2004 GMC Yukon flex fuel edition issues

[OR VietVet]

Please tell me you did the knock sensors and harness while in there......

After looking at the video after I posted what I did, I see the old ones removed form their homes. Great.

Plus, I am really glad that the MPG came back and runs fine. Keep posting for a little bit with mpg and driveability updates. Good job and have to be happier for sure.

 

[bmpalevich]

Oh yes I did change them even though I was in there in 2019 and changed them then better safe than sorry! I will post about it every other day or so it did have a lil hiccup when warm it started weird? Kinda like a clunk

 

[bmpalevich]

The fuel mileage is definitely way better I am pleased about that but the start up when hot is kinda odd didn't have this before it clunks it cranks maybe 2x then clunk then it's running perfectly. Shut it off wait a minute then it starts normally if I leave it for 10 minutes or more it does it again.

 

[Mudsport96]

The fuel mileage is definitely way better I am pleased about that but the start up when hot is kinda odd didn't have this before it clunks it cranks maybe 2x then clunk then it's running perfectly. Shut it off wait a minute then it starts normally if I leave it for 10 minutes or more it does it again.

Clunks and cranks? Only thing that should make any type of noise would be the stater...

 

[bmpalevich]

Yes start the engine and it starts oddly it's not the starter lol its definitely engine trouble

 

[OR VietVet]

Compression test time.

 

[TollKeeper]

I was thinking more along leaky injectors. The clunks has me worried that its trying to compress liquid.