This actually doesn't pertain to LSX, just GM fuel injected in general, but I needed a few more viewpoints.

I've developed an idle / low rpm random misfire with no OBDII codes and can't seem to track it down. I found and repaired a vacuum leak, changed fuel filters, plugs, and wires. The fuel pump is less than 6 months old. It varies in intensity (I let it idle for about half an hour and sometimes it was worse than others) although it seems to be a little worse when the weather is cold.

What has me confused is that the hesitation and lack of power (not to mention fuel economy heading sharply south) is fairly constant but, I just noticed that if I floor it, it's sluggish up until about 4500 RPM or so (don't have a tach so I'm guessing) at which point I get a noticeable surge and all the power back.

Any guesses as to what I can look into next?

 

Is this a question about an F-Body? If so, what specific engine are you asking about? The "tech" forums are for F-Body questions only. Please clarify.

 

I did.


Sorry to waste your time. Never mind.

 

usually its the freaken opti-spark. or maybe the coil. i had a 94z a4 and it was a optispark issue. i forgot your year but 93 through 95 have non-vented opti's. they cant breath. so they have more build up inside and dont release the humid stuff from all the heat. my car was a 383 stroker but had about 180k. punks rolled back odometer. it was farting alot or misfiring. ended up being the opti. whenever you do the plugs and wire it is wise to also do opti and waterpump.espeacialy water pump cause it will leak onto you new opti. causing a love hate relationship. got rid of my 94 shark

 

Thanks for the response. It's actually an 01 2.2L...I know, wrong place, but I was running out of ideas and figured someone might be able to throw something out there since the general principles are the same. I was really just looking for general troubleshooting ideas. I've eliminated the entire electrical end now, so I'm thinking dirty / sticking injectors or compression...possibly one of the sensors. I'm going after the injectors next.

If I didn't need this thing for work, I'd be rid of it already.

 

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