2006 5.3 2WD Tahoe missing going up hill sometimes

[MassHoe04]

you can have injectors cleaned on the vehicle at many shops they just connect directly to the fuel rail and run the cleaner thru them instead of fuel usually cost about $80-90
but you can find decently priced injectors on herko automotive they have a regular website and they also sell on ebay

Herko Fuel Injector INJ560 For Chevrolet GMC Avalanche 1500 Express 1500 02-07 | eBay

Herko Automotive INJ560 OEM 25326903. New in Herko Automotive Box. Chevrolet Avalanche 1500 2005 5.3L 323Cu. V8 FLEX OHV Naturally Aspirated. V8 GAS OHV Naturally Aspirated. Replace Faulty Fuel Injector.

www.ebay.com

WOW! I was expecting $40-$50, but $24? Those are great price!

 

[2006Tahoe2WD]

I got my Foxwell Scanner today and hooked it up and ran the engine in the driveway.
The O2s seem to go up and down along with short term fuel trims. Nothing looked out of place while looking at the live data. The Foxwell seems to have a pretty good set of capabilities. The response to pressing the buttons is a bit slow but not bad. A pro would not like it.
I need to try some on road testing with my son driving and see what might be happening under load.

 

[2006Tahoe2WD]

The next number of posts might be questions regarding what I see on my new scanner. E.g. what I see on the graphs of O2 sensors, short term fuel trims and Long Term Fuel Trims. Any misfires/etc.
Should I start a new tread or continue here? I figure there are actual techs on this forum. I appreciate all the the info/input so far. Right now the engine seems to run fine and no check engine lights. There was a air conditioning door error. That's it.

 

[2006Tahoe2WD]

Okay. I've been reading about looking at scanner outputs. E.g. short and long fuel trims, MAF, O2 sensors pre and post cat. So far I've checked all that in the driveway and everything seems to be in spec. Maybe the LTFT is reading constantly e.g. +7%. I need to do some more testing. There are no CELs. The upstream O2 readings are bouncing between .2 and .8 or so but they are not bouncing the same, one seems to be lazy.

 

[Fless]

The upstream O2 sensors should vary between 0.1v and 0.9v, and they may not vary the same at the same time. It's easier to see when they're graphed, but if they're moving the full range, active, and not fairly static they're probably okay. If you suspect one, use your graphing scanner to see their activity better over time (it looks like you can graph). You can swap the upstream sensors side to side to see if the suspected laziness follows, but at that point if they have any significant age on them, consider replacing them with new quality sensors.

You should have STFT and LTFT values for both banks. Bank 1 is the driver's side. The STFTs are what is happing NOW and will move around; that's what the engine computer does to adjust things, but ideally they should be between ±5% during normal driving. They'll go higher with acceleration, at least for a few seconds while you're on the throttle. Once they swing wider and stay near 10% either way is when you want to start looking for causes. LTFTs are just STFTs over time; if your STFTs are less than ±5% I wouldn't worry about it. Short term trims reset with each ignition cycle, but long term trims are just historically accumulated short term trims; think of them as a moving average or a trending value. If ST trims are nice and low, the LT trims will eventually reflect that; and the converse is true.

 

[2006Tahoe2WD]

The upstream O2 sensors should vary between 0.1v and 0.9v, and they may not vary the same at the same time. It's easier to see when they're graphed, but if they're moving the full range, active, and not fairly static they're probably okay. If you suspect one, use your graphing scanner to see their activity better over time (it looks like you can graph). You can swap the upstream sensors side to side to see if the suspected laziness follows, but at that point if they have any significant age on them, consider replacing them with new quality sensors.

You should have STFT and LTFT values for both banks. Bank 1 is the driver's side. The STFTs are what is happing NOW and will move around; that's what the engine computer does to adjust things, but ideally they should be between ±5% during normal driving. They'll go higher with acceleration, at least for a few seconds while you're on the throttle. Once they swing wider and stay near 10% either way is when you want to start looking for causes. LTFTs are just STFTs over time; if your STFTs are less than ±5% I wouldn't worry about it. Short term trims reset with each ignition cycle, but long term trims are just historically accumulated short term trims; think of them as a moving average or a trending value. If ST trims are nice and low, the LT trims will eventually reflect that; and the converse is true.

Yes I can graph. I guess I could take a picture of the graph with both upstreams on the same graph or one above the other. With 172k miles maybe it is time for new upstream O2s. Then the question becomes go to the dealer or dig to find what make/model of O2 is good and plays nice with the original ECU.

 

[Fless]

Others will have recommendations on O2 sensor brands for your '06.

Will your scanner look at individual cylinder misfires? If so, that might help the diagnosis along with the corresponding fuel pressure reading. You'll need to be prepared for that and have everything set up in anticipation of the issue.

 

[2006Tahoe2WD]

There seems to be quite a few posts on the web regarding the intake manifold gasket going out. Anyone replacing that before it goes bad? It seems when they do it they replace the knock sensors/seals and the harness going to the knock sensors.

 

[2006Tahoe2WD]

Others will have recommendations on O2 sensor brands for your '06.

Will your scanner look at individual cylinder misfires? If so, that might help the diagnosis along with the corresponding fuel pressure reading. You'll need to be prepared for that and have everything set up in anticipation of the issue.

My scanner has live selection of each cylinder misfires. I bought a fuel pressure meter and I would have to extend the hose and tape the gauge to the windshield I guess. How does the ECU know when there is a misfire? It sees an O2 go way rich?

 

[rockola1971]

My scanner has live selection of each cylinder misfires. I bought a fuel pressure meter and I would have to extend the hose and tape the gauge to the windshield I guess. How does the ECU know when there is a misfire? It sees an O2 go way rich?

O2 sensors cant tell which cylinder is acting a fool since there are only 2 sensors. One for each bank. (Excluding the post cat sensors which have nothing to do with a/f ratio). Either somehow the knock sensors can tell which cylinder is the culprit(s) or there is flyback voltage on the cylinder(s) individual ignition coil(s) that are acting up and the PCM senses that. Interesting question though. One that ive never thought of. Now I MUST know the answer too!
My tech Tech 2 shows each cylinder in a list of 8 and then misfire counts in real time. IE: Cylinder 1 0001 Cylinder 2 0000
Very handy to see whats going on especially when spark plug wires are old but dont show any actual defect but are the reason there are misfires galore.