Another P2187 thread

[Hupa]

Hi guys&gals. My 2.0tfsi, BUL engine has engine light eith error code P2187-running lean going on and off. Sometimes it stays away several days. OBD11 shows long term fuel trim >6%, short term around zero. When I erase the code, engine almost dies and short term trim shoots to 25-27%. Then the values slowly return to about the same values as before the code erase. I checked the hose starting from booster, intact, can’t blow through it, doesn’t hiss. The next hose to vacuum pump has small (superficial) cracks at ends, and the socket to the vacuum pump has 1-2mm up/dowm play when engine is off. I thought the cracks or the socket was the leak, but as engine runs, the vacuum sucks the socket firmly down. It doesn’t jump around like in some videos I’ve seen. When I spray engine starter on/around this vacuum hose/pump socket, there is no change in rpm, nor any up/down peak in the short term fuel trim (there should be if the hose was sucking in air, right??) I’ve sprayed engine starter at/around all air hoses/connections, around the the PCV and breather hoses… with no rpm/fuel trim response. One thing still points to something being off with the brake vacuum, as when I press the pedal long it starts slowly going down and the rpm strats to climb well over 1000 (or is this normal?). The booster still seems to hold vacuum, as the depressed pedal doesn’t force itself up when turning off the engine. Any Idea what this is about? Could this be connected to lead idle error code?
If this was exhaust leak, should the engine react so strongly to erasing the code and resetting fuel trims? I mean, the mixture isn’t actually lean if the leak is in exhaust, or what is the chain of events then? I’m out of ideas, what should I check next. I have the cam chaing replaced next week at the shop and they’ll take a look at the lean idle issue, so no emergency. I’d just like to find the fault before I take the car to the shop.

[Jayz691]

Which LTFT is +6%, idle or partial. Since you say it slowly rises after clearing codes, I'm guessing idle trims? If so, that almost def points to a vac leak. PCV is a common cause, or any crack hoses/pipes for the PCV(front or rear).
A smoke tester might help ya find it.
As for the brake pedal, I feel that's kinda normal.

Sent from my CPH2611 using Audizine Forum mobile app

[Hupa]

Idle ltft settles to around 6%. I tried to look for the air leak by spraying engine starter along air hoses, edoevially around junctions, pcv, vacuum pump & hoses, intake manifolf, throttle body, basically all around the engine. I get no clear peak in rom or stft anywhere. They should react strongly (at least stft) if flammable stuff gets sucked in, right?
I know the vacuum pump nipple connection is bad as it has up/down play, but I get no stft or rpm response even when spraying directly at it or at the hose, so I guess it seals itself under vacuum.
One thing about the PCV, I keep reading mixed info on if there should be significant crank vacuum at idle. Some say, the PCV is faulty if there is strong vacuum, and others just the opposite. Which way is it? My car has quite a strong suction when I lift the oil cap or the oilstick and rough running starts. Logic suggests that there should be intake manifold vacuum if at idle the pcv opens path to crank case, rigt/wrong? But still, even spraying around/at PCV& its vac. hoses&junctions gives no change in rpm or stft. Are there more channels numbers (or groups as vcds calls them) I should follow trying to pinpoint the source, should it not be an air leak. Also, acceptable ranges for the respective signals would be appreciated! 😁 I have obd11, but the groups/channels are the same as in vcds, right? I use that for reference, as I can’t find the obd11 channel info anywhere. At least these channels 32/33 seem to hold the same info as vcds.

BTW, yeasterday, after 3hours of futile search for the air leak, I decided to fo something useful for a change, and change the summer wheels. Noticed I had misplaced the 17mm socket, and spent 2 furious hours trying to find it in the garage… with no luck, of course. What a frustrating day that was. Had to drink a few more beers than intended. 🤣

[Sapphire]

Hello, I'm French, so please forgive my poor English :)

I'm happy to see that I've FINALLY found someone in the same situation as me. I don't think we have the same engine code (CDNC and you BUL), but I have an absolutely identical problem. 27% lambda correction at idle, with a P2187 fault code. No engine light, however, for me. The big problem for me: EVERYTHING has been done on my engine: PCV valve and its hoses, intake gaskets and valve cleaning, N80, ultrasonic injector cleaning, timing belt & its associated housings and gaskets, phase shifter, oil tube, lambda sensors and flow meter, throttle valve cleaning... NOTHING seems to be able to solve this remaining 27%. A month ago, I had a P2279 and a P0507 with the P2187, but they were resolved by replacing my front main seal (I went from 60% correction to 27%). However, with the corrections, my idle speed no longer seems to jump at all and is perfectly stable.

Same thoughts as you about the braking system!!! If I press the brake pedal several times, my idle speed will start to "float" around 1200 RPM! If it helps, I already tested the brake booster by plugging the large hose that runs from the vacuum pump to the hose that goes to the brake booster with a large screw (we must not have exactly the same architecture), but in any case, no change for me! Also, on the 2.0TFSI, the braking vacuum is managed by a vacuum pump and not by the intake manifold vacuum. So I still don't understand why pressing the pedal raises the idle speed... it's strange... I asked my dealership in France, but they seem too incompetent to answer me... Perhaps you could try it yourself?

Regarding your question about the PCV, I can't answer you because I don't know the vacuum values ​​for your engine. For mine, 100mBar, or 3inHg, which is already enormous! So my oil cap is firmly seated on my rocker cover.

By the way, for my part, it's worth noting that if I disconnect the hose that goes from the IM to the PCV and plug it with my hand (therefore, no more vacuum in the engine), I only go from 25-27% to 20%! So, theoretically, at least 20% of the correction would come from the intake? Now, everything is new and tight... The last thing I need to check: The gasket between the catalytic converter and the turbo, which is right next to the lambda sensor that makes the corrections. I've already seen several cases on this engine where this gasket was completely disintegrated, and therefore the lambda sensor detected excess air.

I remain available to discuss with you the various work/progress you can do to resolve your problem.

[Hupa]

Hi Sapphire, nice to hear from you, though you too are in trouble. What’s the mileage of your car? Have you ever changed the fuel filter? I too need to change it, as it has filtered away 264000km. I just had the cam chain&tensioner replaced. The terrible noise went away, but didn’t help with the lean idle condition. Do you have a code reader? If so, what does it show for coolant temperature? Mine shows 95-97C, although the instrument cluster gauge sits firmly at 90C. Could this have something to do with the problem? I do have a medium coolant leak at the back of the engine. I have checked the fuel pressures wile driving… low pressure ~4.5bar (reacts somewhat to throttle), high pressure ~50bar. To me these values look ok.