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

[Doubeleive]

I am not sure to be honest as I am not sure which is the master.

Does the computer know when it wants to fire the spark and knows where the cam should be at that time and if it isn't there it throws a code, or does it wait for the cam to be in a certain position and then fire the spark which would not necessarily throw a code. I know if a cam position sensor doesn't sense a state change, it will throw a code because it thinks the cam isn't moving at all.

I do know that a bad VVT solenoid or valve can have an impact on fuel consumption.

well there is no misfires I have sat and monitored it with the tech2 and no misfire history either. the engine only has 40k on it, previous motor had a bad cam and my warranty covered a rebuilt motor and I paid the difference to the dealer about $1k to have a new factory motor put in only thing used on it was the intake and coils, fuel rail, power steering pump I had them put a new water pump on it at the same time so the water pump would have the mr goodwrench lifetime warranty. If my cat's aren't clogged or getting clogged then I don't know what else could be wrong it runs perfect. I replaced all 4 02 sensors at 100k which was 20k ago, i've serviced everything, put new plug wires on it about 3 weeks ago, the mileage was piss poor even before that

 

[wendal]

Met up with a fellow member today @dross99_si and attempted to find an emissions leak. Turns out the Tech-2 wanted the engine temp below 158 and that wasn't happening under today's Florida sun, even in the morning after a short drive. So instead we poked around the computer system and shot the breeze until next time. We're both chasing a P0442, very small evap system leak. The Tech-2 can be used to eliminate one portion of the system but I really need to make or buy a smoke generator and do a visual search.

Andy's 2007 Tahoe is one of the cleanest and well maintained trucks I've seen.

Oh, for you guys with Tech-2 and 2007 or 2008 trucks, where can you see the Fuel Pump Module or the pressure and such? Mine (2009) has a dedicated menu but did not see it on the 2007 and poked around a while and still couldn't find it.

If I missed an entry where you guys did this, my apologies; I've gotten way behind in this thread...

Did you guys change the purge valve?

I had a p0442, changed this valve in 5 minutes, error gone. My truck had been fighting to start on the first turn after filling up the gas tank. This resolved the issue and the error.

 

[wjburken]

well there is no misfires I have sat and monitored it with the tech2 and no misfire history either. the engine only has 40k on it, previous motor had a bad cam and my warranty covered a rebuilt motor and I paid the difference to the dealer about $1k to have a new factory motor put in only thing used on it was the intake and coils, fuel rail, power steering pump I had them put a new water pump on it at the same time so the water pump would have the mr goodwrench lifetime warranty. If my cat's aren't clogged or getting clogged then I don't know what else could be wrong it runs perfect. I replaced all 4 02 sensors at 100k which was 20k ago, i've serviced everything, put new plug wires on it about 3 weeks ago, the mileage was piss poor even before that

Man, you got me hanging on this one. I can't think of anything you have not covered. Only getting 8-10 mpg is very odd. Even in the winters here when we leave our vehicle run/warm-up, we average 13-14 mpg.

I only mentioned the VVT as I was getting ready to replace the solenoid and the valve on my 2007 because I was getting poor mileage and that was in the same boat as you. I actually purchased the solenoid and the valve, but ended up trading the vehicle in before I got to it.

If you do decide to go that route, now is the time to do it since your radiator is pulled and your coolant is drained.

 

[Doubeleive]

Man, you got me hanging on this one. I can't think of anything you have not covered. Only getting 8-10 mpg is very odd. Even in the winters here when we leave our vehicle run/warm-up, we average 13-14 mpg.

I only mentioned the VVT as I was getting ready to replace the solenoid and the valve on my 2007 because I was getting poor mileage and that was in the same boat as you. I actually purchased the solenoid and the valve, but ended up trading the vehicle in before I got to it.

If you do decide to go that route, now is the time to do it since your radiator is pulled and your coolant is drained.

if that is what controls the cylinder deactivation I have had that turned off with a canned tuner since the motor was put in

 

[wjburken]

if that is what controls the cylinder deactivation I have had that turned off with a canned tuner since the motor was put in

It does not have anything to do with cylinder deactivation. What I am referring to is the VVT solenoid and the valve for advancing/retarding your cam. I am assuming you still have VVT active in your vehicle. The valve doubles as the bolt that attaches your VVT phaser sprocket to the cam. The solenoid is mounted on the timing chain cover behind the water-pump.

 

[R3cord303]

Man, you got me hanging on this one. I can't think of anything you have not covered. Only getting 8-10 mpg is very odd. Even in the winters here when we leave our vehicle run/warm-up, we average 13-14 mpg.

I only mentioned the VVT as I was getting ready to replace the solenoid and the valve on my 2007 because I was getting poor mileage and that was in the same boat as you. I actually purchased the solenoid and the valve, but ended up trading the vehicle in before I got to it.

If you do decide to go that route, now is the time to do it since your radiator is pulled and your coolant is drained.

What engine do you have? My 07 doesn’t have VVT.



Unrelated but my MPG average sense replacing the engine and doing the AFM delete and cam hasn’t risen so far on the drive to California. Still at 14.3 but goodness the vehicle has been doing great on the drive.

 

[wjburken]

What engine do you have? My 07 doesn’t have VVT.

The 6.2L in the Denali's have VVT.

 

[Doubeleive]

It does not have anything to do with cylinder deactivation. What I am referring to is the VVT solenoid and the valve for advancing/retarding your cam. I am assuming you still have VVT active in your vehicle. The valve doubles as the bolt that attaches your VVT phaser sprocket to the cam. The solenoid is mounted on the timing chain cover behind the water-pump.

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i'm familiar with where it is located, I just wasn't sure if it had anything to do with cylinder deactivation or not. on the old engine I was getting 10 average, then when the new motor was put in I was getting 10, it's only sat on 8 since I reset everything in the dic and I have only been driving around town maybe 5-10 mile hwy drives at the most and the rest city driving, I need to go out of town a ways soon I may reset it again and see if it bumps off of 8, I think it's mostly just my spirited driving but not 100% sure.

 

[wjburken]

i'm familiar with where it is located, I just wasn't sure if it had anything to do with cylinder deactivation or not. on the old engine I was getting 10 average, then when the new motor was put in I was getting 10, it's only sat on 8 since I reset everything in the dic and I have only been driving around town maybe 5-10 mile hwy drives at the most and the rest city driving, I need to go out of town a ways soon I may reset it again and see if it bumps off of 8, I think it's mostly just my spirited driving but not 100% sure.

Fair enough. I thought your low mileage was a new development. You got let those ponies run on the open range once in awhile! Here in Iowa, we have a lot of wide open spaces to let them run.

 

[Doubeleive]

Fair enough. I thought your low mileage was a new development. You got let those ponies run on the open range once in awhile! Here in Iowa, we have a lot of wide open spaces to let them run.

well im going to keep an eye on it for sure, I need to pick up a thermometer and check the cat's at least that's easy enough