More of less yeah so basically I have a vacuum leak on bank 2, which causes the o2 sensor and the lean code to pop up? I guess I'll start with the IACV the last time it was giving fits at idle I had blew the hose off. Any other ideas where to check?

 

An easy way to find your vacuum leaks is to apply propane around the intake manifold, injectors, etc. basically anywhere where air could possibly leak. At the same time watch your STFT. When you find the vacuum leak, it will instantly start dropping, followed by the LTFT. You can verify by taking the propane away. The STFT will immediately start back upwards.
If you still can't pinpoint it, you can spray a little water on it. You'll hear and see it sucking the water in. It will probably misfire a bit too. Good Luck! You'll find it.

 

STFT/LTFT whats that?

 

Short Term Fuel Trim / Long Term Fuel Trim
Most decent scan tools have at least a reading for them. The one I have actually has a graphing mode for each of them. Unfortunately, it will only let you use the graphing mode for one at a time. If I had to pick one for this application, I would use STFT. It gives the quickest response which helps pinpoint the leak.

 

or you could use carb. cleaner the idle goes up theirs your leak

 

OK, so I didn't need to put up the list of faults, but lets take stock of what we know i.e. the problem is only in one bank, 4 new sensors fitted and new 'Y' pipe fitted. This should help rule out some areas where leaks can occur but which are not the cause in this instance i.e. leaks anywhere between intake manifold/plenum chamber and MAF as any leaks here would affect both banks.

Having narrowed down the possible sources what's left, well there's the injector seals, it only needs one seal to leak for the O2 sensor on that bank to flag up a lean mix but this is unlikely unless the injectors on this side have been moved. then there's the joint at the manifold/down pipe or the exhaust manifold gasket.

When I had my D2 it didn't have SAI so I'm unfamiliar with it, if there was a problem there would it not affect both banks.

On the other hand it could still be a malfunctioning O2 sensor or sensor circuit.

 

also would 1st look at injectors for the leak

 

I was just joking about the list of faults. It may help some people, if that's what they're looking for.

If you suspect a malfunctioning O2 sensor, check to make sure that all are running just over and under stoich. If they are, they're good! I suppose you could watch the O2 data as well, it's just a little more up and down than the STFT which is pulled to zero by the LTFT. I'm going to guess that at least one LTFT is going to be at least +15 to +20. It may even have to be over +20 to set the code. If you are unsure of the sensors, just add propane straight to the intake, booster hose, anywhere really. If they're working, you'll see it for sure.

Oops. I missed part of what you were asking there about the SAI. It shouldn't have any effect in this case. At least, it's not very likely.

 

Well got around to looking at the truck today. Cranked it up and I have an exhaust leak at the manifold to the y pipe on the bank 2 side. Guess nuts get loose after being beat around a time or two. Going to get some lock washer and new nuts and see if that will help. Originally when I put the new y pipe on it was almost silent, and when the noise came back I was kinda glad I missed the aggressive sound. But I prefer what performance I get compared to the sound. Also checked the MAF and air filter but as already ruled out, because it would affect both banks not just 1. Thanks will let yall know of that was my problem or not.

 

The exhaust leak is a possibility. You may still want to verify with some propane. Definitely DON'T use carb. cleaner on the exhaust. This is why I only use propane, if you find a spark or flame all it will do is light the torch. Carb cleaner can leave enough unburned fuel to cause a possible fire.