good ol' it cranks but won't start thread

[Ill 3.0]

Hey everyone, been a while

I know there are a bunch of these threads, and mine might just be a bad coolant temp sensor. But since I have an O2 sensor code figured I'd run it by the experts so I don't waste too much time/resources. So here is the issue:

For the last few months I've had a progressive difficult to start issue ('02 A4 3.0 manual trans). The car will crank but won't start until 12-20 cranks. Has a rough idle for the first 30 seconds to minute then it runs just fine. Lots of smoke and unburnt fuel initially and sometimes revs to 3k RPM for the first minute unless I put it in a higher gear to put a load on it. I do hear the fuel pump whine with key to on position and after the first couple of minutes it will run flawlessly. No CEL but I finally got around to scanning it and got 17585 code, "bank 2 lambda correction downstream of catalyst: control limit attained"

For what its worth, I have JHM tune and JHM downpipes with relocated HFCs. Houston requires inspection with emissions, so I probably have to replace the O2 sensors anyway. But I wanted to see if it makes sense if having a bad "post cat" O2 sensor (which is really still upstream of the cat b/c of relocated high flow cats) would cause such a start up problem. I've also sent a message to JHM to make sure my O2 sensor code and failed readiness isn't normal with their tune and downpipes (I don't think it would be), in which case it wouldn't be contributing to my starting issue, but would be something I still need to figure out.

Thanks for any insight

[FrankenA4]

While I'm not a genius with the 3.0, it almost kind of sounds like a leaking injector. If it took a long time to start, and you smelt unburnt fuel when it did start, my assumption would be that it's dumping fuel into one or more cylinders and may have gotten to the point that it's flooded itself. Just a thought to inspect the injectors.

I don't believe that the O2 sensors would have much bearing on the startup as they're primarily there to make adjustments while the engine is running, not during start-up.

Sorry I can't be of more assistance.

[SJorge3442]

The rear o2's do NOTHING to the fueling of the engine. They simply report how well the cats are working.

This sounds like some sort of air leak or air issue. I know when my MAF was dirty it was a bitch to get started. Cleaned that and we were good. The extra revs could be being applied to help keep the engine from stalling as the ECU knows the car is having issues. How old is your crank position sensor? This could be causing some issues. Sorry im not more help, but this issue is certainly strange.

[imnuts]

Sounds like you have one or two (maybe more?) potential problems. You could have a leaky injector that isn't fully closing causing excess fuel to spray into the cylinder, leading the fuel smells. You may also have a spark issue, preventing the fuel from igniting, also leading to the same issue of fuel buildup in the cylinders. Your problems are not due to the tune, and I can't see the HFCs or O2 sensors causing the problem. The ECU should ignore the O2 signals when starting, and the rear O2 sensor shouldn't do anything with your fuel injection. I'd go through and check that all of the fuel injectors are working properly, and after that, check the spark plugs to ensure that they all have spark.

[Ill 3.0]

Wouldn't an injector issue alway be present and not just at start up?

Could be the MAF, I'll clean it. Though I've had issues with the MAF before and it caused a code.

Crank position sensor is original. Could be the issue, but I thought that also caused stalling issues?

Helpful to know the O2 sensor issue is not contributing,
Thanks for the help so far