Randy Farrell

Hello everybody 1983 s automatic runs great until it gets to 3800 rpms and then starts missing and cutting out. I have been trying to figure this out for awhile with no luck. There are times when the car is started but not quite warmed up all the way it will go right up and go like a raped ape all the way to redline but I stop short of that. Then its back to the same issue at 3800 falls on its face again. Any ideas would be great.

The Forgotten On

Common issue. The Distributor is 1 tooth off (advanced) so you need to pull it and reinstall it 1 tooth retarded from where it currently is.

Then set the timing to factory spec using a timing gun.

Not a big issue to deal with fortunately.

Randy Farrell

that makes sense I thought I had it right I Will check it tomorrow. Thanks Blake.

copperstew

My advice is to go through the diagnostics in chapter 28, page 11 of the workshop manual.

There are extra troubleshooting advice in the 928 L-Jet Manual.

Not in the manual, but possibly relevant...get some readings on a wide-band air-fuel meter. If the mix goes rich when it stumbles or if it is running rich all the time, it might point to other causes like a failing L-Jet ECU/DME. When you are over a certain percentage of throttle the throttle lever will trip the WOT reed switch on the throttle body and send a signal to the ECU to dump extra fuel into the intake. Normally this has a desired cooling effect in the catalytic converter, but if your ECU is faulty and running rich already then it goes overboard and drowns your engine. Your cat can also get extra hot as it tries to deal with all the unburned fuel.

There is no easy test for a failing ECU other than to swap in a known good one (which is super easy to do if you have a spare ECU).