tunning M30 to best idle

[grave77]

this has been an issue for a long time but I still cat get to a final answer about it ... I just need to know if the AFM is not tunning for smoothest idle at a cirtain point but to unscrew the pot. and move it up a bit, but when full throttle the engine cuts off at 5300RPM, does this mean that the AFM is dead !! I also noticed that the spring is getting loose !! if I kept the spring where is it, the pot goes up and down and rpm sinks as if the engine is going to stop.

I made a vaccume check and was all ok ... I already have a good O2 sensor ...

if there are some steps to fine tune the engine to the max torque and smoothest idle I would be happy to know for sure ...

thanks ...........

[Jeff N.]

Sorry. I can't follow what you are trying to do. If you have taken the AFM apart and the spring has slipped, you likely have ruined the AFM.

There's not much idle adjustment options on the M30. You have to absolutely make sure you have no vacuum leaks. You have to have an ignition system in good condition - wires, cap, all that. You try blasting out your ICV with sensor safe carb cleaner if you want; sometimes they can get sticky when old.

The air pot bleed on the afm is like the final step after you ensure all the major items are working well.

Most peoples problems with idle seem to be related to vacuum leaks.

[grave77]

well ... I have marked the spring in the AFM before changing the position ... I'm planning to change it anyway since the resistive line has got a groove already. I have checked for leaks and all small pipes are new. ignition system could be old now ... dist. specially ... ICV ... is that the Idle control valve? I washed it with W40 and made sure its not stuck.the whole question is ... whould I still have the idle misbehaviour even after replacing the AFM ?if you still expect leaks .. where should it commonly be else than plastic hoses.Thanks Jeff ...

[genphreak]

well ... I have marked the spring in the AFM before changing the position ... I'm planning to change it anyway since the resistive line has got a groove already. I have checked for leaks and all small pipes are new. ignition system could be old now ... dist. specially ... ICV ... is that the Idle control valve? I washed it with W40 and made sure its not stuck.the whole question is ... whould I still have the idle misbehaviour even after replacing the AFM ?if you still expect leaks .. where should it commonly be else than plastic hoses.Thanks Jeff ...Dude, run the AFM back to stock position. I ran mine up 3 notches previously (we talked about it back then) but it gave a result only whilst i had a vacuum leak (ended up being from the pan gasket). Since I tightening the loose pan bolts it ran better, but still had bad economy soi my attention was turned back to0 the AFM (everything else is new). Ran AFM back to stock position (still unsure if the spring has changed due to age or not) and economy improved - perfromance unchanged. I have to get a new AFM too, but it will go when I get round to installing the SplitSecond PSC001 or a Megasquirt so till then it it is making do... :) Nick

[grave77]

well ... I went today to a scrapyard picked up a test AFM from a car .. seems very clean and I just pluged it in since mine is mounted upside down for tunning... the surprise was it's not different ..and I still got the rough idle ... I switched the car off ... and coolent level showed on ... I added water in ... and turned it on again ... after some time .. I didnt feel much pressure in the pipes ... installed my old AFM ... sounds the same ... drove it back home ... and the lovely surprise was ... I have an engine with chockolate mixure ... yummy :P ... engine needs something else here ... and here goes my new post (http://www.bimmer.info/forum/showthread.php?p=118021#post118021) .... :(