1995 Escort 1.9 L engine code #538?

Hey!
A friend at work has an intermittent problem with his 95 Escort. When the check engine light comes on, the car runs rough and has a dramatic decrease in power. When the check engine light is off, it runs fine. He has checked and replaced vacuum lines and also found an engine error code # 538.
He looked up the code and found a few different descriptions:
1. Insufficient RPM change during engine run test.
2. Invalid cylinder balance test, cylinder ID problems.
3. Brief wide open throttle not sensed during test.

Any ideas?

Thanks as always...

Joe

My book says #538 is:

Brief wide open throttle not sensed during self-test or operator error.

So Dave, what do you think? Maybe test operator error? But what would explain the intermitted rough running engine? Maybe it's another problem?
Thanks,
Joe

So Dave, what do you think? Maybe test operator error? But what would explain the intermitted rough running engine? Maybe it's another problem?
Thanks,
Joe

As part of the engine code diagnostic test, you are supposed to "blip" the throttle open quick (step on the gas for a second), and then turn the steering wheel a half turn. If the operator does not do this, the computer says hey I didn't detect the throttle open. If you go through the whole sequence of testing the way they describe in the manual this code should go away, at least it did for me.

As with reagrds to the rough engine, I don't have anything to add, other than being sure you check all the vacuum lines thoroughly, give a thorough tune up, etc. I'm troubleshooting an idle problem which mysteriously cleared up by itself, making me wonder if it was a bad batch of gas.
Good luck.