Random cylinder msifire!!!!!!

[Fast 95]

All back together, running good, BUT still throwing a random miss fire code, guess the coil is next.

 

[///RAGMC]

That was my guess from the start

 

[Fast 95]

We were using the scanner and watching the missfire hits, cyl 7 was the best, and cylinder 2 was the worst, it had some 123 counts, but they all had some. You cant notice a miss when driving it, sometimes when its idling you can feel it shuddering. Guess i know why my gas milage is so crappy

 

[///RAGMC]

I worked on a 98 Tahoe about a year ago that had 140000 miles on it and was doing the samething I was thinking the samething you were that the distributor was bad but I was starting with the basics before I put alot of labor into it just happen to have a coil in my tool box swapped it out and ran like a champ

 

[6chevy9]

i just started getting a missfire with my 97 vortec. i was wondering if i could get some opinions. it seems to do it off and on and just started after i put on the cowl hood. personally i think watter is getting onto the distributor or somthing to this affect. any ideas?

 

[Hodges87]

i just started getting a missfire with my 97 vortec. i was wondering if i could get some opinions. it seems to do it off and on and just started after i put on the cowl hood. personally i think watter is getting onto the distributor or somthing to this affect. any ideas?

I would check your cap and rotor first.

When is the last time you had a tune up?

 

[RSTahoe99]

Hey Fast95, do you have any logging capabilities? If so, look at your O2 sensors and make sure they are firing correctly. Mine starts to shutter and misfire when the O2 sensor acts up or goes bad. I bought the ****** Bosch sensors and will never do that again.

 

[Fast 95]

Pretty sure it has that option, i'll see if i can borrow it again, it was like to coolest tool ever. Wouldent that throw a sensor code and not a missfire code? I havent fooled with it since the last time, i'm thinking it may be more of an injector issue cause this thing eats the gas like crazy, but i'm still going to change out the coil. That will give me a compleatly new ignition set up.

 

[6chevy9]

it had a cap rotor plugs and wires this summer. which is why i dont think thats it. yesterday coming to work it was missing. coming home totally fine. today coming to work ran good again? beats me lol

 

[RSTahoe99]

Pretty sure it has that option, i'll see if i can borrow it again, it was like to coolest tool ever. Wouldent that throw a sensor code and not a missfire code? I havent fooled with it since the last time, i'm thinking it may be more of an injector issue cause this thing eats the gas like crazy, but i'm still going to change out the coil. That will give me a compleatly new ignition set up.

If you think about it the O2 sensors help the computer with the amount of fuel it needs. If the O2 is not operating correctly it will definitely throw your MPG way off. On the Pacific Performance forums we have discussed this several times, and have heard of poeple changing the stock O2 sensors over to Bosch on a completely stock motor and their MPG falling from 17 to 15 immediately. Then changing back to OEM sensors from the stealership and getting 17 MPG again.