Im having trouble with my 91 Firbird (305 TPI). To give you a quick summary of the car..... Had it for a couple years now and it hasnt seen the road much (its a project car). For the most part the engine has always run strong. Had a problem with the motor not "reving" past 4000 RPM's but a new coil/module and pickup solved that problem. Anyway..I hadnt started the car in a while so I decided to pull the coil wire off the cap and crack the car to build oil pressure but I forgot to pull the fuel pump fuse ). Ok so that wasnt one of my "brighter" moments in life... Anyway.. I put the coil wire back on and the car runs perfect..no missing no rough idle.. I notice as the car is warming up its starting to run rougher and rougher.... I rev it up...the idle smooths out.. So I decide to take it for a ride.. the car missing like crazy (very noticable smell of gas outta the pipe)..its bogging (step on to the gas pedal and it just "farts and dies." At first I thought maybe I fowled the plugs out (doesnt seem possible due to the fact it ran good for about 10 min.) I ended up replacing the 4 "easy" plugs and it runs a little better <~~~*wishfull thinking* but the problem is still there. (the 4 plugs that I pulled didnt look or smell like they were gas fouled) Dont have a fuel pressure gauge handy but the last time I checked it fuel pressure was "good." I doubt its fuel related... No check engine light and I didnt get any codes from the ECM. Took the distribtor cap off hoping to find something burnt up...nope...rotor and distribtor cap look good... As far as I can tell the spark plug wires dont look like they got burned up by the exhaust manifolds.... Would be nice if I had a snap on scanner handy. lol All i have is some POS GM expertec scanner...(not that great) What do you guys think?

Dan

 

Sounds like maybe an 02 sensor, or in my case it was the injectors were shot. My car would run perfect till it warmed up, then the injectors were hanging open, making the car VERY rich, but not to the point of fouling up the plugs. You could smell it in the oil though. Check the resistance on the injectors at their connectors. SHould be between 14-17 ohms I believe. I changed the injectors and 02 sensor.....works fine now....Good luck.


FWIW, I didnt have a problem with my injectors till I let the car sit for about 6mths....something to think about.

 

Ever since this problem developed I felt it was ignition related...(gut feeling). I took the ignition coil off and module and went to auto zone to test them...the module passed but they didnt have a meter to check the coil (i didnt have a meter either)... Took the coil to a friend with a meter and the coil checked out ok as well.. AT this point Im just running out of ideas....The problem was right in front of my face...Theres a 2 wire connector that runs from the module to the coil (Im assuming that this connector supplies "juice" to the coil) Anyway..someone had pierced the insulation of this two wire connector and over time the insulation had "bubbled up" and it wasnt making a good connection what so ever.... So as a temp fix at 11 PM at night I made up a small two wire connector with male butt connectors on one side (for the coil) and I "borrowed' a gm connector from another wiring harness I had lieing around... At 11:15 PM I started it and it sounded great! Had to shut it down real fast because I didnt want the neighbors to get pissed.... Just started it up now and it runs pretty good...sputters a little but Im pretty confident that its from the "gehto" wiring harness I made.... Once I get the right harness Im pretty confident its run perfect...

Later..

Dan

 

I was wrong...Its STILL not fixed.. I still think the wiring was part of the problem but it still does the same thing.....(bogs..backfires here and there). Maybe I made more problems.....I really dont know. It runs pretty damn well at idle (has a slight miss I think but nothing major) but as soon as I put the car in first and let the clutch out it runs rough and dies.. If I give it gas and Im in first I can get to second gear but it runs very rough..holds back ect ect) Im without a scanner (right now) and Im running outta ideas. Ive got just "STUPID shot in the dark" guesses like I gapped 4 plugs at 35 thousandths and the other side gapped 40(?) thousandths and thats the problem (doubt it) Maybe the coolant temp sensor is reading WAY outta range... Maybe the one sparkplug wire I ripped (accidently) and then taped up is causing the problem (I ripped the insulation on it and taped it up with electrical tape...not the greatest fix I know) I dont know....

Later..

Dan

 

I think I quite possibly did the dumbest thing ever in automotive field... I ended up talking to an old "automotive mentor" today and he told me that most likely I "killed" the coil by pulling the coil wire off while cranking it.. I started to think about it and I remembered that when I did that I heard "spark" but only for about HALF of my "inital crack time".... Long story short I put a stock coil in and that fixed the problem..

STILL have more questions though...

It is "ok" to run a stock coil with a performance module?

Took the car out for a run and it runs like it used to BEFORE I killed the coil. Came back to my driveway only to find cat fragments. NO not an actual cat but pieces from my catalyic converters (i have 2). Now Im not 100% sure that these pieces came from my car but I cant picture any other car that it coulda come from. I have 3 inch exhaust so Im sure that pieces of that cat could have been blown outta the tail pipes. Id say that all in all I might have put 4 miles on the car running the way it was (prior to fixing the problem).... I cant picture BRAND NEW CATCO CATS breaking apart after 4 miles of running like crap. (Note: I put on a total of 1000 miles on the car itself WITH these cats/3 inch exhaust). What do you guys think? Maybe tomarrow I'll crawl under the car and punch the cats with my hand to see if they sound like they're brittle.....

Dan

 

which wire did you pul off of the coil... mine is running like crap too (after it warms up), and one of my coil wires was broken, i repaired it, but it still runs crappy.