Runs well cold, feels like it is down two cylinders when warm

[The Foos]

Okay. Here is the history on this problem.

For months now, my car has run like crap under high engine load/ wot conditions. At times, it will misfire. But it was inconsistent. One day, it would run great, the next it would have this problem.

I suspected a vaccum leak and did a pressure test on my entire intake (turbo to head), and I do have a leak in my intercooler, but not a huge one. Plus, considering that the problem was erratic, I figured that couldn't be it.

Then yesterday, as I was driving, my car suddenly bogged. I was just cruising, and the engine started to brake. As I came up to a light, the idle fell to around 500 rpm, and it died. It started back up and I was able to drive it, but it felt like it was down 2 cylinders. I had to reset the idle higher and give it a lot of gas to get it to go anywhere.

So, I took the plugs out and replaced them (the old ones looked good, looked like it has been running on the rich side, but good). Started it up, and it ran just fine for the first couple of mintues (until the computer tried to go into loop with the o2 sensor, I assume). Then the rpm dropped to 500 again.

Here is what I have checked so far: replaced spark plugs, checked coil pack, checked ecu.

Last time I checked the check engine code, it was for o2 sensor, fuel system code. I plan to check it again, but I don't have an o-scope handy or a good multimeter.

Anyhow, I suspect the o2 sensor, but I was wondering if anybody has seen these simptoms before and has anyother ideas.

Thanks fellas.

Scott

 

[BISHILVR]

well, the proper way to diagnose the problem is to get the car to run bad, at that time you should remove the plug wires one at a time to see if any of the plugs are loosing spark, if not then the next thing would be to remove the injector connectors one at a time and check them for an injector signal to see if you are loosing injector pulse to one or two cylinders. It actually sounds more like an ecu problem to me though

 

[The Foos]

I found the problem today. It was the transistor pack.

I checked the spark on all the cylinders, and I found that I was down cylinders 2 and 3. Coil was fine. I had a spare t pack sitting around, so I swapped that out and the problem cleared right up.

Just FYI

Scott