Sudden rough-running problem
 

I was driving my '93 FD around town a couple of days ago when the check engine light suddenly came on and the car, while still running, was acting very strangely. It would run o.k. as long as the boost gauge was firmly planted in vacuum, but would almost die if manifold pressure got anywhere near positive territory. I immediately limped the car home where it then sat for a couple of days until I could look for any obvious things like vacuum lines that might have popped off or electrical connections to sensors that might have come loose. No such luck with finding the obvious answer. To further frustrate matters, when I started the car the check engine light was no longer illuminated and the car ran fine. Do any of you have a possible explanation of what might have been occuring and what sensor if any might need to be replaced? Thanks in advance for your help.

Dan

did the car buck at all?

Turn off car.
Jumper TEN and GND.
Turn key to ignition, but don't start the car.
Watch the engine check light blinks.
Long blink is tenths, and fast blink are ones.
so if it do long blink once, and fast blink six times, you have code 16.
Check the code against the code by searching the forum, or manuals, or some website.

then you will know what problems your ECU is sensing.

reza

MAP SENSOR!!

Yes! But only as the manifold pressure approached 0. While in vacuum it seemed to run normally.