e30m42 idle issue

[bimmer9]

hi guys, five months after my car went thru the m42 conversion, my first prob has come up.Here's what happens, everytime I start the car everything is normal, when i give it a bit of gas it starts idling roughly (like its on 3 cylinders) and hesitates to move/rev. So what I need to do is give it a good hard rev for about 30 secs and everything comes back to normal. No problems at all while driving, it only happens when I start the engine.But apart from that, I have noticed slight power loss, as in the car hesitates slightly and feels somewhat heavy? But then again that might be just me used to the m42 nowMy mechanic reckons its the spark plug cables, I am going to try on some second hand ones.But somehow I dont think thats the problem, correct me if im wrng but if it was the plug cables it will happen erracticaly at any time. But this only happens when I start the car. Weird ayy?Sifu's pls advise!Thanks

 

[fabianyee]

were u at Alexis last Sat night for Sharizan's performance???

ok, back to topic. Can be a lot of causes. Can be the coil pack having problem. Shouldn't be the plug cables if it's an intermittent problem..
Anyway, when it's idling roughly in the morning, test by removing the plug cable one by one to see if really it is running on 3 cylinder.
See also whether there's oil leaked into the spark plug chambers.
Can also be sticky idle control valve.
or sticky AFM barn door..
Time to check one by one...
hopefully it's not a fried DME. Have you done any welding (exhaust, body) lately?

 

[bimmer9]

nope fabs last sat nite I was at home. Must have go the wrong person.

Anyway, what I have recently done (last week):
-Got my car serviced
-CLEANED IDLE CONTROL VALVE
-REPLACED AFM WITH A USED ONE (FOC from my mech since the last one I bought from him during my conversion was faulty).
-welded a crack on my oil sump. (but it was taken out and sent for welding so I doubt it would have fried anything)

So Im guessing it has to be with the AFM or Idle Control Valve.

Whats the best way to check?
I think its the AFM lazy door or whtever its called.

 

[bimmer9]

Also, I have been told that my centre box require replacing, dalam sudah kosong.

That might explain the light jerking I get at low speed but I dont think it has anything to do with this start up problem.

Correct me if im wrong.

Sheesh man, ure like the m42 wikipedia.

Thanks a lot.

 

[fabianyee]

these are not specific to M42 lah.. same things can apply to other engines...

 

[bimmer9]

so bro, how do I make the AFM 'more active'

is it advisable to spray lubricant?

 

[McFir7]

i got same problem b4..but after i change knock sensor, exhaust sensor n icv..nvr have the problem again..but in ur case maybe u dont need to change all that..maybe 1 or 2 only..

sometime even when u scan for fault code..it would not appear..so what u got to do is..u got to check the voltage reading..if is not changing regularly while u rev or the reading is out of spec that suppose to be..then u can try to clean it..but if still doest solve that means needs to change the parts..

in my case no fault code..but the reading was out of spec..after replacing wit new parts..reading back to normal spec..

thru my observe.on m42 u got to watch on this

1.leaking (air or oil)
2.dirty or spoilt sensor or electrical parts
3.worn out air hose

this 3 things u got to watch out..cause these problems could make the m42 really really sux..
if u solve this 3 problems..u will really enjoy the hell out of m42..then u will know why some ppl love the m42 so much hehehehe...

 

[bimmer9]

i got same problem b4..but after i change knock sensor, exhaust sensor n icv..nvr have the problem again..but in ur case maybe u dont need to change all that..maybe 1 or 2 only..

sometime even when u scan for fault code..it would not appear..so what u got to do is..u got to check the voltage reading..if is not changing regularly while u rev or the reading is out of spec that suppose to be..then u can try to clean it..but if still doest solve that means needs to change the parts..

in my case no fault code..but the reading was out of spec..after replacing wit new parts..reading back to normal spec..

thru my observe.on m42 u got to watch on this

1.leaking (air or oil)
2.dirty or spoilt sensor or electrical parts
3.worn out air hose

this 3 things u got to watch out..cause these problems could make the m42 really really sux..
if u solve this 3 problems..u will really enjoy the hell out of m42..then u will know why some ppl love the m42 so much hehehehe...

Hi McFir7,

Thanks for your reply.
In my case my knock sensor and exhaust sensor was replaced during my conversion. ICV cleaned and put back but the problem still persists. Now I need to check AFM and check work air/vacuum leak.
I do realize some power loss which I think is related to the problem.
If u dont mind me asking how much was the ICV you replaced? Did they have the part in stock?
Will make a trip down to my mechanic this Friday and hopefully sort it out, supposed to shoot to Penang this weekend but need to fix this first otherwise tak shiok la.

Will keep u updated.

cheers