high load / low rpm misfire

[tommyturbo]

1995 MTX
Noticed this today, that under higher load the engine misfires around 2500 to 3ooo rpm. It can be subtle or more noticeable. Think cruising at 2500 in 5th, and open throttle, it will miss a few times and then pick up. Also under high load in 2nd it missed a few times also. Seems perfectly happy and doesn't miss any other rpm ranges. Runs to redline just fine. Ran codes, just 111.

I've had this car a long time, did plugs / wires in 2007ish at 105K when I got it, now has just shy of 150K. I'm leaning towards plugs / wires, just would like confirmation I am going in right direction as I had a weird super subtle miss on my 95 ATX around 3K underload that turned out to be the cam sensor.

 

[Irish Pride]

12 years is a long time for SHO plug wires. The plastic boots get dry and crack. I'd venture to say if you pull them off they might fall apart in your hands.

 

[luigisho]

I agree. Also look for oil in the spark plug tubes.

 

[tommyturbo]

I thought about the oil as well.

 

[BaySHO Performance]

I've seen many cars with plugs immersed in oil, and the car runs fine. Often when I have this problem (car fine under gentle acceleration, bogs down under load) it has usually been dirty MAF filaments or a vacuum leak. Spraying starter fluid over likely leak points may show up something.

 

[tommyturbo]

I suspect the car has a very small vacuum leak some place as on long hills the ac will switch modes, been this way for a long time....Years. Have never found the leak. Never had any lean codes, or misfires until recently. I plan on cleaning the mass air when I do the tune up this weekend.

 

[tommyturbo]

Plugs and wires done. Rear bank boots came apart on me, front not as bad. No oil in plug wells, but looks like some moisture got in in the past. Plugs had some oil on them, but other wise look normal and worn. Gonna take a shower and drive it. Idle is nice and smooth. Need to get a new can of mass air cleaner.

Drove the car,runs great and feels strong!