3.1 running VERY rough

[brenthye]

little long. I've recently been having problems with it ('91 beretta) running rough where it would be normal then it sounded like one cylinder wouldn't fire all the sudden, then after a random amount of time it would stop, also, turning it off and back on would cure the problem. I thought maybe plugs/wires, so I replaced them with a cheap set (yeah, yeah, I know) and after doing that it has been many times worse. now it will no longer run normally, and instead there is a constant lack of power like one or two cylinders aren't firing, the thing is absolutely flacid in acceleration, but is extremely loud. it also back-fires with anything more than ~5% throttle. though I did try, I'm not 100% sure the wires were put back properly. I got from another post that the firing order is 1-2-3-4-5-6 and the coil order is 1-4-3-6-2-5. Is this correct? and is the front passenger cyl #1? TIA! -Brent

[Jon89LE]

Seems like you have it right. In the front its 1-3-5 and back is 2-4-6. My 3.1 had a problem similar to that back when my Dad had it and it was the Coils. Back firing, blowing smoke, ran on like 4cylinders and the tranny started shifting funny. If you can get that problem to occur at idle, disconnect the wires one at a time and ground the inside of the wire with a screwdriver to somewhere on the car. Chances are that if its a bad coil, the plugs that you remove wont effect the roughness of the car and wont spark when you ground it.

[TrailMug]

Did the engine just turn off outright after running at any rpm? Low fuel injector resistance can cause the ECM to turn off the fuel injector drive circuit to keep from overloading it. Low injector resistance can be caused by shorted injector coil turns.. Take a multimeter to the inejctors with engine cold, they should read around 12.6ohms if I remember correctly, and should be within roughly 10% of each other.

[TrailMug]

Actually, now that i re-read, recheck that wiring. The front bank of cylinders (radiator side) is 2-4-6. Cyl 1 is the passenger rear. The manual specifies 14 63 25 for the coil connections, but i would think getting them attached to the right coils should be ok.