Rough idle garage stumped!

A

AlpinaBoy

Member
As per my logon I have a 2005 Alpina roadster s

Car booked in with rough idle speed which you can both see on the rev counter and feel in the car

It's circa 700 to 800 rpm

Performance seems fine and no other issues

First thing they replaced was the throttle body and no change

I told them to check the throttle position sensor and they said that would show on the diagnostic if failed

I am concerned it could be head gasket mileage is circa 75000 just in the region

They will get back to me next week

Fingers and toes crossed its to too big a bill.....
 
Check the idle control valve, it may just need a good cleaning. Check for air leaks in the intake pipes, especially the large bend with a smaller side inlet. It may be worth getting a new coil pack or two and swap out the old ones in turn until an improvement is noticed. May as well put in new plugs just because. I wouldn't worry too much about the head gasket unless you've had a significant overheating event. Anyway, a compression test to check is fairly easy to do.
 
Where's Swiftly?

Think he had a problem of running which ended up being vacuum in the fuel tank due to a small pipe needing replacement?

Last posts sounds good advice.

Let us know if you get a solution.

:driving: :thumbsup:
 
I had an intermittent rough idle problem about a year ago, could go for a few days or even a week then it would start again including bringing the management light on :headbang:

Do you have any error codes stored? The error code on mine was 'P0171 'system too lean bank 1 which is a bit generic to say the least and can point to a number of issues so I was told.

You need to go back to basics, remember too lean = air getting in or fuel starvation, and try an eliminate the obvious first. After over 4K worth of AUC work done and 5 months of pain, the culprit turned out to be an intermittent fault with the fuel tank breather valve, causing a vacuum to build up which hindered the supply of fuel :roll:

A couple of videos I managed to capture at the time of the car rough idling

[youtube]kX376zeyiW0[/youtube]

[youtube]C9ah3V34IJ4[/youtube]

This is the journey I had and the parts that the dealer changed after numerous tests and under advice from BMW UK and Germany which thankfully were all covered under AUC

Rocker Cover Gasket
Inlet Manifold Gasket
Fuel Pump
Fuel Pressure Regulator
Fuel Pressure Sensor
Fuel Filter
Mass Air Flow Meter
Exhaust Manifold
Fuel Tank Breather Valve
 
I experience something similar on my car as well (it's only on 38k), a slight dip in tickover speed felt though the gearstick and a tiny blip on the rev counter, it only happens when hot and it smooths out if I add load to the engine - e.g. switching on the aircon. Performance is absolutely fine and, as it's not throwing any fault codes, I'm not particularly concerned - I have BMW warranty so they won't do anything until it gets worse and throws a fault code

If the compression test comes back OK, other things to investigate include
- a coil pack on it's way out
- vacuum leak
- MAF
- cam position sensor
- the O2 sensors
 
BMW dealer just phoned and have ordered a new General Module

This will according to them solve all my issues including non functioning hand brake warning light

Although personally i cant see how the module will affect the running of the car??
 
AlpinaBoy said:
BMW dealer just phoned and have ordered a new General Module

This will according to them solve all my issues including non functioning hand brake warning light

Although personally i cant see how the module will affect the running of the car??
Click to expand...
Please keep us informed of the result :thumbsup:
 
AlpinaBoy said:
BMW dealer just phoned and have ordered a new General Module

This will according to them solve all my issues including non functioning hand brake warning light

Although personally i cant see how the module will affect the running of the car??
Click to expand...

Hopefully it resolves the problem, however I am with you on this one as I am not sure how the module would affect the rough idling
 
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