Starachell
Member
Hello all. I'm currently suffering from the dreaded rough idle and I'm at a complete loss what to do next. I have a 2011 n52 2.5 manual which I purchased last July from an independent dealer. After being attracted to the car for its low mileage and pristine bodywork, it has now turned into the worst car I've owned. I've listed the main points here for brevity but it's worth noting that in between this issue, I've had to replace a bodged trailing arm, remove the adaptive suspension and a broken spring following an MOT fail, install a b12 kit, repair the solenoids on the trunk and change the battery. I say that to point out the rough idle issue has been there for a while but feels like it's getting progressively worse because I'm now driving the car more consistently whereas between Oct - Feb she was in and out of the mechanics for these other issues.
Main codes pulled by our code reader and that of the specialist:
POOBC
2D06
Symptoms:
-The car will stall in neutral or in first gear when waiting to move off at a light/roundabout
-The car will also attempt to stall and then will rev itself back to life - this is less frequent
-The rev counter and temperature gauge bounce when the car is stationary. This rev hunting often pre-empts the above issues happening, though sometimes the car dies with no warning. The worst experience I've had was in nose to tail traffic for an hour and a half and the car either died, or dropped the revs and then revived itself, 16 times.
-Occasionally, upon restarting, the car seems to shake and whirr
-Having the air con on makes all of the above worse, particularly the shaking/whirring
-Heavy/rough handling below 3000 revs whereby the car feels sluggish and it takes a lot of work to get a response. For example, I might be in 4th gear doing between 30 -40mph and the car computer can be saying go up to 5th and I'll have to drop to 3rd to get some engagement and steady things. Interestingly, I feel this issue is worse when the engine is warm rather than at startup. I can start a journey well, get stuck at a long light, the car dies and then for the rest of the journey I will feel like I'm pushing the car to get home.
-I end up often dropping gear to increase the revs to eliminate that feeling that the car is about to die
-The car bunny hops at low speed/revs and at higher speed will almost skip a beat before resuming
-Increase in fuel consumption - no surprise given that I'm dropping gears
-Exhausts are coked
-edited to add: car now has EML but no new codes
-Completely unrelated I'm sure but the alarm has now started to go off in the rain. I've seen the issue with the microsensors in the door card so we're going to assume that's a bonus gift.
As I said above, this is all happening more frequently. However, I have days where I drive the car and she behaves herself and I'm left wondering if it's a figment of my imagination. Other days I look like I can't work a clutch. Typically, the good days are when she's on the ramp or being driven by a tech to find the issue! As a daily driver, it's getting to the point where I don't feel safe and I find myself taking different routes home to avoid long traffic lights or steep hills where I may need to stop for cyclists etc.
Here's where we're at with the diagnostics and fixes:
-I had a new MAF sensor fitted under warranty when the issue first started. I've since had that replaced just in case the part was faulty or the work wasn't done. This made no difference whatsoever.
-We've cleaned the MAP sensor which seemed to improve things for 2 weeks but at this point, that could also be down to the moon being in the right position with a favorable wind
-Smoke test didn't show any leaks
-We've just cleaned the Vanos solenoids with no real difference. The morning after the solenoids were cleaned, the rev needle seemed stable but by the time I drove home she was stalling again
-Battery changed
-The specialist's best guess is that the fuel pump needs changing but they have been very honest to say it's an educated guess and they're only about 50% sure this is the right direction. That assessment is down to the 2D06 code indicating a lean mix. With all the work done so far, I need more certainty than that. I would also expect some of the long crank issues. From what I've seen, fuel pump isn't high on the list of culprits for this issue.
In my naive mind then I've got a list of potential suspects:
-Vanos solenoids need replacing and the cleaning wasn't enough, though they did whirr into action afterwards
-Fuel pump
-Sparks and coil packs
-DME
-Oil pump as I've seen some people talk about the lack of a proper seal
I know there are lots of posts about this here but I've struggled to find one that had the idle without clear misfire or long crank. I'd be immensely grateful if anyone could share a similar story - particularly if you have a positive outcome that doesn't start to stretch into the four figure territory.
Main codes pulled by our code reader and that of the specialist:
POOBC
2D06
Symptoms:
-The car will stall in neutral or in first gear when waiting to move off at a light/roundabout
-The car will also attempt to stall and then will rev itself back to life - this is less frequent
-The rev counter and temperature gauge bounce when the car is stationary. This rev hunting often pre-empts the above issues happening, though sometimes the car dies with no warning. The worst experience I've had was in nose to tail traffic for an hour and a half and the car either died, or dropped the revs and then revived itself, 16 times.
-Occasionally, upon restarting, the car seems to shake and whirr
-Having the air con on makes all of the above worse, particularly the shaking/whirring
-Heavy/rough handling below 3000 revs whereby the car feels sluggish and it takes a lot of work to get a response. For example, I might be in 4th gear doing between 30 -40mph and the car computer can be saying go up to 5th and I'll have to drop to 3rd to get some engagement and steady things. Interestingly, I feel this issue is worse when the engine is warm rather than at startup. I can start a journey well, get stuck at a long light, the car dies and then for the rest of the journey I will feel like I'm pushing the car to get home.
-I end up often dropping gear to increase the revs to eliminate that feeling that the car is about to die
-The car bunny hops at low speed/revs and at higher speed will almost skip a beat before resuming
-Increase in fuel consumption - no surprise given that I'm dropping gears
-Exhausts are coked
-edited to add: car now has EML but no new codes
-Completely unrelated I'm sure but the alarm has now started to go off in the rain. I've seen the issue with the microsensors in the door card so we're going to assume that's a bonus gift.
As I said above, this is all happening more frequently. However, I have days where I drive the car and she behaves herself and I'm left wondering if it's a figment of my imagination. Other days I look like I can't work a clutch. Typically, the good days are when she's on the ramp or being driven by a tech to find the issue! As a daily driver, it's getting to the point where I don't feel safe and I find myself taking different routes home to avoid long traffic lights or steep hills where I may need to stop for cyclists etc.
Here's where we're at with the diagnostics and fixes:
-I had a new MAF sensor fitted under warranty when the issue first started. I've since had that replaced just in case the part was faulty or the work wasn't done. This made no difference whatsoever.
-We've cleaned the MAP sensor which seemed to improve things for 2 weeks but at this point, that could also be down to the moon being in the right position with a favorable wind
-Smoke test didn't show any leaks
-We've just cleaned the Vanos solenoids with no real difference. The morning after the solenoids were cleaned, the rev needle seemed stable but by the time I drove home she was stalling again
-Battery changed
-The specialist's best guess is that the fuel pump needs changing but they have been very honest to say it's an educated guess and they're only about 50% sure this is the right direction. That assessment is down to the 2D06 code indicating a lean mix. With all the work done so far, I need more certainty than that. I would also expect some of the long crank issues. From what I've seen, fuel pump isn't high on the list of culprits for this issue.
In my naive mind then I've got a list of potential suspects:
-Vanos solenoids need replacing and the cleaning wasn't enough, though they did whirr into action afterwards
-Fuel pump
-Sparks and coil packs
-DME
-Oil pump as I've seen some people talk about the lack of a proper seal
I know there are lots of posts about this here but I've struggled to find one that had the idle without clear misfire or long crank. I'd be immensely grateful if anyone could share a similar story - particularly if you have a positive outcome that doesn't start to stretch into the four figure territory.
