Continuing problem with 98 intrigue - misfire #6 cylinder

[rhettlucas]

Hi All,

I just joined the forum after doing extensive searches and becoming fairly frustrated at this point.

First a little history - 98 intrigue, 3.8l with 120k on it. My grandpa owned it from 30k to 110k. I bought it from my grandma after he passed away three years ago. So far I have put a new crank sensor in it last year, struts and swaybars this year.

Now the problem: Misfire #6 (I forget the exact code). A few months ago the car was running rough, put in new plug and misfire went away. Now it came back when my sister was driving the car. She drove it with the SES light flashing (16yr old stupidity). I pretty much new the intake gaskets were bad because it has been slowly using coolant for a while. Well, I pulled the UIM off and found alot of oil puddled up in the LIM. I changed both sets of gaskets and cleaned both manifolds in the parts washer thoroughly. Reinstalled everything and now still have the same bad miss at idle.

The first time I started it I noticed it wasn't right, so I pulled #6 plug which was wet again. So I cleaned it, stuck it back in and the same thing happened. I gave up at this point and ordered some new AC Delco wires and another new set of plugs. This past weekend I put these in and it didn't change anything. My father in law has a new Grand Prix which happens to have the same coilpacks (according to Rockauto searches) so I swapped those over too - no change. #6 plug is still wet even after 5 seconds or 30 seconds of running.

At this point I am kinda stumped - could it be the ignition module, cat plugged, fuel injector (haven't swapped those around yet)? At one point I did drive the car to see if it would clear up, but the car had absolutely no power and when I got turned around and back to the house, the U-bend pipe was glowing red. That leads me to believe I melted the cat, but I don't know how to do the backpressure test if it is.

Anyone have any ideas? I am 99% sure I didn't screw up the intake gasket installs and I looked over both fairly well and didn't notice any cracks or "issues" around the EGR that looked strange.

Any help would be much appreciated,
Rhett

[harmankardon35]

Injectors are your next thing to look into, also you didnt mention if you changed the plug wires, those things can go bad pretty quickly (i just replaced mine after about a year, same thing ironically cylinder 6 misfire)

generally anything to do with overall fuel delivery or plugged exhaust will result in a random/multiple misfire not a specific DTC