So a month ago or so the car started acting funny. Once it would go into closed loop it would sputter be real down on power and run rough. First i tried the MAF but that didnt help. I hooked up a scanner and there were no codes and as far as i could tell things were kinda normal (however for some reason the software would freeze up all the time and show the same values for the remainder of the spreadsheet)

I have spread sheets and screen shots from when i was scanning it.

Then whenever I'd work on it, unplug the battery, etc. The car would run fine for the first drive, then the second drive it would have the crappy running for a little bit and be fine. Then the third drive it was just all crappy. It worked like this everytime.

So i got fed up and took it to the shop, car ran fine the whole way there and the shop called and said it was running fine when they drove it around too. he said that the scanner shows the MAP sensor isnt responding correctly and thats all he can see but the car is running fine. So I figure if the MAP sensor isnt working right i mine as well replace it.

Cut to today, over $200 down on this so far and the car started running crappy on my way back from the DMV, it ran like that for a few blocks through norristown and then ran fine the rest of the way home. SO im assuming that it will run crappy the next time I drive it.

All I Can think of right now that is wrong is the gasket from the header to the y-pipe is blown and im going to replace that right now.

Honestly Im at the end right now, I will be going back to school greatly in the hole and im considering cutting the insurance to the car. If anyone can help me in anyway to help figure out what the hell is wrong that would be greatly appreciated. Thanks

 

How much driving have you done? Has this been in the same tank of gas? Been buying gas from somewhere different. Could be as simple as bad gas? Drop 2 cans of dry gas in it.

New I'd start looking at the ignition related parts.

Few things I'd check: Ingintion module. I just went thru this with my car. Would idle fine, as soon as I drove it it would run horrible and was throwing about 8 codes. Turned out my Excel ing. box went bad.

Coil, could be going bad.

Plug wires. Some times once the heat from the ehuast soaks into them they will start arcing. Try driving the car at night and if it starts acting up pop the hood and look for the acrs.

 

http://www.mainstreamtopics.com/foru...p?showtopic=78

Here is a no start diagnostic specifically for the LT1 that is great. it will help you diagnose the fuel system and/or the ignition components that are bad or on their way out. Try pulling the map and cleaning it with electronics cleaner if you haven't already replaced it.

When you say running crappy do you mean like a misfire, a shake or just slow. It could be the fuel pump on its way out as i have had a friend's car do the same thing and eventually die leaving him stranded somewhere. Check fuel pressure when it is running fine and then when its crappy. look at the short and long term fuel trims with a live data scanner while its running poorly. That will show a lean (misfire) or rich condition.

The ICM could be overheating, maybe try shoebox's mod with the spacer. How is the voltage when the car is running poorly? I also saw a car barely move on acceleration when the alternator and battery where on the way out. Only occured when they both were hot. As soon as they were cool, started right back up. Good luck!

 

I've spaced the ICM from the block, that was a problem a long time ago. I checked the wires tonight when the car was running rough and saw no arching. I will try to do the no start diagnostic but i have little time now that im back at school.

the conditions are like running on a few cylinders on and off. Thats the only way i can describe it.

My mechanic friend was outside when it was running crappy so i called him over to drive it and it ran crappy for a minute then ran fine, as soon as he was gone it ran horrible the rest of the night, its like the car sent from satan or something.

I think im cutting the insurance to it because I dont necessarily need a car now that im at school, it would be horribly convenient but for now theres no point since I cant seem to figure out whats wrong with it. I guess from here on out ill just try to diagnose the problem but I gotta say, this car is giving me no hints in any direction right now

 

If you've got an intermittent problem like that, it should show up in the data logs. If you can send them to me in .xls or .csv format I will take a look at them.

 

Brandon, check all your ground wires and studs. Sounds like something may be loose.

Also EGR and the canister purge can cause poor running at times. Coolant temp sensor, an ignition problem as well. There are numerous items that can do that. See if you can scan and send it out like Fred said.

 

Ive got some spreadsheets from the last time I scanned that Ill see if I can find.. the problem with that is half the data is kinda useless because for some reason it always freezes up when im scanning

edit: heres one

http://www.mediafire.com/?dwc4mlsummd

let me know if anyone has any problems opening that up and I will try to fix it

If you are able to see it, youll notice its frozen up in the beginning and then starts reading again and then freezes up for the rest of the sheet. thats why im having trouble scanning it and i dont know if thats a car problem or the software/cable problem