Possible ECM problem?

[JOHN07]

I have an 87' Riviera that is close to the Reatta. My problem is that I have an intermittent miss that I cannot find. I have recently rebuilt the motor and the miss is still there. I have checked or changed the crank sensor, cam sensor, ignition module and coil pack, new wires and plugs. I have also checked the egr valve by pushing up on it with the engine running and it will make the car stumble. I have had 2 mechanics look at it and they could not find it, but one thought it might be a balance problem. I do not believe this because it will sometimes run and idle without the miss. Has anyone else run into this kind of problem? Car has no codes in computer and no vacuum leaks.

Thanks JohnT

[2seater]

There was a guy on another forum that had a similar problem, primarily at low speed and idle, okay at higher rpm. He had recently done work on the car and discovered he had reversed two of the injector connectors, #3 and #5 I believe. His had numbers on them, although I have never checked mine to see if they are all like that? Long shot maybe.

[Guest DTerry]

I don't quite understand what "pushing up" on the egr valve means. If it has the same setup as the Reatta, try driving it with the egr valve disconnected so the ports remain closed.

[2seater]

I believe the '87 uses a vacuum operated EGR valve. The diaphragm is semi open on the lower side and it can be moved by hand. I suspect that is what was meant.

[ReattaBuckeye]

JohnT,

I had this problem with my 90 Reatta when I bought it a couple of years ago. My problem turned out to be the ignition module and coil pack (I had to buy 3 new modules to get a good one!). Had similar problem about 10 years ago with a 94 Buick Regal GS with 3800 V6 just after an oil change....problem was a pinched fuel injection electrical wire shorted to the fuel line under the "plastic" manifold cover! Kid mechanic at oil change center leaned over on the "manifold cover" while checking fluids and the wire was between the plastic clip and fuel line this pressure pinched the wire just enough to cause an intermittant miss....I got lucky finding it!