98 4.3 4wd Blazer engine running rough
 

So I have I a 1998 Blazer 4.3L 4door 4wd, its got about 134k on it and so I decided to chang the spark plugs and wires last weekend. I replaced them with AcDelco Platinum plugs as recommended by others on the forum and got a champion wire set. All the plugs were gapped properly to .60 inches and all of them went in fine. Except number 3, it was a real pain to get out and I know I stripped the old plug getting it out and could not see any damage to the threads inside. When I put the new one in, it seemed to go all the way in (went as far as I could tighten it). But now the engine seems to be running/missing on a cyclinder.

I was wondering if the plugnot being in all the way would affect the running of the engine, if that was the incorrect gapping (I looked in the Haynes Manual for the info), is there a recalibration time for the computer control module or what might possibly be wrong. Any thoughts or possibilites would be greatly appreciated.

-Lenny

RE: 98 4.3 4wd Blazer engine running rough
 

Yes it will, because the plugs are designed to be seated at a specific distance. If the plug is not properly seated then when the plug ignites the fuel in the cylinder it will travel differently, and causing the computer to record a misfire.

RE: 98 4.3 4wd Blazer engine running rough
 

Also, if the plug is not seated into the taper, you'll have a compression leak on that cylinder. You should be able to hear this as a slight ticking sound near the plug.

RE: 98 4.3 4wd Blazer engine running rough
 

thanks for the help guys, it seemes to be running better, just put about 500 miles on it since I had to run home unexpectenly, still got 22-25 mpgs on the highway. only seems to be sluggish around 25 mph or after kicking off the cruise control. I was wondering if the plug was not seated proplerly would this cause fatigue on any of the components or create build up of like carbon or something? This is plug #3 so it would be a pain to take back out again, maybe ill take it to a shop to do it cause i dont really want to mess with it.

thanks again for the help.

-Lenny

RE: 98 4.3 4wd Blazer engine running rough
 

Is it still running rough??? It is also possible that a plug wire may have worked loose...I have read on the forum that the crab cap distributor cap can "push" the wire boot backwards enough to cause a rough idle, did you use dialectric grease on the wires. This condition is usually caused by small air pressure build up when pushing the boot onto the cap, to eliminate this some people will use a small pocket screwdriver or wire to eliminate the pressure build up when sliding the boots onto the cap.

Also did you replace cap/rotor??? at the same time...it is possible that the inside of the cap may have a carbon build up causing arcing inside the cap.

It is also possible that the wire set you bought is defective, quality control can't always catch every bad set...