2008 5.3 erratic miss

[harveje]

every now and then I feel a miss in the vehicle, just a slight shutter while idling. Put multiple scanners on it including a tech 2 and not even the slights sign of miss fire on any cylinders. Last week put new plugs and wires and yesterday rigged up a fuel injector canister but only found parts house cleaners to use so I used a combo of techron, berrymans, lucas, and a touch of seafoam, pulled the fuel pump fuse and commenced to flushing. Vehicle does run smoother but still has a miss or stumble (friggin annoying). I've ordered some OTC cleaner but does anyone have any suggestions, ideas, etc on what to check or do? All sensors look good and switching. Used propane around hoses and could not find a vac leak. vehicle has 100K on her

Thanks,

 

[TheFuzz]

There are lots of threads on this. The long and the short of it is: it's a GM thing. The newer 5.3's, for whatever reason, have very slight RPM variations at idle. My truck does it, and has since I bought it with 113k on the clock. I went through all of the same steps you have as far as trying to clean the injectors, seafoaming, etc. If you aren't getting any codes and it's not missing anywhere else in the RPM range, I'd chalk it up to the "GM chug" and let it be. I know that's probably not what you wanted to hear, but lots of us have the same thing going on. It doesn't hurt anything, it's just annoying.

 

[Goodinblack]

Some Fords are worse.

Ask me how I know. Lol

 

[harveje]

I understand but if i'd paid $1000 for it I'd live with it but OCD (I guess) is taking over.
My brother has an 07 with 160K and it idles extra smooth and I have an 2000 excursion with 210K 6.8L and it idles smooth. I'm sorry and I may have to live with it but I don't like it. I've read that there are allot of members with same issue, and seems to come and go. Some days it idles so good it's hard to tell it's running. I guess I can "borrow" parts off my brothers till I fix it... Anyway next is a good TB and MAF cleaning, then commercial fuel injector cleaner, then my mechanic has some 2010 injectors to swap in. Would an ECM reset or flash help anything?
Thanks,

 

[TheFuzz]

Doubt a PCM reflash will do anything. I'm tuned and my truck still does it. If you end up figuring out whats causing it be sure to let us know. Personally I'm not prepared to invest that much time and effort into solving an issue that doesn't bother me that much...but if you are, I will live vicariously through you for a bit.

 

[Leedogg]

My 07 AV does the same thing- my 01 Burb does not. It is a lil annoying. I wondered if it had to do with the AFM on the Avalanche...

 

[harveje]

I guess some things bother me more than others ex: wife asking why her newer truck shakes sometimes and not others, me- honey some vehicles do and some don't- wife- but why, so n so's don't shake, your an engineer fix it...So here I am.. But if I do find anything I'll post...Thanks for the help

 

[992dr]

My 07 Tahoe did this to. I swapped plugs and wires and it seems to have calmed it down quite a bit.