2007 running rich on bank 2

[03GMCYukonXL]

I have an issue with my 2007. When it's under 70 degrees outside, I'll get a rich on bank 2 code. But ONLY when I just let off the gas to coast down a hill or at idle. No CEL usually, just the stabilitrak light. It always goes back off after a few seconds. It never lasts. If it's warmer outside I'll never get the code. I've replaced all injectors with AC Delco on bank 2. It seemed to have helped it not be so frequent.

So if I have it under load going up a hill, once I peak the hill and coast down, the stabilitrak light comes on and it's that code. Once it's been about 30 seconds or I put it under load again it goes aways. Only when it's around 70 degrees or lower outside. Also, once the truck gets really warmed up after driving a good 15 minutes or more, it stops doing this. I really don't think it's actually rich either. It's really annoying because it makes the truck shift hard. Could this be an 02 sensor? There are literally no other codes that come along with this either. No 02 codes, but I've heard they can do this sort of thing without being bad enough to throw a code.

 

[Fless]

I would suspect a vacuum leak. Vacuum is much higher with low throttle or when idling, and that can suck in unmetered air. You could look at your short-term fuel trims at idle, then again at 2000 rpm to see if there is much of a difference.

Visual inspection might show a vacuum hose or connection that is compromised.

It might also be good to see if your upstream O2 sensors are working properly; that's easiest to see with a graphing scan tool.

 

[j91z28d1]

what's the code? and what's the date showing while it's happening? even a cheap scanner should show you the fuel trims while it's happening.

when you decel like that, it should be in decel fuel cut, injectors closed and o2 sensors read dead lean.


do you have any broken off exhaust manifold bolts on that side? it's very common to pop a few over time.

 

[03GMCYukonXL]

what's the code? and what's the date showing while it's happening? even a cheap scanner should show you the fuel trims while it's happening.

when you decel like that, it should be in decel fuel cut, injectors closed and o2 sensors read dead lean.


do you have any broken off exhaust manifold bolts on that side? it's very common to pop a few over time.

I have an hp tuner but I still am learning how to read things. I can get a read of me going down the road. Funny thing is, I have a broken exhaust manifold bolt on the bank one side. It's never given any issues before though. It's the very back one. I replaced my pcv hose a few months ago because it was cracked.

The code is P0175. It's strange because it won't do it for weeks and then it'll do it every couple days for about a week then go away again.

 

[03GMCYukonXL]

I would suspect a vacuum leak. Vacuum is much higher with low throttle or when idling, and that can suck in unmetered air. You could look at your short-term fuel trims at idle, then again at 2000 rpm to see if there is much of a difference.

Visual inspection might show a vacuum hose or connection that is compromised.

It might also be good to see if your upstream O2 sensors are working properly; that's easiest to see with a graphing scan tool.

Wouldn't a vacuum leak make it run lean?

 

[j91z28d1]

with hp tuners you can setup logging for the o2 sensors on both side and all then fuel trims, also should be a flag for dfc. give you something to compare, also I believe hp will show the freeze frame data from when the code will set. but you'll have to Google to make sure. if so, it will gave you a snap shot of what all is going on when it sets.

 

[Marky Dissod]

Wouldn't a vacuum leak make it run lean?

Only in Open Loop.
In Closed Loop, the O2 sensors would notice that the MAF is consistently lean.
The constant enrichments could be big enough to significantly change the LTFTs,
yet not quite big enough to cross the trouble code threshold.

 

[03GMCYukonXL]

Only in Open Loop.
In Closed Loop, the O2 sensors would notice that the MAF is consistently lean.
The constant enrichments could be big enough to significantly change the LTFTs,
yet not quite big enough to cross the trouble code threshold.

Aside from the PCV hose, where else could there be a vacuum leak. I don't really see any other spots aside form the EGR pipe and that doesn't seem to be leaking at all.

 

[Marky Dissod]

In theory, anywhere between the MAF & the O2s. In your case, it's passenger side.
If you don't find anything with your eyeballs, it's likely the intake manifold.

 

[Fless]

But get a look at the O2 sensor activity and the fuel trims; they may lead you in another direction. A smoke machine might be helpful if those tests point to a vacuum leak, or unlit propane around the intake manifold and other vacuum connections to see if the engine idle changes.

 

[B-train]

Have you ever replaced the MAP sensor? If so, I've sewn sensors for the wrong application/generic give that sort of issue with traction control light coming on and off

 

[03GMCYukonXL]

So update. This issue went away with warmer weather. I thought maybe the problem fixed itself lol. However, now with the cooling weather, the issue has returned. Now the real funny thing is, it seems to do it the worst between 50 and 70 degrees. When it's real cold, it isn't as bad, but still present. In the heat it's never present.

