Sluggish? 4.4 feels like 4 cylinder...FIXED!!

[sethhatfield]

Alright. Swapped #8 and #5 spark plugs and still got a P1357 which is a #8 misfire. No other codes! Aaarrgghh!

When you floor it, it won't shift into 3rd gear because it won't rev up past 4000 rpm. If you let off the throttle a little, it shifts normally. Not a transmission problem just the engine isn't revving up under a load.

[sethhatfield]

I think the consistent #8 misfire is just a symptom of another problem obviously. I'm leaning toward cats. I'll gut those things in a heartbeat and find some gadgets to fool the aft O2 sensors if need be.

[upallnight]

Originally Posted by sethhatfield

Alright. Swapped #8 and #5 spark plugs and still got a P1357 which is a #8 misfire. No other codes! Aaarrgghh!

When you floor it, it won't shift into 3rd gear because it won't rev up past 4000 rpm. If you let off the throttle a little, it shifts normally. Not a transmission problem just the engine isn't revving up under a load.

Misfire could be due to bad coil, spark plug, injector, or low compression. Since you swapped the plug and the misfire is still in the same cylinder I would

1. Do a compression test of Cylinder 8
2. Swap the coil with another cylinder and see if the misfire doesn't travel with the coil.
3. see if the injector is working in cylinder 8. You can use a stethoscope to listen to the injector to see if it is clicking.

Engine won't rev under load, sounds like you got plug cats.

[sethhatfield]

I believe if it were an injector, it would rev up past 4000rpm

[sethhatfield]

Having the cats changed for $350 right now!

[sethhatfield]

I'd like to thank everyone for their help!

It was the catalytic converters. I had a couple of universal cats installed and the old ones were broken up internally. It runs excellent now.

[upallnight]

Can you edit the title in the original post to say FIXED so that other owners with a similar problem can find a solution.

[J.Belknap]

Good to hear!