Buying 2007 Yukon 5.3

[bills02yukon]

My wife has a 2005 GMC Yukon SLE 2WD 4.8 V8 with 143k miles and I am looking to replace it with a 2007 GMC Yukon SLT 4X4 5.3 V8 with 148K miles and active fuel management. How common are the problems with the AFM system?

Thanks

 

[NathanJax]

They aren't too common. Never had an issue with mine. You can always have it turned off via a tune. It's kinda a hit and miss thing. Some people have had issues, others haven't

 

[bills02yukon]

Ended up buying it for $10,500. It's in really good shape and has all the bells and whistles like heated leather seats, power folding rear seats, sunroof, video system etc. The only things I have noticed with it is a slight clunk when turning slowly in parking lot. There is no play in the steering wheel and it drives straight. The other issue was when I test drove it the idle was at 500rpm and would fluctuate a little lower with a rough idle. I put in a bottle of Tecron and removed and cleaned the throttle body and MAF sensor. The throttle body was caked with black residue. Now it idles around 550-600 and smoother but still isn't as smooth as the old 2005 4.8 V8

 

[NGAneer]

That's just the way these idle. I had the same concerns from the 99 5.3 Silvy to my 07 5.3 Yukon. I've changed plugs, run every fuel system cleaner you can think of, added PCV filtration. It still just has a little bit of a weird idle compared to non-AFM engines. Just clean the air and fuel systems the best you can (within reason) and let it be. For the most part these engines are bullet proof in my opinion.

 

[Plimbob]

Ended up buying it for $10,500. It's in really good shape and has all the bells and whistles like heated leather seats, power folding rear seats, sunroof, video system etc. The only things I have noticed with it is a slight clunk when turning slowly in parking lot. There is no play in the steering wheel and it drives straight. The other issue was when I test drove it the idle was at 500rpm and would fluctuate a little lower with a rough idle. I put in a bottle of Tecron and removed and cleaned the throttle body and MAF sensor. The throttle body was caked with black residue. Now it idles around 550-600 and smoother but still isn't as smooth as the old 2005 4.8 V8

I was having issues with my 07 Tahoe 5.3L (AFM) idling rough at about 165,000 and it turned out that cylinders #1 & #7 the plugs were fouled. I had read on the forum that because of the AFM sometimes those cylinders will foul. I now change them out about every 20k and it idles just fine? I now have 220,000 on it.

 

[bills02yukon]

I checked the plugs that were in it and it had just plain old Autolite's. I replaced them with AC Delco Iridium plugs and new AC Delco wires. After a few times of hard acceleration it seems to be idling a little better

 

[Plimbob]

I checked the plugs that were in it and it had just plain old Autolite's. I replaced them with AC Delco Iridium plugs and new AC Delco wires. After a few times of hard acceleration it seems to be idling a little better

Bill, excellent point. I forgot in my thread to mention that I had Autolite plugs in mine they easily fouled so I replaced with AC Delco. Also, over the course of time I did also have an injector go bad which was causing some rough idle one time. May want to check those.

 

[08HoeCD]

Regarding the 'clunk' at low speeds, check your sway bar links and bushings.

 

[bills02yukon]

The rough idle/vibration seems to be worse at idle with it in gear. While in park it's hardly noticeable. Would that be consistent with a motor mount?

 

[NGAneer]

Regarding the 'clunk' at low speeds, check your sway bar links and bushings.

Yep. Had to replace mine again this weekend.