Dwight Johnson

On first start up after an ECU rebuild on my 1988 911 the engine sounded like it was running on 5 cylinders. After several starts and days the problem is still there. Any ideas would be very appreciated. This car is like loving the beautiful girl that is playing real hard to get. thanks, Dwight

ivangene

did it run on 5 before, why was the ECU rebuilt, waht tear car and stock or modded

irobertson

I don't see how the ECU would decide to omit every 6th pulse to the coil, and leave the other 5 timed properly.
If it was an ECU issue, I would expect you would be in a "no start" condition.

Pull each plug wire until you find the dead cylinder.
Check that wire with a tester and see if it is firing effectively.

Last spring mine was running on 5, and it turned out to be a stuck injector.
I rapped on it with a socket extension while the car was running and it kicked in.
After that I was fine.

Amber Gramps

If you have a timing light just move it from plug wire to plug wife 'till it doesn't flash. That will tell you if you have spark or not, then its on to testing injectors if they all have a pulse......

Helios59

This is a real newbie question...and I apologize for thread-jacking...

...but how do you know you're not running on all six? Hesitation? Some special sound?

Thanks in advance, and sorry Dwight...I've wondered about this for awhile

irobertson

Rough uneven running, slow to spin up when revved, about a 25% loss in power.
It's really obvious when it happens.