Electrical Problem II

[nightone666]

1993 grand prix se 3.4 v6 177,000mi
hi all help if you can about 3 weeks ago car started running rough would not idle rpm's would drop off like car was shutting off car has (tack) while running @speed 55/ 2200 neddle would dive to 0 them bounce back to running i tested everything electrical that i could then i gave up i took car to a mechanic very trusted one (asc cert) and shop teck's
he replaced in this order crank sensor, control module and last but not least control computer he spent over 20 hrs checking and looking for shorts broken wires ect and nothing ( car now has it's moments some time runs like a champ then back to problem above) when you stump the mech you have stumped every one any help or ideas would be welcomed tks

[fantastic]

What about things like the fuel filter or distributer parts? I have an 02 GT that sometimes had a rough idle. It would run well down the road and every so often have a sputer that caused my rpms to drop.When I looked into it the fuel filter hadn't been changed in 2 years. Once I changed it the shutter went away and no more issues. I'm not an advaced tech of cars so I could be out in left field with this post but every little bit helps.

[richtazz]

I agree that a fuel pressure test should be performed. How long has it been since this car has been tuned up? GM DIS ignition systems will sometimes randomly shut down when subjected to high secondary resistance caused by worn plugs, bad wires, etc...

Finally, never eliminate a part just because it was replaced. The ECM's in these cars are mounted under the hood, and are exposed to the elements. This leads to a higher than normal failure rate. Did you put a new/reman ECM in, or a salvage part? If the replacement ECM was a reman unit from Cardone, it could very well be your issue still, as they are of questionable quality.

[nightone666]

thanks for the quick reply fuel pressure is 48 lb's @ the rail
new filter was instaled new plugs and wire set over 1 month ago coil packs tested and passed as far as the ECM not sure told it was new thanks Ray