What did you do to your NBS GMT800 Tahoe/Yukon Today?

[strutaeng]

@strutaeng Your positive fuel trims are what's causing the lean code that lights the money light (CEL); positive trims means the PCM is adding fuel. Ideally the sum of each bank's LT and ST trims should be 5% or less. What are your short term trims after it warms up, and what is the sum of ST and LT on each bank?

For example, Bank 1 LT is 10% and ST is -6%: 10 + -6 = 4%. Or -6 + 10 = 4%.

If the LT trims are way higher than the ST trims, then you may want to have the LT trims reset with a capable scanner. It takes the LT tables a while to adjust to ST trims that are significantly different.

10% (total) isn't bad, but anything over that is something that should be investigated. Adding 20% fuel that isn't getting burned can burn up your cats if you have them.

If the trim on both banks is high I'd be looking for a crack or loose hose on the intake tube after the MAF or some kind of vacuum leak, something that affects both banks. Another less common cause is a leaky injector, which can be checked with an injector balance test.

Thank you. Sometimes the short term do go a few points negative, but the sum is still well over 10%.

I've done a smoke test of the intake, but didn't see anything. I cleaned my MAF and actually changed it from another similar I own suburban and not much change. The idle readings lb/min(?) of my scanner convert pretty close to 6.0 grams/second. The rise in values seem good and linear with throttle increase. The other sensor data such as ECT, MAP, etc. also seem okay as well as far I can see

I also did an injector balance test and all injections were within 1-2 psi of each other.

 

[Tonyrodz]

Received today. Didn't realize how bad the balancer looks and this WP is fairly new, but been off 3x due to head issues a couple years ago and previously had clutch fan.
View attachment 413446View attachment 413447View attachment 413448

Can't wait to swap to the electric fans. How'd you run the factory fan harness? Do you have a pic? I also bought the correct underhood fuse box. I might as well do it.

 

[mattbta]

Can't wait to swap to the electric fans. How'd you run the factory fan harness? Do you have a pic? I also bought the correct underhood fuse box. I might as well do it.

LT has a pretty good video. I ran them similar.

 

[Tonyrodz]

LT has a pretty good video. I ran them similar.

Thanks for the link.

 

[Mudsport96]

So far its money well spent.
It's like a totally different truck. Even sounds different. Power is there when you need it, there's no surging of the idle--and no idle chop--which is fine with me. View attachment 411300
It was tuned using a Mustang dyno. Looks to be 345 rwhp and 355 tq. Not too bad.

Glad it all got straightened out man!

 

[Mudsport96]

Home sweet home.View attachment 411409

Wait you have a Panther platform too? My parents just sold theirs without telling me or I would have e bought it from them. 03 Grand Marq with 73k on it. Rode like a dream. The 4.6 was a little weak in my book buy it ran smooth as silk. Was a beautiful burgundy/maroon with cream interior

 

[Tonyrodz]

Wait you have a Panther platform too? My parents just sold theirs without telling me or I would have e bought it from them. 03 Grand Marq with 73k on it. Rode like a dream. The 4.6 was a little weak in my book buy it ran smooth as silk. Was a beautiful burgundy/maroon with cream interior

Yup, I have the same color combo-- actually it's torreador(sp?)red with stone interior, It's the Sport LX, with the center console and floor shifter. Pretty quick. It's actually my most reliable car--and I'm trying to sell it to get a Mustang notchback.

 

[ivin74]

Can't wait to swap to the electric fans. How'd you run the factory fan harness? Do you have a pic? I also bought the correct underhood fuse box. I might as well do it.

I did electric fans on my son's truck and it was pretty straight forward. The most expensive part is getting then tune to the ecm.

 

[Tonyrodz]

I did electric fans on my son's truck and it was pretty straight forward. The most expensive part is getting then tune to the ecm.

I already have mine tuned, just gotta swap them out now. I think for me, the most challenging part will be to remove the clutch fan. I did it once on my van tho. If facing the front of the vehicle, is the thread for the clutch fan reverse or regular thread? Whack it to the right or to the left? I forget which.

 

[ivin74]

I already have mine tuned, just gotta swap them out now. I think for me, the most challenging part will be to remove the clutch fan. I did it once on my van tho. If facing the front of the vehicle, is the thread for the clutch fan reverse or regular thread? Whack it to the right or to the left? I forget which.

Rent the removal tool from Autozone, not hard to remove w the tool