11’ Camaro V6 gdi. P2099

Have code p2099 post cat fuel trim system high bank 2. Tsb for this problem says most likely injectors. My verus doesn’t have injector balance testing for this year. 

Car has 99k miles. No exhaust leaks, no exhaust back pressure, no vacuum leaks, fuel pressure is good, slightly rough idle, new O2’s, bank 2 fuel trim around +6 / +10 total. Not sure what to do since I can’t do a balance test on the injectors. 

Testing before throwing parts at the problem is what this forum is about.

Your Camero sits low so getting under to do testing on those 02's is a challenge.
If the downstream is reporting rich, the upstream has to be doing the same. The values you cite are not what you would expect for this code. Are your STFT and LTFT the same for both banks?

Test the 02's the easy way first. Pull a vacuum hose. Do the trims go positive? Introduce an alternate fuel source, propane is the best, or brake cleaner into the intake. Do the trims go negative?

Just so we're all informed, does this car have two cats?

Yes this car has 2 cats and separate exhaust all the way back. Fuel trims on bank 1 are pretty near 0. Watching upstream O2’s while driving and they both are reacting very similar. Although bank 2 upstream is slightly slower sometimes in amplitude or reaction time.

Comparing downstream O2’s bank 2 does go through its full range like bank 1 but it is way slower to react especially at slow speeds. If I really step on it and get the cat hot it reacts faster but will still not react correctly more than half the time. Bank 1 will be at 720mv while bank 2 will be stuck around 200mv etc. I do believe a bank 2 cat efficiency came up once so the cat is possibly going out. 

Going to scope the injectors and see if I can find anything. Tsb and Mitchell did state that replacing O2’s will have no effect on this code unless you have heater circuit codes etc. 

Here’s some snapshots while running

You could to an injector test the traditional way pressure drop with a pulse tester and pressure gauge.
 

This is direct injection so not really feasible. Injectors are buried in a very tight spot. Need the engine running so the hpfp runs. Just really no way to do it without the scan tool.

I wouldn't sweat the lack of a balance test on your scan tool. I've had multiple GM vehicles with injector problems, and the automated balance test didn't help to diagnose any of them. In other words, even if you get a scan tool that'll run the balance test, I don't think it'll show a problem.

The O2 captures you posted are much more informative, IMO. Would you mind sending me the .SCM file? wrenchturnsyou@gmail.com.

I definitely wonder about the cat not storing oxygen correctly. You're positive there are no exhaust leaks?

Is scm like screen recorded videos? I only took snapshots.

Despite this code saying bank 2 rich it actually means it’s for a lean condition the computer is correcting rich. Positive 10% fuel trims on bank 2.

I smoked the exhaust a few times stone cold. I also pressurized the exhaust and used soapy water. No leaks. Also back pressure tested the cat and it was near 0. I’m leaning towards carbon fouled injector tips. It did have a catalyst efficiency code bank 2 briefly. Both cats are same temp inlet and outlet.

wrote:

Is scm like screen recorded videos? I only took snapshots.
 

.SCM is one of the formats Snap-On uses for the scan data capture files. I don't know what it actually stands for. :silly: Nothing wrong with your screenshot, just wanted to dig a little further into the data if it was available.

The trims on bank two could definitely be caused by a injector spray pattern problem. It could also be caused by the downstream fuel control system adding fuel to get the downstream O2 to act right. I wonder, if you clear codes and hit the Fuel Trim (Reset) in Functional Tests, how quickly do the trims go back to where they were?