Starting To See A Stumbe Or Miss At Cruise

c4cruiser · April 5, 2010

Lately I have noticed a slight stumble or miss when cruising at speeds of 45 and above. It's more noticeable on the freeway at 55-60 and under a slight load like slight inclines of 1-3%. On cold starts in the AM, I also feel a definite miss at idle for the first 30 seconds or so. No CEL.

The engine is the 6.0L and I currently have just over 13,500 miles on it. It's my DD and I do some towing but only 6-8 times a year for relatively short distances of <100 miles.

Is this typical with 6.0L AFM motors? Lifter or valvetrain problem?? I haven't been to the dealer to discuss this as yet, so I would really like to get some suggestions as to what sort of questions to ask or how to better describe the issue. My dealer is great to work with (they sponsor our Corvette club) and the service writers are helpful.

jdg2 · April 5, 2010

Lately I have noticed a slight stumble or miss when cruising at speeds of 45 and above. It's more noticeable on the freeway at 55-60 and under a slight load like slight inclines of 1-3%. On cold starts in the AM, I also feel a definite miss at idle for the first 30 seconds or so. No CEL.

The engine is the 6.0L and I currently have just over 13,500 miles on it. It's my DD and I do some towing but only 6-8 times a year for relatively short distances of <100 miles.

Is this typical with 6.0L AFM motors? Lifter or valvetrain problem?? I haven't been to the dealer to discuss this as yet, so I would really like to get some suggestions as to what sort of questions to ask or how to better describe the issue. My dealer is great to work with (they sponsor our Corvette club) and the service writers are helpful.

I have had the same issue with my vmax since day 1. I have had Justin at Black Bear Performance try and figure it out while doing a live tune and it just won't go away. Seems a little less noticeable since I went from 87 to 89 octane and also turned off AFM, but it is still there. I think some do it and some don't. Hope you find an answer for all of us. I had posted about this a while back.