Random cylinder msifire!!!!!!

[Fast 95]

I just dont know, one time it runs fine, and the next like a dog. If it was mechanical, wouldent it do it all the time?

 

[RSTahoe99]

no not necessarily, especially if it is a small crack in the head gasket. EX. if its a small crack the gasket will shrink in colder weather, leaking water into the cylinder, corroding things causing misfires. After the motor heats up the gasket expands and closes the gap wher it is leaking and viola the truck stops misfiring and runs fine, giving the illusion that it comes and goes.

 

[Fast 95]

Sometime it runs fine when cold and like $hit when it warms up. I pulled the distrubitor today to check the gear to see if it was worn, but it looked good, got it all back together and started but i'm waiting on a friend to bring over a scanner so i can set the cam retard and make sure the timing is right. I really dont want to pull the heads off, its 4wd and sits so high, i have to stand on a milk crate just to work on it now. That and i hate torquing head bolts with the engine in the truck, hard on the back if you know what i mean!

 

[noremac]

hard on the back if you know what i mean!

thats what she said....


but in all seriousness, (my mind is failing me at the moment) does the computer adjust the timing somewhat when running on a tbi? i dont think if your timing was set at a specific amount, then it would act the same no matter what....

 

[Fast 95]

Its not a tbi motor, its a vortec, cam retard has to be set + - 2 degrees from 0 at 1000 rpm.

 

[6chevy9]

man i still cant belive we havnt figured this out yet. wouldnt a cracked head have the same cooling and warming effect as mentioned above?

 

[noremac]

i would say so... i just cant believe the timing being the issue...

 

[Fast 95]

I dont think the timing is the issue, i had the distributor out today, thats why it needs reset, lol.

 

[Fast 95]

man i still cant belive we havnt figured this out yet. wouldnt a cracked head have the same cooling and warming effect as mentioned above?

But im not losing coolant, its not smoking, oil is clean. I'm tired of fooling with it, but want to get it fixed. I'm going to drive it tomorow with the Tech 2 hooked up to see if anything jumps out as being wrong.

 

[6chevy9]

yeah thats true too. are you 100% sure nothing is getting the dist wet? oh wait, did you do anything with the ignition conrol modual? the tech 2 sounds like a great idea. my vortec misfired randomly also due to a icm but the lower compression in one cyl still gets to me.