Engine runs rough, like misfire

[buickmastermind]

okay, long story here.

I'm driving a 1991 Ciera with the 3300.

Over the winter, the car had been run off the road by a SUV and got stuck in a snowbank pretty bad. Snow all packed in around the engine...took it to a carwash and blasted it all away. This is among the last time I recall it actually running halfway right.

Some time before, the temp. guage started jumping around, going up with throttle, then when hitting bumps, randomly pegging itself.

After the snow stopped, the car very slowly began to develope a misfire feeling. over a peroid of 1 month, daily freeway driving, it loses performance, gas mileage. Though not really bad, (25mpg from 28), the computer began setting a code (44 I think), with pointed to the Ignition Control Module. Due to 140,000 miles on the car, replaced the module, the wires, plugs, and coils. Reset the computer, and worked perfect for two days. Even the temp guage starts working again.

Then, the misfire feeling starts up again, so I reset the computer, nothing. Take back all parts, exchange, and find that one fuel injector stopped firing. Replace it with one I know to be working, and made sure all injectors are firing. Everythings checks out. Put car back together. Still misfires. Checked all grounds, all plugs, sensors. Can't find an electronic issue.

Will check later today for loose wiring by the computer, and timing. I think I can hear spark knock, but not sure. All my tools are @ home, and I'm at school so can only work on it during weekends.


Has anybody at all had this problem before? Any ideas what I'm missing? Methinks I should get an old-school carbed engine...much easier to diagnose.

[JohnDD]

Code 44 is Oxygen Sensor Circuit (Lean Exhaust Indicated).

One of possible problems is "wire may be misplaced and contacting the exhaust manifold. Another is intermittent ground in wire between connector and sensor.

I had a 91 with the same engine but never had similar problem.

[buickmastermind]

Update: the center front cylinder is the one not firing.
It has spark
It has fuel
It has air

Closed gap on the plug to about .026, got a much brighter blue spark, and now get a sorta half-fire at high RPM (4000+).

I'm thinking compression, but it's is strange that only one cylinder would be doing this, at only 140,000 miles. Our other car has the same eng. at well over 210,000 and it isn't screwed up... I'll find some way to test the compression on that cylinder.

[buickmastermind]

Okay, it's been a little while, but problem solved. It was because the head had cracked, and blown apart the intake valve. Leaking valve = no compression. Figured I'd post in case anybody else had a problem like it.