CEL came on yesterday, 2006 ODB trouble codes

[Fless]

I read somewhere that the fuel spec. is 60 psi +/- 5 psi

That would be for the initial test with KOEO (key on, engine off); according to Haynes it should be 55-62 psi for non-Flex Fuel.

Idling, I'm not sure what yours should be, but the ones like mine that have the FPR on the fuel rail run in the mid 40s (~43 or so).

I think around 2005 they started putting the FPR in the fuel pump module:

 

[2006Tahoe2WD]

Yes, the systems with the regulator near the intake are able to lower the pressure at idle (high vacuum). It seems my system (no return from the rail area) is more of a constant pressure type. At this point I'm thinking to back off trying to fix my "high" LTFTs. One thought is the MAF is dirty and reading such that the ECU wants to add fuel after looking at the O2 sensor readings. Not sure exactly how this works. There are a number of inputs:
- original map
- MAF, temp(s), rpm, TPS
- O2 sensor readings

 

[2006Tahoe2WD]

The focus now will be on replacing the fresh-air actuator which appears to be the only remaining error code. There are a number of YouTubes on this. My current thoughts are:
- remove the dash cover, doesn't look too hard
- maybe remove or pull the air bag to the side
- cut the ducting to get at the actuator
- replace the light sensor while I'm in there

 

[2006Tahoe2WD]

Fless, if you are still here. I took the two belts off the front of the engine to measure the runout of the HB. See me on another thread. When I started the car there was a loud and unmistakable clicking. Usually my Tahoe idles almost perfectly quiet. What is going on? Nothing seems to be wrong with the belts or any pulleys.

 

[2006Tahoe2WD]

Fless, if you are still here. I took the two belts off the front of the engine to measure the runout of the HB. See me on another thread. When I started the car there was a loud and unmistakable clicking. Usually my Tahoe idles almost perfectly quiet. What is going on? Nothing seems to be wrong with the belts or any pulleys.

I guess no need to panic. The ticking noise went away. Still I don't like that it happened. Like a lifter got hung up. That should not happen because I don't have a variable displacement motor.

 

[2006Tahoe2WD]

Some interesting info. on harmonic balancers. My current conclusion is the "new" HB I have is out of spec. regarding radial runout. The wonders of Google turned up that there are companies that rebuild HBs. I thought these guys/gals should know what is going on regarding the runout. I was able to have an email exchange with the owner of one of these companies. I explained my concern and runout measurements. His response was the I'd probably be happy with an internal element damper. I won't mention names because I don't think we are supposed to. You all most likely know the name. Anyway my plan is to give up on getting a high quality typical HB and go with a "solid" with internal moving element type.
Also, regarding fuel pressure on my rig. I taped a pressure gauge to the windshield and got a steady 50 psi in all types of driving.

 

[2006Tahoe2WD]

The connection on the passenger fuel rail is a large Schrader valve. Like a bike tire valve (not Presta style) but bigger.

Fless, I've checked the fuel pressure while driving and cleaned the MAF. I'm still getting 10-15% positive LTFTs. Sometimes I get 7% under certain conditions. I'm thinking I have a heat sensitive vacuum leak. No codes but I don't like the high LTFTs. One thing I can think of is getting out my stethoscope and searching around for air leak sounds.

 

[2006Tahoe2WD]

I'll start a new thread for fuel trims.