Author Topic: 4000rpm troubles (Read 3048 times)

martijn76 · « **on:** October 18, 2009, 06:56:48 AM »

My e30 318IS has a problem wich I cannot seem to solve..
When going up in rpm fast, around 38/4000 the engine starts to stutter and above 4200 drive normal again. Sometimes also a bit when starting to drive when the engine is hot.
When gaining speed more carefully, there's no problem; maybe a small 'hump'.
Overall the engine is great, no valve noises other than normal, no rattling etc.

Things I replaced for new parts since the problem started, or when I swapped the engine:
-all the air hoses
-airfilter
-petrolpump
-petrolfilter
-air mass meter
-gasvalve position sensor
-idle valve
-DME chip
-sparkplugs
-sparkplug wires

I don't have any more ideas, I thought about changing the Lambda, but when that failes it should give another problem. Same with the coolent temp sensor.
Anyone?

DesktopDave · « **Reply #1 on:** October 18, 2009, 10:21:02 AM »

Check the cam sensor resistance, should be 'round 1200 ohms. It's been known to cause spark timing problems at higher revs like yours.

martijn76 · « **Reply #2 on:** October 21, 2009, 05:23:28 AM »

When the cam sensor fails, should't that give problems from 4000 revs and higher, instead of only at 4000 and past 4100 all is good again.. It's a frustrating problem

RED IS 91 · « **Reply #3 on:** October 21, 2009, 07:32:16 AM »

I had a similar issue and it ended up being a bad coil .
good luck

martijn76 · « **Reply #4 on:** October 25, 2009, 10:26:08 AM »

Problem solved:)
I already swapped the coils for another set, that set gave more problems so I thought mine were fine.. I took a better look at the sparkplugs and noticed just a bit of cokes on two out of four electrodes, so I took my changes and bought a new coil for cilinder no 4; that did the trick..
I didn't expect a coil to be the cause of this problem, since it was only between 4000-4200 revs.
I'm gonna change the other three too, if one goes bad the rest will follow in a short amound of time, I just wanna be safe.

dj91318is · « **Reply #5 on:** October 25, 2009, 11:35:33 AM »

It could have just been a bad connection. All electronics can fail even new ones. It seems odd that a coil can fail only at certain impulse intervals.GL

martijn76 · « **Reply #6 on:** October 26, 2009, 09:42:06 AM »

Because the failure was only a small range I didn't suspect the coils, after I discovered this I called the BMW dealer and they confirmed that that sometimes hapens..