Bmw Help? Anyone Clued Up.

[Richie-Van-GTi 70 2 Cars]

Sorry I know its a 205 forum.

I have a 1998 E39 523i. Its got the M52B25 single vanos 2.5 engine, straight 6. It is having real issues with idling. :-

 

From cold it wont idle, you have to blip the throttle constantly or just restart when your ready to pull away, annoying at junctions!, when it starts to warm up it will kind of idle at about 3-400 rpm, although it sounds kind of like it drops a pot or 2, occasioanlly picking itself up. There is an occasional 'pop' inside the inlet somewhere which is 'random' in the way it happens. When driving the engine is sweet, pulls really well and fires on all pots etc.

So far Ive checked all intake and pipes etc for leaks and all is well. Ive replaced the idle control valve and the cyclone valve (oil breather diagphram) with new genuine BMW parts along with spark plugs. Ive ran a compression test to find all pots are spot on and within 5 psi of each other right across. Ive even replaced the DME(ecu) without any change. There are no fault codes to go off either. Ive already ruled out TPS and MAF sensors.

Im stumped with it now. Anyone had any experience with these?

Edited June 17, 2009 by Richie-Van-GTi

[MrG 3]

richie

 

try here >> 5 series board a UK site to and either it's a sensor thats packed up or they'll know more.

 

You say the compression tests are OK but are they within tolerances to what BMW expect them to be? If so then that rules out the Nikasil issue then as this sounds like an issue to do with that, but if this was the case you'd have little or no compression when warm on many pots.

[Richie-Van-GTi 70 2 Cars]

Its not nikasil issue, the engine has just been replaced due to nikasil issue. Ive managed to track it down to a faulty injector O ring or the manifold gasket right behind it. If I concentrated a squirt of carb cleaner on that very area there was a distinct difference in idle quality. The manifold is in the garage now as we speak with some new gaskets and liquid gasket smeared in the gaps drying before I refit it tomorrow morning. I got tomorrow off so now have the time to strip and resolve