It's only at idle, or once it's been under load at speed and then I let it coast. As in climbing a hill and then coasting down. Once I give it throttle and it's under load again, the light goes out. So it makes sense what was previously mentioned about a leaking gasket causing a lean condition and the compensation from the ecu puts it in a rich condition once the rpms are down. I actually have a set of metal intake gaskets that came with my Texas speed DoD delete kit. I'll swap these out in the coming weeks and see if that helps

 

[Discodisco]

You really need to get fuel trims before you can do anything, since it’s only on one bank it’s somewhat isolates what you need to look at but it could be anything from a vacuum leak to an injector to a o2 sensor.

 

[Fless]

You really need to get fuel trims before you can do anything, since it’s only on one bank it’s somewhat isolates what you need to look at but it could be anything from a vacuum leak to an injector to a o2 sensor.

Add to that an exhaust leak on that side as @j91z28d1 posted.

 

[Discodisco]

Yeah an exhaust manifold or gasket leak could certainly introduce post combustion air into the exhaust before the sensor making it think it’s running lean and richening it up.

 

[03GMCYukonXL]

Funny thing is, I have a popped exhaust manifold bolt on bank one. Bank 2 bolts are fine. If it was a bad 02, wouldn't it throw a code? The service stabilitrak light literally only comes on at idle or after I've been driving under load and then let it coast.

 

[Discodisco]

Funny thing is, I have a popped exhaust manifold bolt on bank one. Bank 2 bolts are fine. If it was a bad 02, wouldn't it throw a code? The service stabilitrak light literally only comes on at idle or after I've been driving under load and then let it coast.

you got an oil pressure issue my friend, im willing to bet that you also have a p0111 stored for the variable cam timing. when your sitting at idle oil pressure is probably low and when you come off a heavy load to no throttle it dips too.

To further answer your question though, its hard to say without fuel trims, the PCM is designed to set a fault once a certain value is exceeded in a binary matter, simple yes or no, the fuel trims though can vary anywhere from -9% to + 9% (roughly) without setting a fault.

 

[03GMCYukonXL]

you got an oil pressure issue my friend, im willing to bet that you also have a p0111 stored for the variable cam timing. when your sitting at idle oil pressure is probably low and when you come off a heavy load to no throttle it dips too.

To further answer your question though, its hard to say without fuel trims, the PCM is designed to set a fault once a certain value is exceeded in a binary matter, simple yes or no, the fuel trims though can vary anywhere from -9% to + 9% (roughly) without setting a fault.

You may be correct except for one thing. I don't have variable cam timing but I do have an oil pressure issue that has been present since I did the DoD delete. I'll get the p0521 code sometimes. The oil gauge goes to 0 and gives me the warning and when I give it a bit of gas it goes back up and stays that way. That too only comes about when the weather is less hot. That only happens every now and then. The service stabilitrak light and CEL for p)175 happens daily. I was told that I have the oil pressure issue because I didn't change the oil pump to a low volume high pressure one.

Why would an oil pressure issue cause a rich condition in one bank?

I have a file of the truck running at idle and the stabilitrak light comes on at some point and I give it some throttle and it goes away. Problem is, it won't let me attach the file here.

**EDIT** Side note, I have a flex fuel and was told to look at my alcohol percentage and couldn't find it, but I did discover that the flex fuel was disabled. I did not to it.

 

[Fless]

You may be correct except for one thing. I don't have variable cam timing but I do have an oil pressure issue that has been present since I did the DoD delete. I'll get the p0521 code sometimes. The oil gauge goes to 0 and gives me the warning and when I give it a bit of gas it goes back up and stays that way. That too only comes about when the weather is less hot. That only happens every now and then. The service stabilitrak light and CEL for p)175 happens daily. I was told that I have the oil pressure issue because I didn't change the oil pump to a low volume high pressure one.

Why would an oil pressure issue cause a rich condition in one bank?

I have a file of the truck running at idle and the stabilitrak light comes on at some point and I give it some throttle and it goes away. Problem is, it won't let me attach the file here.

**EDIT** Side note, I have a flex fuel and was told to look at my alcohol percentage and couldn't find it, but I did discover that the flex fuel was disabled. I did not to it.

You can upload a video to a hosting site like YouTube, and post a link to it here.

 

[03GMCYukonXL]

You can upload a video to a hosting site like YouTube, and post a link to it here.

It's a hp tuners file not a video.