Jpack

(Posted here to get higher traffic)

Buddy is on a road trip. History of Car. LS1 heads and cam. Injectors were stockers, hp tuners found injectors too small, went to 30 lbs. car has aftermarket HV fuel pump. Car retuned, ran fine no problems, no SES. Found tb drilled in butterfly. Car ran fine all day yesterday on the highway 85 + mph. Car sat overnight. Started today, no problems, ran 55+ mph on the highway. Got off highway, running side roads, AC on. Car gets cam surge, slight black smoke, dies. Cool car down, runs fine for awhile, then same scenerio. No ses light. Let it sit half hour, runs ok. Then does the same. Again, no SES light. Car is far from home and any help would be appreciated. Thanks in advance.

FORCE_FED_Z

Almost sounds like a fuel issue. Are you broke down on the road or is there anyway you can check fuel pressure?

Either fuel or there might be a vacuum leak somewhere that upsets the car but not enough to trigger the SES light.

Have you tried without the AC on and such? The car might be running to hot with the AC on and disrupting the mixture. If the fuel map was changed in some spots but not across the board it could be causing your dilema.

Jpack

This is a friend on his way to Ak. The fuel pressure was check before he left.
60psi KOEO and 50psi with engine running and the pump is new.
Car was tuned without AC on, thought about this, that the tables might not be right. No Vac leaks, checked all the obvious with him over the phone. I don't like the fack that the TB has been drilled, but that is what this"speed" shop does. Tried to lower the idle, but this hole became an issue in the TB, turned the idle back up to where the shop had it. TB issue will be resolved when he returns. What is odd though, this only happened after he turned on the AC. So that goes back to my thinking about the tables. Now the computr since it learns has now had another curve thrown at it. He hasn't used the AC until today since the car was tuned. I don't want to run a trailer down from IL to AK to get him and his family. This sucks.

FORCE_FED_Z

The TB should never be drilled. Its going to throw off the computer unless you tune especially for it. Not to mention its going to cause turbulance at full throttle...

The more you descibe it, it sounds more and more like a tuning issue. The only other long shot would be that the A/C pump might be heating up putting an extreme amount of drag on the motor causing the symtoms you describe. Once the pump cools off it doesn't drag..but if its blowing cold without a belt squelling or drag then I would tend to rule that out. That amount of drag I would think you would be able to smell it..

Jpack

I think I have diagnosed it. High pressure switch on the ac has a short. This in turn back fed through the TPS. These all share the same +/-5v.

As for the drilling the T/B. Yeah we already know that and have a big issue with the Major well known speed shop. Not to mention their "custom" tune for 500 equals a stock generic tune and slightly modified. This was found using HP tuners and overlapping/ comparing tunes. Our new tuner has since retuned and logged. Fine tuning was done and car was running excellent until this incident. Now the car was done within a couple weeks before he left and had other issues similiar before leaving. Since then, the retune, all has been good. Only issue was the car would die once in awhile on braking to a stop. Problem was the hole in the drilled in the TB and idle was a little low. To compensate short term, the idle was adjusted up and worked ok. Cam is large, big stall, patriot heads for some background on the mods. This car was purchased through LS1tech.