LS2 won't run (SOLVED)
 

Hi guys,

My car ('88 Firebird) has been in a shop getting an LS2 install, and after many delays they finally tried to start it today. The engine turns but it won't run, it sounds like a distributor engine with a few wires crossed.

The engine was pulled from an '05 GTO by MTI and they installed a cam before shipping it. Any chance they installed it wrong?

The harness was made for the conversion and all sensors are new. Any chance a sensor is bad?

I'm just looking for ideas of where to start. It is getting fuel and spark.

what cam did they put in? did they tune the pcm for the cam? if its a decent sized cam and its not tuned that might be your problem. does it run for a couple seconds then shut off? maybe the vats?

It's the Stealth II cam, fairly mild. The PCM is new with a tune from MTI as well. The car doesn't have VATS either.

I wasn't there when they cranked it, but they said it wouldn't run; it pops a few times and shuts down. I'll go on Monday to see for myself, I'm just hoping to take some ideas with me to help trouble shoot it.

The car may not have VATS but the PCM from the GTO certainly did. Did MTI reprogram the PCM for the cam AND remove VATS?

I'll have to look into that. I thought VATS would just prevent the starter from turning. It's not stopping fuel, so what would the VATS be doing?

The VATS will not stop the starter from turning, the motor will start up and run with the VATS enabled, it will just run for only a few seconds. The VATS will stop the fuel flow 5 seconds after the motor starts.

Thanks for the info. I have a fuel meter installed so we'll be able to check that out.

How hard does the engine run when you first start it with a new PCM? I've read that they don't run well at all until the PCM learns the engine.

Technical answer.... Some run well, some don't...;) ... If your tuner has the tables close, it will start and idle without a lot of bother. What people usually refer to is not that new pcm programs run poorly, they just run better after a few extended start and run cycles and the pcm adapts.

Found the problem: wrong coil packs installed. I had the harness made for the car and I told them they wer the round (Delphi) coils, but the connections were for the square (Mitsubishi) coils. I bought the coils on ebay and they were supposedly off an '05 GTO, but they could be truck coils too. I'm not sure who's at fault.

FYI- the connections are different even though they were made for the same engine. Thanks GM. Basically one pin per coil is reversed causing the coils to fire in the wrong order.

Good to hear that you found it and the car is now running.

I wonder why GM changed the wiring? they are usually so consistent which makes their stuff so easy to work on. I`m disappointed in them on that one :nono: The least they could have done would have been to change the connector so that it would not have plugged in.