Occaisionally, seems to be missing on one cylinder...

[Rickkins]

1995 trans sport/ 3.8 engine
It'll be going along fine, then all of a sudden, sometimes, it starts running really rough, like it's missing one cylinder, or something.

Changed the wires, cap, rotor...gonna change the plugs this aft.

Thoughts...??

Thanks

[rkvons]

Originally Posted by Rickkins

1995 trans sport/ 3.8 engine
It'll be going along fine, then all of a sudden, sometimes, it starts running really rough, like it's missing one cylinder, or something.

Changed the wires, cap, rotor...gonna change the plugs this aft.

Thoughts...??

Thanks

Chevron Techron Fuel system cleaner.

[LMP]

Like rkvons implies, a failed injector is a possibility. However, with sudden total misses, a cleaning job has little chances of success. If it fails enough at one time to roughen the idle, then disconnect injectors one at a time...the one that does not make a change is the culprit. Of course....hope it is one of the front three.....There has been at least one case on this forum where the driver transistor for one injector was the problem, not the injector itself. I think the transistor was a discrete component and could be changed .
EDIT: Yeah: found here : http://www.automotiveforums.com/vbul...d.php?t=507692
HOwever, as simple things are best to begin with, tell of the result with the new spark plugs....mmm.if need a trick for the rear ones.....I can suggest....http://www.automotiveforums.com/vbul...d.php?t=599442

[Headnsouth]

If you go to a auto parts store they can scan for codes and MAY be able to tell u which cylinder is misfiring. It'll help narrow down the problem. Could be a bad coil. If the plugs haven't been changed in 100k u should, the back three are a PITA. But best done from underneath. IMHO

[rkvons]

Originally Posted by Headnsouth

If you go to a auto parts store they can scan for codes and MAY be able to tell u which cylinder is misfiring. It'll help narrow down the problem. Could be a bad coil. If the plugs haven't been changed in 100k u should, the back three are a PITA. But best done from underneath. IMHO

Is it hard to start every now and then? I had those symptoms and it turned out to be dirty injectors. I agree with changing plugs from underneath.