Djea3

93 pickup 22re. I have replaced the TPS, cleaned the AF, replaced 02 (federal), checked the fuel pressure, changed fuel filter.
The problem happens apparently when the truck goes to closed loop (after a minute or 5 of warm up). when CEL comes on truck poses power.
I alos rang out the CPU and it seems good to me. Something is happening when Closed loop is initiated.
When driving straight and level CEL sometimes turns off and power resumes. Sometimes at an idle the CEL will turn off on its own. Sometimes I can drive 10 miles an no cel or power loss.
I have checked codes often and showing no codes at all, even when light is still on at start up.
Recently the muffler came lose from pipe but since it is 1 ft behind the catalytic converter I assumed that this would have no real affect. as it was happening before the muffler came lose (it did have a slight leak).
Ok guys I am baffled...what is up with this?

RJR

So when you check for codes, does the CEL blink steadily, or not come on at all? If it's the latter something is wrong in your code checking methodology. Either you're not jumping the right terminals in the diag connector, your jumper is not making contact with the connector pins, or you have a bad wire going to the connector.

The most likely issue based on your symptoms is a knock sensor problem. However, that should set a code (50 something) that you can read.

Also, when you say the truck loses power, how much power are we talking about? Just seems sluggish but still driveable, or can barely move?

Djea3

The CEL was on intermittently. Now it is ON. I have jumped the wires before and no issue. Now the MIL light acts strangely. It sometimes flashes and sometimes doesn't. It seems to be interrupted mid flash. The issue is that the MIL light works great so I am thinking a ECM is bad.