What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[Doubeleive]

@Doubeleive So your fuel pressure is running at 55 psi? Is that commanded as well? Either way, I've never seen with any of mine, they always run 43.5 psi at idle and at WOT.

What is your Fuel Pump's LT Trim? I believe this is way to gauge the pump's health.

it only did that one time, I'll have to go out and see what lt trim is I think it is fine though the pump is only 1yr old had it replaced by the dealer last year

 

[Doubeleive]

@Doubeleive So your fuel pressure is running at 55 psi? Is that commanded as well? Either way, I've never seen with any of mine, they always run 43.5 psi at idle and at WOT.

What is your Fuel Pump's LT Trim? I believe this is way to gauge the pump's health.

 

[Doubeleive]

averages from a 9 minute run, I'll try and video the playback or if anyone has any idea how to decipher a efi file I can send it via google drive or something

 

[j91z28d1]

averages from a 9 minute run, I'll try and video the playback or if anyone has any idea how to decipher a efi file I can send it via google drive or something
View attachment 434939

not that I think it's the fuel pump, but do you have a chart like this that shows fuel pump trims range and adv? I have no clue if 1.4 is good or bad.

 

[Doubeleive]

looks like some knock is kicking in around 3500 rpm and up under a load, uploading a video I guess efi plays it back at like 1/10 the speed

 

[Doubeleive]

 

[Doubeleive]

I have no idea what is normal for engine knock, here is what mine looks like

 

[mikez71]

saw a max of 13.4 deg knock retard in your first photo.
video shows you staying in knock retard.. I know what it feels like!

should be 0 knock for the most part..

check motor mounts, starter, anything close to the knock sensors that could be rattling..

 

[Doubeleive]

saw a max of 13.4 deg knock retard in your first photo averages..!

ya, is that bad? I don't know anything about knock or how much is normal or bad.

 

[j91z28d1]

unless it's been changed max knock retard is 10deg and I didn't see it hit that so while it would be nice to have zero, seems like something the ecm can get on top of, or it would be maxed out retard..

I still am not clear even own truck if the timing shown is the actual timing with the knock retard removed or if that's like the base timing and you gotta remove the say 5-7deg in your head.


either way I don't believe that's why it's running bad but hopefully black bear will know if they need to reduce tuning a bit or let the ecm do its thing