2006Tahoe2WD
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I ended up ordering this one.
CEL came on yesterday, 2006 ODB trouble codes
- Thread starter 2006Tahoe2WD
- Start date
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2006Tahoe2WD
Full Access Member
For those still here. I have massive good news. The EVAP status finally cleared after not much driving. Right now - I/M status clear and no codes except the HVAC air/fresh air actuator is not happy with a P code. I'm working on that along with engine coolant temp. hot reading steady or correctly.
Mudsport96
Full Access Member
On the cutting the floor topic. I did that on my old 2 door S-Blazer, as dropping the tank on it was a pain with the aftermarket( see homemade) skid plates. But I did go to the junkyard and cut a larger patch piece to put over the hole. It actually overlapped each side by a good 2 inches. Would not do to my current Tahoe as it is still virtually rust free. But 10 years from now, all bets are off lol
2006Tahoe2WD
Full Access Member
I probably won't consider cutting the floor but it is tempting. Consider the downsides of dropping the tank down compared to a cut in the floor.
2006Tahoe2WD
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Water temp. sensors. I think I have two sensors. They should read (ohms) similar as the engine warms up or at least track each other. This might confirm that it is not the fault of the sensor for the gauge. I did see mentioned somewhere that the connection via the treads on the gauge can get corroded and provide false resistance readings.
I'd find it hard to believe that there are to ECT sensors. Where would the second one be located?
2006Tahoe2WD
Full Access Member
I saw mentioned in a couple places that there were 2. One drives the gauge and the other ? goes to the ECU. I thought it was odd also. I looked this morning but not very well. I did see the one on the front of the drivers-side head.
I did fill the overflow tank a bit about an inch above the "joint" to see if something will change. I don't see the "line" that is supposed to be the cold-fill line so I filled until I could read cold-fill easily.
I did fill the overflow tank a bit about an inch above the "joint" to see if something will change. I don't see the "line" that is supposed to be the cold-fill line so I filled until I could read cold-fill easily.
On mine the cold fill line is the seam between the two halves of the surge tank. "Full Cold" is molded into the upper half, with an arrow pointing down to the seam.
My owner's manual conflicts and shows a line about 3/4" below the seam, marked Full Cold.
Either one should be fine as long as you use the same one for reference, especially when you are monitoring suspected coolant loss.
My owner's manual conflicts and shows a line about 3/4" below the seam, marked Full Cold.
Either one should be fine as long as you use the same one for reference, especially when you are monitoring suspected coolant loss.
2006Tahoe2WD
Full Access Member
Yesterday I added coolant to about 1" above the seam when the engine was hot and heater settings were on max. Today the temp. is rock steady at about 195F. I need to test it on a longer drive with some downhill sections. That would be good if adding coolant fixed the issue. A bit embarrassing but still good.
2006Tahoe2WD
Full Access Member
I went on a drive (over highway 17 and back) and the temp. stayed steady. The temp. did drop a bit on 5-6 mile downhill but not much. I think filling and burping the cooling system did the trick. If that's it - the easiest fix I've ever completed. At this point the DIY gods owed me that.
No new codes are showing up. However, I do see my long term fuel trims are at +9% during idle. I don't think the fuel filter or fuel pump has ever been changed (180k miles). I'm considering doing a fuel pressure test to start with. Also I plan to rig up my scanner with long and short trims showing and drive around to see if the engine goes lean requiring more positive trim.
No new codes are showing up. However, I do see my long term fuel trims are at +9% during idle. I don't think the fuel filter or fuel pump has ever been changed (180k miles). I'm considering doing a fuel pressure test to start with. Also I plan to rig up my scanner with long and short trims showing and drive around to see if the engine goes lean requiring more positive trim.
If the positive trims at idle is something that just started happening, re-check the intake plumbing. If the intake tube between the MAF and the throttle body has any leaks, that will cause unmetered air to enter the system (like a vacuum leak). What are the short term fuel trims looking like when the LTFTs are positive?
Agree to document the fuel pressure with the standard tests. Regulated fuel pressure should be around 43-45 psi at idle.
A couple other things to check with a warm engine:
- read the MAF g/s at idle, that should be approximately the same as the engine displacement in liters (e.g., 4.8, 5.3, etc.)
- read the short term fuel trims at idle, then at 1800 or 2000 rpm. If they're very positive at idle but go down with higher rpms, start looking for a vacuum leak.
- are the upstream O2 sensors reacting and voltages moving between 0.1 and 0.9v?
2006Tahoe2WD
Full Access Member
Thanks much for this.
Yesterday I ran the engine in the driveway watching the LT and ST trims. The short term trims were bouncing around 0, e.g. up to the range of +/- 3% but mostly +/- 2%. The LT trims were +9 and +10 and then went to both at +9%.
I will retest per your instructions and borrow the fuel pressure test kit from Autozone. I have a fuel pressure gauge but I don't think I have the right adapter.
Thanks again.
The connection on the passenger fuel rail is a large Schrader valve. Like a bike tire valve (not Presta style) but bigger.
2006Tahoe2WD
Full Access Member
This is funny. I looked at the Harbor Freight fuel pressure kit. I had a strange feeling like I've been in this place before. I went up into the attic looking at my seldom used tools collection - sure enough I have a HF fuel pressure test kit that is unopened. So I'm ready to dig in - tomorrow or the next day.
2006Tahoe2WD
Full Access Member
At idle my scanner reads 0.01 lb./sec. and 2400 Hz. I don't see a grams/sec. option.
I went on a drive and watched the LTFTs. Nothing too crazy - some 4-5 and a couple times +10%. I need to dive in and take a fuel pressure reading.
I went on a drive and watched the LTFTs. Nothing too crazy - some 4-5 and a couple times +10%. I need to dive in and take a fuel pressure reading.
strutaeng
Full Access Member
On scanners where you can't change units, simply "Google" 0.01 lb/sec to grams/sec.
My google search says: 4.53 grams/second.
You could figure out conversion factors, but this easier. I think my Innova handheld scanner gives lb/minute units ...
2006Tahoe2WD
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My error. I was able to change the units on my scanner. MAF reading 5.3-5.4 g/s.
2006Tahoe2WD
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Major update re. fuel supply/trims.
I extend the fuel pressure gauge and taped it to the windshield. It held very steady 59-60psi all the time. Is this too high? I could not see a regulator. Is there one? I drove on a few steep grades and the pressure did not move. At the same time I watched the LT and ST trims. When I got onto a steady grade the LT trims might read 4-5 or maybe a bit higher - sometimes reading zero. The ST trims were up and down passing zero.
I also graphed the MAF and it went up and down according to my feeling on how much air should be going in. I think no worries at this point on the MAF functionality or signal.
I extend the fuel pressure gauge and taped it to the windshield. It held very steady 59-60psi all the time. Is this too high? I could not see a regulator. Is there one? I drove on a few steep grades and the pressure did not move. At the same time I watched the LT and ST trims. When I got onto a steady grade the LT trims might read 4-5 or maybe a bit higher - sometimes reading zero. The ST trims were up and down passing zero.
I also graphed the MAF and it went up and down according to my feeling on how much air should be going in. I think no worries at this point on the MAF functionality or signal.
2006Tahoe2WD
Full Access Member
I read somewhere that the fuel spec. is 60 psi +/- 5 psi
2006Tahoe2WD
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It looks like I have the non-return type fuel system and it is not a Flex engine. I think that helps limit what the fuel pressure should be.
