[lildragonlee4]

Here is a puzzling one....my 2003 GT has been to Ford on 4 separate occasions for my service engine light coming on. This is the background on it...it came on and began to flash and my engine instantly bogged down (but didnt stall out) and i lost almost all my acceleration power. I did a diagnostic test on it and said my engine was misfiring on 2 cylinders. I took it into ford and the replaced all the coil packs. I got it back and a few months later it came back on and did the same thing. I took it back in and they replaced the computer in it. Again it came back on and did the same thing. Back in and then they replaced the cylinder heads. It came on again. I had underdrive pulleys on it that were not the best on the market. They brought in Ford engineers strictly to look at my car and they ran a compression test on it and wanted me to replace the pulleys with the original ones and bring it back in for another compression test. I replaced the pulleys but had to move down South so i never got them to run a compression test on it. Since then my service engine light comes on from time to time and will flash and bog down ONLY when my RPM's go over 3000. And i have also noticed that the light will go off for a few days and out of the blue come back on and stay on for a few days or weeks and then go off again. I have no idea what ti could be. The only additions I have added a cold air intake and a bigger throttle body and plenum. If anyone out there has any suggestions please throw them my way!!!

[mcqueen]

Did they replace the spark plugs? Not to get too simple about it, but you've checked to be sure all the spark plugs are good and correctly gapped, right? And are you using a recommended brand for your car?

[03SonicBoom]

Power breaks down to 3 basic things; Compression, Fuel, and Spark. The first time you take it in they should be able to tell you which of those 3 is the issue.

If it's not the plug, I would say you have a partially clogged injector. Swap the injectors on cylinders 1 & 2. Then check the code next time it comes on and see if it moves to cylinder 1 missfire.

[mcqueen]

Originally Posted by 03SonicBoom Power breaks down to 3 basic things; Compression, Fuel, and Spark. The first time you take it in they should be able to tell you which of those 3 is the issue. If it's not the plug, I would say you have a partially clogged injector. Swap the injectors on cylinders 1 & 2. Then check the code next time it comes on and see if it moves to cylinder 1 missfire.

+1

[Sixxer 708]

Originally Posted by 03SonicBoom Power breaks down to 3 basic things; Compression, Fuel, and Spark. The first time you take it in they should be able to tell you which of those 3 is the issue. If it's not the plug, I would say you have a partially clogged injector. Swap the injectors on cylinders 1 & 2. Then check the code next time it comes on and see if it moves to cylinder 1 missfire.

+2

[RedFury013]

Originally Posted by 03SonicBoom Power breaks down to 3 basic things; Compression, Fuel, and Spark. The first time you take it in they should be able to tell you which of those 3 is the issue. If it's not the plug, I would say you have a partially clogged injector. Swap the injectors on cylinders 1 & 2. Then check the code next time it comes on and see if it moves to cylinder 1 missfire.

+3