cylinder misfire after gasket change

kpring · 11-16-2007, 06:21 PM

Had to change the 2001 Jimmy 4.3 intake manifold gasket due to coolant loss and 125m miles. Quite the job! Pretty damn sure every vacumn hose went back in the right spot and and wiring went back in the right spot. Changed the cap and rotor while everything was off, as well as the water pump. Started it back up and it ran rough. Took it for a tset ride hoping it would clear and it didn't. Service engine light came on.Took another look and saw the #1 plug that I took out to find out if the piston was at top dead center didn't have its wire put on and it significantly cleared up MOST of the roughness. Idiot light still was on, going from flashing to steady on a regular basis. Read the error code at Advance Auto Parts and it read #2 cylinder mis-firing. Bought a new plug, put the old cap and rotor back on, still running rough, and after carefully watching idiot light I;m noticing when you are slowing down to a stop, it stays on steady when RPM gets to 1000 and under, and upon accelleration and you approach 2000RPM, starts the flashing mode. I haven't tried changing the plug wire - yet, just didn't want to spring for a whole $$$et until I asked you guys for any possible other checks. Did replace the gasket with the bogus plastic and rubber gasket again, used RTV gasket stuff around the coolant ports and across the front and back "valleys" running it up about a 1/2 inch under the gaskets per the repair manual. At a loss now on what else to check. Any suggestions?

maxwedge · 11-16-2007, 06:50 PM

Focus on that cylinde,r the pcm sees the misfire, you feel it so something is happening, check cap, wire, plug, a full scan may be required to look at misfire counts, I assume the code was p0302?

MT-2500 · 11-16-2007, 06:54 PM

A flashing light is a miss fire.
You may also have to reset the dist camshaft retart on a good engine capable scanner.
Check and clear codes and see what code comes back.
Post back code no.

blazes9395 · 11-16-2007, 09:40 PM

Ha funny, I just got in from being inside the garage doing the same thing. I can't get mine to start....yet. This could be either an ignition problem or a fuel problem, specifically the #2 injector/poppit nozzle . When you removed the intake, did you do anything to the upper plastic plenum? Did you remove it?

I agree with MT on this, you for sure have a misfire (blinking light) you may (like me) need to reset distributor camshaft retard.
For sure get the codes scanned and post them here, and go from there.

kpring · 11-17-2007, 08:10 AM

code is P0302. I did not remove the upper portion of the intake, took off the entire unit as one piece. Guess I perhap should have. The ports were black but the nozzles were clear. Didn't want to screw around with those nozzles though.Was vey careful (so I think) blocking up the ports with small rags when I was cleaning off the old gasket material to make sure none of that stuff went into the ports or nozzles. I am going to reset the computer (unplug the battery for a couple minutes gonna do it ???), switch spark plug wires and then take another computer reading to see if the misfire changes to the cylinder I switched the wire to, just to make sure the #2 wire isn't bad. I'll let you guys know from there. Thanks for the help so far.

old_master · 11-17-2007, 08:36 AM

Quote:

Originally Posted by kpring

...I am going to reset the computer (unplug the battery for a couple minutes gonna do it ???)...

That will turn off the SES light but will NOT clear the codes. Gotta use a scan tool to clear codes from memory & reset the ECM.

kpring · 11-17-2007, 08:41 AM

code is P0302. More info on my repair. I did not remove the upper portion of the intake, took off the entire unit as one piece. Guess I perhap should have. The ports were black but the nozzles were clear. Didn't want to screw around with those nozzles though.Was vey careful (so I think) blocking up the ports with small rags when I was cleaning off the old gasket material to make sure none of that stuff went into the ports or nozzles. I am going to reset the computer (unplug the battery for a couple minutes gonna do it ???), switch spark plug wires and then take another computer reading to see if the misfire changes to the cylinder I switched the wire to, just to make sure the #2 wire isn't bad. I'll let you guys know from there. Thanks for the help so far. I'm reading some posts the reference resetting the distributor camshaft retard. How is that done and would that give a code?

maxwedge · 11-17-2007, 08:43 AM

Usually code p1345, this calibration must be done with a full function scanner.

kpring · 11-17-2007, 08:44 AM

Guess I won't unplug the battery. I'm reading stuff on resetting the distributor camshaft retard. How is that done, and would a bad retard show up on the computor with a code #?

kpring · 11-17-2007, 08:49 AM

So is it safe to say if I don't get that code, the retard is OK?

kpring · 11-17-2007, 10:15 AM

Went back to Advance Auto to read the computer after swopping plug wires and it still said the same thing, Cyinder 2 misfire and a pending code saying the same thing. I cleared the computer while I had the hand held device, but the SES came back on in less than an 1/8 of a mile. May have to bring this one into the pros to get it fixed. Don't want to go too long in this condition, heard that you can plug up the catalytic converter?

POST REPLY TO THIS THREAD