Rough idle - driven mad

ori said:
That’s a promising lead.

A reading that far out would 100% cause running issues.
Concern is, is it a sensor or cabling issue?

Exactly that, or is it something within the DME. Best case scenario is a sensor that's gone rogue and is lying to the DME. Where that sensor is though is another issue. The previous owner used the car so infrequently that I worry about wiring as well, though I think the car was, at least aesthetically, protected..
 
B21 said:
If the coolant temp is reading that number then that will probably throw a spanner in the works..probably massively rich…?

Absolutely, she smells rich and the exhaust is coked. I can also go through fuel like I'm getting kickbacks from the oil execs. I feel this is probably the closest I've gotten to the pieces fitting together. The previous suggestion of a fuel pump and the intermittent nature didn't seem to gel.
 
Starachell said:
B21 said:
If the coolant temp is reading that number then that will probably throw a spanner in the works..probably massively rich…?

Absolutely, she smells rich and the exhaust is coked. I can also go through fuel like I'm getting kickbacks from the oil execs. I feel this is probably the closest I've gotten to the pieces fitting together. The previous suggestion of a fuel pump and the intermittent nature didn't seem to gel.

On the N20 engine failure of that sensor causes those issues, appreciate it’s not the same engine but…
 
Might be a good time to go buy a decent code reader - it’s a 5 minute job to see exactly what that sensor is doing.

Takes some of the guesswork out of the equation.
 
matsmith749 said:
Might be a good time to go buy a decent code reader - it’s a 5 minute job to see exactly what that sensor is doing.

Takes some of the guesswork out of the equation.

We're using Veepeak with Bimmer Link at the moment. The coolant sensor is fine and temperatures are normal. What we saw yesterday was something about ambient temperature to the DME so perhaps not coolant. The tech said he wasn't sure which sensor was giving the reading and whether it was actually embedded in the DME. They're going to call me on Tuesday with more of the specifics about it. They've suggested plugging it into ISTA to explore it further.
 
B21 said:
Starachell said:
B21 said:
If the coolant temp is reading that number then that will probably throw a spanner in the works..probably massively rich…?

Absolutely, she smells rich and the exhaust is coked. I can also go through fuel like I'm getting kickbacks from the oil execs. I feel this is probably the closest I've gotten to the pieces fitting together. The previous suggestion of a fuel pump and the intermittent nature didn't seem to gel.

On the N20 engine failure of that sensor causes those issues, appreciate it’s not the same engine but…

Just need to find the sensor that's at fault. I've also seen people say the -40 is an indication that the wiring has failed. I just hope the sensor isn't embedded in the DME.
 
What of the ambient temperature sensor, front left, bottom of wheel arch.
My cars went faulty, can't remember now why i changed it, but it had failed.
I think it went to -40c open circuit? I think roof stopped working.

I need to keep a diary.
 
flybobbie said:
What of the ambient temperature sensor, front left, bottom of wheel arch.
My cars went faulty, can't remember now why i changed it, but it had failed.
I think it went to -40c open circuit? I think roof stopped working.

I need to keep a diary.

I feel like I need a diary at this point as well, if only to save me from going crazy! At the specialist yesterday the car didn't die at all. We've just been out to run the coder and it died 4 times :headbang: However, we did manage to read the ambient temperature from the wheel arch sensor and it was absolutely fine. We can't see where the ambient temperature in connection to the DME stems from.
 
I wanted to jump on with an update of how things are going – or not, as is the case. Sparks and coil packs are all fine and operating as they should. I took the car to a second specialist for another opinion. They checked the DME for damage, none found, and reprogrammed the VVT as this was incorrectly stored in the car. I picked it up but the issue remained - rev and oil counters bouncing at idle and then the car stalled shortly after pulling into a parking space. Took it back to the same garage who then fitted a new temperature sensor but again, no luck. I’ve since taken the car to the dealership I bought it from and they've taken it to BMW. They claim BMW tested the car on the ramp for 2 hours and it didn’t fault, road tested it twice without issue, and of course the car didn’t die on the journey to or from the dealership. I’ve emphasized to them numerous times that it’s not the road testing that’s the issue, it’s the pulling over and stopping which then throws everything else off. I know the MAF fault code (2D06) was still showing when I dropped the car off so how BMW have explained that away I do not know. The dealership I bought the car from have left me with some particularly brilliant suggestions – am I sure it’s not just the stop/start even though the car doesn’t have that function and am I sure I’m not just trying to drive away from a red light in 2nd gear…… Next step is to take the dealer out for a test drive so that he can experience what’s happening. I’m really looking forward to more top tips from him in the process.
 
Grasping at straws, but it sounds like it's something to do with an idle setting.
No expert on the N52, but does it have an idle control valve like the M54.
 
enuff_zed said:
Grasping at straws, but it sounds like it's something to do with an idle setting.
No expert on the N52, but does it have an idle control valve like the M54.

I don't believe it does because of the vanos system. This is something I'm happy to be corrected on though! It feels like it's an idle issue in the sense that the car is either not regulating the mix properly and choking itself, or it's cutting off because it's getting erroneous information somehow.
 
No ICVs on an N52. Valvetronic takes care of all that.

FWIW the temperature sensor in the wheel arch is just for the dashboard display. The DME uses a sensor in the MAF for intake (effectively ambient) temperature. I've just noticed they've been changed so possibly a pin has been dislodged in the connector.

I still say air leak. The PCV system is a notable area for these.
 
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