I recently finished my ls1 swap in my 87 squarebody. I put an ls1 out of an 01 camaro. I rebuilt the entire motor and put a .600 lift 231/242 cam into it. Stock ls1 intake with headers. Had the computer shipped out to mail order tuner. First start up didn�t run well, wouldn�t idle correctly and barely stayed running. It would start and then die. If you gave it any gas it would stay on but then coming back down to idle would want to die. It also ran super rich. We pulled all the plugs and all we�re black except cylinder 7. Cleaned all the plugs and put them back in. Found out there was a nipple under the MAP sensor that was snapped off so we put a screw in it to cap it off. Tried to start it again and it�s still idling like crap and doesn�t wanna run. Any suggestions?

 

Sounds like you need a good live tune. Mail order tunes are fine for stock engines, but once you start swapping cams and things, a real tune is in order.

 

Do you happen to have a full exhaust on this or just open headers? Could be a bad tune or back feeding the o2s and they're just dumping fuel. I've seen it both ways.

 

I�ve heard this also. It�s just headers right now, last night we added exhaust after it on one side. Didn�t get a chance to fire it up yet

 

Have you checked the compression on your #7 cylinder. I would replace that map sensor.

 

haven�t checked compression on it yet but the map sensor is brand new.

 

There's your problem. Fresh air backflowing into the headers, throwing the O2 counts way off.

 

would that cause all my problems?

 

It would cause super rich A/F ratios

 

Usually when someone starts off a post with the first sentence saying a swap was finished, I assume it has exhaust! LOL But, yeah, it could be be from having no exhaust and the fresh air is throwing off the O2 sensors, but that would only be if it was run long enough to get to closed loop. When the engine is cold, the PCM doesn't use the O2 data. You could just unplug the O2 sensors until the exhaust is on it and see if that helps the situation.

 

Put exhaust on. Figured out #7 fuel injector was clogged so we got a new injector and put it all back together. Fired it up and it idled great and ran great! Throttle response was good and #7 header was same temp as the rest. So we fixed that. We continued to let it run and revved it up a couple times and it started to not idle and run bad. We turned it off for a little and checked a few things. Tried to fire it back up and it wouldn�t run for crap and won�t idle barely staying running. Opinions?

 

Get a real tune from an actual dyno tuner.

 

The O2 sensors kicked in, and with open headers caught whiffs of fresh air and sent the PCM into full rich since it was seeing so much air.