P2187 - system too lean at idle bank 1 - HELP!

Hey everyone, I’ve searched for countless hours on possible solutions for this CEL code but I need some advice.

2013 gti, awe turboback exhaust, unitronic stage 2, unitronic intake, r8 coilpacks, new spark plugs, new pcv, 117000km

I’ve have had zero issues up until a week ago. I had surging rpms and replaced my pcv valve because I figured the code was because of that. After replacing the pcv, the surging stopped, I cleared the code and it reappeared after a day.

On idle my vacuum is reading 10-12psi vacuum, boost is ranging between 18-20psi which is what I’ve always been having. I do not have vagcom (I’ve been reading it using the dash command app).

Under WOT, I am hearing a new noise around the front passenger side. Almost sounds like the turbo is shuttering and it sounds a bit louder than usual (yes it sounds nicer but it’s not normal). I thought it was a loose downpipe leak around the first o2 sensor but I took it to the mechanic and there was no leak at all.

My mileage has reduced ever since I got this code. (Usually get around 600km per tank) but now I’m barely hitting 500km and I do not have a heavy foot.

My next guess would be the o2 sensor that’s right after the turbo on the downpipe but I’m not too sure anymore on what else to look for.

I do not have any other codes, no misfires, no surging rpms, vacuum/boost seems okay...I’m stumped.

My mechanic suggested to replace the o2 sensor on bank 1 because that could possibly be the air fuel ratio sensor? (I don’t know).

Have not done carbon cleaning or throttle body cleaning yet either.

Any help is greatly appreciated!

Hopefully this helps.

http://wiki.ross-tech.com/wiki/index.php/18619/P2187/008583

Your vacuum is far too low. You really need to build or buy a pressure or smoke tester to check the system for leaks. Also, check for a vacuum leak at the rear main seal. I've had pcvs fail and kill the rear main seal, then after replacing the PCV the car will still run like crap at idle and throw codes because it's sucking in unmetered air.

Jiffyjetta said:

Your vacuum is far too low. You really need to build or buy a pressure or smoke tester to check the system for leaks. Also, check for a vacuum leak at the rear main seal. I've had pcvs fail and kill the rear main seal, then after replacing the PCV the car will still run like crap at idle and throw codes because it's sucking in unmetered air.

Click to expand...

Is it too low? My car is reading -10.7psi which is -21.7 mm/hg. I’ve looked around and it seems to be the normal amount.

I’ve heard of the smoke test for checking for leaks which I haven’t done yet. Are there any other symptoms of a failed rear main seal

hauluck said:

Is it too low? My car is reading -10.7psi which is -21.7 mm/hg. I’ve looked around and it seems to be the normal amount.



I’ve heard of the smoke test for checking for leaks which I haven’t done yet. Are there any other symptoms of a failed rear main seal

Click to expand...

I misunderstood your post. The negative psi reading threw me off. 21.7hg is fine for vacuum.
If the rear main seal is bad enough to cause idle issues, you should be able to hear it sucking in air from the bellhousing area. Try unhooking the large vacuum line from the intake manifold to the PCV and plug the intake manifold side. Then start the car. If the idle returns to normal, then you have a rear main or pcv issue.

Jiffyjetta said:

I misunderstood your post. The negative psi reading threw me off. 21.7hg is fine for vacuum.
If the rear main seal is bad enough to cause idle issues, you should be able to hear it sucking in air from the bellhousing area. Try unhooking the large vacuum line from the intake manifold to the PCV and plug the intake manifold side. Then start the car. If the idle returns to normal, then you have a rear main or pcv issue.

Click to expand...

I recently just changed the pcv due to idle surges approx 2 weeks ago. I will try to do the test to see if the rear main seal has failed but I’m not experiencing any kind of oil leaks.

I don’t have vagcom but I took a screenshot of my dashcommand app for certain readings, does anything seem weird/off.

Would an exhaust leak cause this issue? Mechanic recommended me to change my o2 sensor

Anyone please chime in

Your fuel trims are way too lean. You have a vacuum leak somewhere or b1s1 O2 is bad. 0 +/- 5 is ideal for fuel trims.
I wouldn't drive the car if it's that lean.

The picture got cut off... Is that bank 1 sensor 1, or bank 1 sensor 2 that is at 0.03v? Maybe post up some shots of both b1s1 and b1s2 if possible. A graph would be great. That way I can determine if it's a bad sensor or actually lean.

Would take a look at your intake to make sure everything is still tight. Would also check throttle pipe and turbo outlet pipe.

This guy made a left turn in front of me while I was driving straight and had to slam on my brakes. I was at a dead stop and probably 2 inches away from him and it just rattled everything. Few moments after that incident is when I was experiencing issues.

So the problem has been fixed. My intake clamps got loose and it was moving around a bit. Also found out that my downpipe cracked right where it connects to the turbo (that's the leak/turbo shutter I was hearing). Got the pipe welded all the way around and problem went away!

Thanks everyone for the help