M50, Can't hold idle... Yes, I searched...

[NedMW]

I have an M50NV, it starts but won't idle without a mild input from the accelerator.

I've pulled the the ICV and cleaned that but it didn't solve the problem, so what I'm asking is can you help me suggest/rule out possible candidates for this fault.
Car may have head problems and had been sitting for a few months before I got it, but I shouldn't think this would effect the ability to hold idle... then again I am a noob!


CPS
TPS
Fuel Filter
MAF (oh please god no, I have a NV M50 and they are NLA or $$$)
FPR
Vacuum Leak (where?? What are the common failures?)
Spark Plugs
Oil(?)
Bad gas
anything else???

Preferably cheap (and relatively easy) fixes eg. general maint just to get it running. Could I seafoam?

Thanks

Ned.

[HlyDvlz1989]

think of the fuel pump yet?

[uk525td]

start with the obvious icv (done) vacuum leaks, o2 sensor
look for oil in water or water in oil, or overpressurising of hte cooling system (ie overflowing) as a basic diagnosis on hg failure
depending on how long its been stood oyu may want to put fresh petrol in

[NedMW]

think of the fuel pump yet?

Nope cause the car runs consistenly

[yaofeng]

Check the curved rubbed hose with square pattern ribs under the intake behind the throttle body is firmly seated. It should have a snap hook to lock onto the intake.

[NedMW]

Check the curved rubbed hose with square pattern ribs under the intake behind the throttle body is firmly seated. It should have a snap hook to lock onto the intake.

That was my first thought so I checked it when I did the ICV and it seemed all good unless it's got holes in it... Any other vacuum lined that'd cause these kinda symptoms?? Would a cam position sensor cause problems like this?

[yaofeng]

There is another smaller diameter vacuum hose between the intake and the fuel pressure regulator. The more apparent one is of course that from the PCV to the ribbed rubber hose I described to you earlier.

[Mordan]

IF there are no other symptoms, I would say a vacuum leak.



I would check the spark plugs conditions and spray StartPilot around the injectors, intake gaskets and hoses while watching for idle changes. Major Vacuum leaks are easily found with this method.

[NedMW]

Is there a way to test the FPR?? So this smaller diameter hose can just be bought by the metre down at a parts store? No need for special BMW hose?

Where exactly do you recommend spraying the startpilot? Just around the intake manifolds and vacuum hoses? to see if it sucks it in and changes the idle?

[yaofeng]

You can use a US spec vacuum hose for replacement. It is made of soft rubber.

[whiskychaser]

This may be a cheat but why not turn the throttle stop screw a tad just to stop it stalling while you sort it out?
I know you have cleaned the ICV but does it buzz? AFIK that indicates it is at least working. Isnt there a test where you move the ICV manually to open or shut and see if it moves to mid position when you turn on the ignition?

[NedMW]

Well when I pulled te ICV from the car it was at it's mid position so I reckon I works, the new suspect is the fuel pressure regulator I'm gonna test that mother sometime soon... 45.3psi at idle and 51-ish under load... I've followed a few vacuum hoses and all seem to be atleast attached to their respective points but whiter they leak at the unions is another matter... Fuel filter is on the hit list too cause it's cheap!! $12 FTW

[NedMW]

Well when I pulled te ICV from the car it was at it's mid position so I reckon I works, the new suspect is the fuel pressure regulator I'm gonna test that mother sometime soon... 45.3psi at idle and 51-ish under load... I've followed a few vacuum hoses and all seem to be atleast attached to their respective points but whiter they leak at the unions is another matter... Fuel filter is on the hit list too cause it's cheap!! $12 FTW