This could get rid of your rough lumpy idle!!!!

[e34.535i.sport]

Hey fellow e34 nutters... Have you got a rough idle? I tried SO many things to get rid of mine using the wealth of information on this forum and recieved a LOT of help... I put up with it for a long time (months), but only today I fixed it completely! There are so many things that can cause idle issues it is always going to be a bitch, but I found this useful: http://www.bimmer.info/forum/showthr...e+shimmy+guide Kudo's to Shogun for that little gem.

You probably saw my thread recently about my rough idle and low mpg...
If not then here it is: http://www.bimmer.info/forum/showthread.php?t=38031

I guessed it was the ignition or 'HT' leads and I was half right... It turned out the idle and high fuel consumption was due to something called a PULSE GENERATOR that comes off the ignition wires. Well worth a check if you can't solve your rough idle problem. Here's my second thread whining about putting it on:
http://www.bimmer.info/forum/showthread.php?t=38152

This may also be of use:
http://www.realoem.com/bmw/showparts...49&hg=12&fg=05

I just thought I'd throw this on under this title incase anyone does a search in future... Its a cheap and relatively easy fix for a really annoying problem! Hopefully someone will find this useful in the future!

[e34.535i.sport]

Hey bad news... The idle seems too have returned to 'normal'... Maybe I jinxed it.

Like most things in life- if it seems to good to be true it normally is.

It's annoying because it was really smooth all day yesterday and I drove it to a few places throughout the day. Today I get in and it's totally reverted. I WILL find out what it is... This car is testing me.

[Tiger]

I can't read through all those threads... can you compile what you have done already?

[Julien]

BAM

[e34.535i.sport]

[QUOTE=Tiger]I can't read through all those threads... can you compile what you have done already? [QUOTE]

LOL! Don't blame you! I was only posting this to help people who search in future as a quick fix... but it's returned to normal. Boo.

Anyway to improve the idle I have:

*Checked all vacuum hoses and gaskets on intake and throttle body for leaks.

*Checked HT (ignition) leads, all look good including boots

*Replaced pulse generator (had totally broken off)

*Replaced Spark Plugs

*Removed and cleaned Idle Control Valve

*Changed Fuel Filter

*Cleaned throttle body connection for idle...

*Also I have removed the oil dipstick with car running to check for intake leak - the idle changed significantly so i'm certain its not related to a vacuum leak problem.

I am going to...

1. Check and clean Crank Position Sensor
2. Remove and clean/change Injectors
3. Replace Fuel Pressure regulator
4. Do a Valve Adjustment
5. Go


The list is in order of what I think could be the problem. It never used to bother me the rough idle but now I now how good the car can feel I want it all the time.

I had a while of trouble free driving there now the car's decided to pull a sicky on me. Why does it all have to happen at once?!

[Tiger]

I would suspect crank position sensor. Just replace that thing with the one from dealer. Even Bruno had a hard time figuring what is wrong with a customer's M20... and it was crank position sensor...

[e34.535i.sport]

I would suspect crank position sensor. Just replace that thing with the one from dealer. Even Bruno had a hard time figuring what is wrong with a customer's M20... and it was crank position sensor...

Hey thanks Tiger, your giving me hope... Will order it tomorrow, hopefully it wont cost a fortune like the dealer pulse generator!

[e34.535i.sport]

Hmmmm... I have no valve adjustments on record so I don't know when they were last done (if ever!). I really would like to do this but the job worries me. I've had a new valve cover gasket and nuts in the boot for months too...

With the car running so perfectly for a while after the new chip went in and the pulse generator it made me think it won't be the valve clearances causing the issue but I don't know.

I might do it at the weekend if the weather's good and I don't bottle out again. I've read up on the job a lot but I still don't understand w-t-f to do. I'm asuming it makes sense when you can see in there!

[e34.535i.sport]

Have you tested all the HT wires, cap, rotor and plugs? Injectors clean? No vacuum leaks? Gotta' have a good basic tune up before trying to diagnose small driveability problems.
It is very sensitive to valve adjustment, they will idle better at the loose end of the range but be noisier.

I posted some of what I've done in response to tigers thread, but I also used fuel injector cleaner which didn't do anything really.

Plugs are new, cap and rotor look fine and HT leads look ok too from a visual inspection... All that stuff seems fairly new actually. Also, i'm definite its not vacuum leak.

[Robin-535im]

Hey thanks Tiger, your giving me hope... Will order it tomorrow, hopefully it wont cost a fortune like the dealer pulse generator!

When was the last valve adjustment done? That can make the idle lumpy if they are out of whack. 0.013 inch gap cold, IIRC - check Bruno's site.