pedal schematic

[csouth]

In case anyone comes here to check, the correct tune to pedal so far has made the difference. I put a CTS-V tune on an e67 and swapped the pedal to CTS-V, throttle body now responds when pedal is pressed. Car starts and runs. I will scan for codes and clear them from the tune and reflash later this evening.

[Hugger67RSSS]

Glad you got it figured out Chris, I figured that was the issue. E67's are a pain

[csouth]

Glad you got it figured out Chris, I figured that was the issue. E67's are a pain

Thanks for your help, I appreciate it....