crazy missfire issue, has two mechanics stumped!

[ssms5411]

Re: crazy missfire issue, has two mechanics stumped!

My guess is a bad injector out of the 6 , just enough for the misfire and to run bad. You could OHM check them , should be between 14-19 ohms. But they could still be clogged even if they check out with a OHM meter. Only way I found mine was they put the bad injector in the #1 cyl. and the car wouldn't start. So I would at least ohm check the injectors.

[Beefcake]

Re: crazy missfire issue, has two mechanics stumped!

I've never seen an injector fail before but I guess that could be an option. I'm hoping its the fuel filter but i'm hoping to find out why the knock sensor and crank sensor codes are always there.

[ssms5411]

Re: crazy missfire issue, has two mechanics stumped!

Mine failed at 120,000 miles. It was only 1 and the others were fine.

[97RSRPV]

Re: crazy missfire issue, has two mechanics stumped!

sounds like my MAF sensor problem... generally faulty MAF will throw a code.. sounds stupid but run the car and tap on it see if it straightens it self out for a lil bit. if it does you know its the MAF. I believe its called a Tech 2? Correct me if im wrong but i belive that is the general GM dignositc tool.

[mrhobbz]

Re: crazy missfire issue, has two mechanics stumped!

sounds like my MAF sensor problem... generally faulty MAF will throw a code.. sounds stupid but run the car and tap on it see if it straightens it self out for a lil bit. if it does you know its the MAF. I believe its called a Tech 2? Correct me if im wrong but i belive that is the general GM dignositc tool.

Or just unplug the maf and see if it runs better.

[Leonard 3.8L]

Re: crazy missfire issue, has two mechanics stumped!

I remember having MAF problems in the past. It took longer to figure out what it was because they don't always throw codes.

[mrhobbz]

Re: crazy missfire issue, has two mechanics stumped!

I had the same identical issue, plugs were fine, fuel pressure/pump was fine, unplugged my maf and ran it for a little while and the issue went away. A new maf sensor ended up resolving the problem.

[Beefcake]

Re: crazy missfire issue, has two mechanics stumped!

Unplugged my MAF sensor and drove it to the store and it ran identical. Didn't want to crank the first time of the day like normal. One thing I did notice when I gave it a full throttle run is that it ran fine through 1st and 2nd but when I got to third it started backfiring uncontrollably until I shifted into 4th. I let the motor get to operating temps before I did the full throttle.

[RadRacer]

Re: crazy missfire issue, has two mechanics stumped!

well, that rules out MAF for the most part.....any more updates on those fuses?

[Beefcake]

Re: crazy missfire issue, has two mechanics stumped!

All fuses under the hood checked out, There were a few fuses that were bigger and gray, but I dont know how to check those. I think I'm gonna buy a fuel filter and change it just to see what happens. If that doesn't fix it I guess I'll try an Ignition Control Module and a fuel injector. If it still is not fixed after all that I'm definetly gonna sell the car and get an 03' Monte Carlo SS. I'm just tired of the all work that has to be done to this car to keep it on the road...the money I spend in parts every month is the equivalent of a car payment anyways...

[mrhobbz]

Re: crazy missfire issue, has two mechanics stumped!

All fuses under the hood checked out, There were a few fuses that were bigger and gray, but I dont know how to check those. I think I'm gonna buy a fuel filter and change it just to see what happens. If that doesn't fix it I guess I'll try an Ignition Control Module and a fuel injector. If it still is not fixed after all that I'm definetly gonna sell the car and get an 03' Monte Carlo SS. I'm just tired of the all work that has to be done to this car to keep it on the road...the money I spend in parts every month is the equivalent of a car payment anyways...

Just out of curiosity why an 03?

[Beefcake]

Re: crazy missfire issue, has two mechanics stumped!

Because I seen one for sale in my price range at a dealer near my house

[Beefcake]

Re: crazy missfire issue, has two mechanics stumped!

Fuel filter and crank sensor did not fix it... you guys got any advice on how to test injectors to see if they are working?

[Archer]

Re: crazy missfire issue, has two mechanics stumped!

injects dont seem to be the culprit. If they fire fine 1-2-4 and it only stumbles on 3, I can not imagine them being bad. as far as testing them, your manual should explain how to check voltage, as far as if they have the right flow, you'll need to have a shop do it with the correct tools to see if they have the right PSI... that is really weird that it drives fine in certain gears, but 3rd gear just kills it. ever think about taking it to the dealer, explaining to them what you have replaced and have checked. They may have run into this situation before. Just my .02

Luck
Archer

[ssms5411]

Re: crazy missfire issue, has two mechanics stumped!

I had a bad injector that would give me misfires, the only way we found it was we put it the #1 cly. and the car wouldn't crank , so got a new one and started up fine. Ohm tested it and it all checked out , just went bad either something internal with it, had 122,000 miles on it so it had some miles. I had that misfire for about a year replacing this and that if it wasn't for doing my rebuild and the mechanic putting it in the #1 cyl. I would of still had a misfire after the rebuild. I would sit at the bank drive through for about 15 minutes and then take off and stop for the turn and it would die sometimes and sometimes just throw the misfire code. That was the worst problem I didn't know how to fix since I have owned my car for 13 years.