I am posting a datamaster file for my camaro as listed in signature. Car idled/ran fine after dyno tune, but recently has a terrible idle/won't stay running, and also dies when a/c defrost is on, which it never did before. Checked over car, no vacuum leaks that I can find, good gas, newer plug wires/opti... here is the link, any help would be great
http://www.mediafire.com/file/g2g4tt...82/april10.uni

for comparison, here is the datamaster from when the car ran/idled fine

http://www.mediafire.com/file/iy80tx...sd/test(2).uni

 

You've got trouble codes in both files. MAP on the problem log, hig res Opti signal on the earlier file.

"Bad" file shows left BLM's at 160 both sides, and short terms at 180..... its pouring excess fuel into the engine. IAC gradually opens to hold target idle of 1050rpm, and finally max's out at 160. MAP is around 70kPa, which is why the code is set. At that point is drops out of closed loop, the BLM's are still 160, but the ST's have dropped to 128 (normal for open loop). Idle drops to 700-800rpm. By the end, MAP has risen to 80+kPa. Both O2 sensors are down to 67mV..... running extremly lean. Check your fuel pressure. Also noticed that the MAF flow is about 9.5 gps. In the earlier file, at idle, at the same RPM its reading 14.5gps. May be an MAF problem as well.

"Good" file shows both BLM's at 160... a major fueling problem. But its holding the idle with IAC at 20-30 counts, and O2 sensors are showing it slightly rich. Even the earlier file shows signs of major problems.

Your TPS closed throttle voltage is 0.92.... on the high side... in both files. I thought you would get a code if it went over 0.90V????

 

Yea, actually I had forgot the one file was when I had a bad opti. Opti was replaced shortly after that point. I had thrown high map codes before when it was initially built, and found some vacuum issues, and eliminated that code. There was a point when I was throwing 0 codes... so thats why I am kind of stumped. Also will check the MAF... it really started acting up after a rainy day in the spring... which intially made me think opti, but after reading the data log, I am thinking not. I may go run a data log again to see where it is at today...

Here is the most recent data log. It was idling, but I see IAC was pegged at 160 again...from what it looks like, right bank goes lean, engine dumps more fuel, but o2 stays lean...possibly an exhaust leak maybe? the o2 seems to respond fine throughout the power band, although when driving the left o2 looks twitchy... i'm not sure hopefully an expert can help me analyze it...
http://www.mediafire.com/file/9olvfo...q3/aug2010.uni