Oil Change/Idle! ?

[Shark]

Hi Guys/Girls

This is weird!, I did an oil and filter change on my wifes 1990 316i Lux today.

The cars idle has now risen to about 1200 rpm, before doing the oil change it was OK at 900 rpm.

The brakes at the front have also now lost their bite and the pedal is spongy and you have to use a lot of force on the pedal to get any braking.

OK, any ideas anyone.

Thanks

Neil.

[Andy_magic]

Welcome Neil.

I reckon you've knocked the vacuum hose off that goes between the brake servo and throttle body. This would have 2 symptoms.

No power assistance for the brakes and too much un-metered air getting into the motor, casusing a high idle speed. It will probably be a sod to start when its cold too.

Remedy - check the servo vacuum lines really carefully, although I suspect you could probably hear the air leak fairly easily.

Good luck and post on how you get on.

Could also be a broken one way valve somewhere on the servo hose...

[Shark]

Cheers Andy_magic.

It gets more interesting, before I read your reply I cleaned the ICV, TB and AFM, it was then in 2 minds, worked OK and then didn't. Now it seems to be working OK with only one tantrum since.

[Andy_magic]

Cleaning all those parts will only do good, how are the brakes?

Check the brake fluid level and watch for smoke as if the master cylinder has gone it might draw brake fluid into the inlet manifold.

Not only is this bad for the brakes but could reck the CAT if fitted.

[Shark]

I don't know now, when the car is now warm it will hold on to the revs when coming to a halt and idle at about 1200 in Drive and 1800 when moved to Park. After a while at standstill in Park the Revs will drop to a normal 750 to 900 rpm.

I have run the car without the electronics plug connected to the ICV and it still does the same, don't know really what to conclude from this.

I have sprayed Carb cleaner everywhere with no results.

The AFM, ICV, Thermo Switch, Main relay(DME) and Fuel Pump relay are just a year old, can't see it is one of these.

Any ideas any one?

Cheers Neil.

[Andy_magic]

No mention on the brakes still, they must be working fine now.

Sticky throttle cable, kick down cable binding. Is there a throttle damper fitted.

DO YOUR BRAKES WORK OK - LOL

[Shark]

Hi Andy-magic

Yes brakes working OK now, just this idle problem.

[Andy_magic]

I had visions of you driving about with dodgy brakes.

If you have a spare ICV stick it on and plug the one currently fitted in and watch if it moves with the engine running.

have you carried out the usual tests on the ICV

[Shark]

Andy_magic

This is my BM

http://www.e28club.com/gallery/car.asp?id=76

The E30 is mine but I let the wife use it for work and shopping

What are the usual ICV test?.

Neil.

[Andy_magic]

I like that!

I'm not sure of the exact figures for the ICV fitted to your car, but I reckon they should be the same as a 6 pot??

If you get a multimeter, set it to reisistance mode and put a probe on the centre contact of the ICV you should see 20ohms on both outer terminals. If you get a reading much different to this then it points to a winding open curcuit or shorting out. The are usually ok.

The next test is a little less scientific in its approach.

Get hold of the ICV by the black part with the connector facing the floor and the hose connections facing up, then rapidly spin it back and forth. What your aiming to do (apart from look silly) is to see if the valves internals rotate freely. My guess though is that it's fine.

I think I read somewhere about dip stick oil seals, again I don't know if these are on the 4 pot motors, but worth a look. I guess a way to check this would be to remove the dipstick, start the engine and put a thumb over the dipstick hole to rule out any air leaks there.

All my expreinces are on the 6 pot motors but most of it shoud translate in some way to 4s

[Shark]

Cheers Andy_magic

Will have a look at what you have suggested.

[Shark]

Well check everything and it just seems to have gone away. I think it is the ICV which is now and again throwing a wobbly, so I have a another one on the way.

Cheer for you help Andy_magic.

Oh! by the way does anyone have an idea what this is.

The car also has a whirring metalic low pitch sound which does not diappear under acceleration or braking. I have renewed the diff oil and added some moly slip, noise is still there though.

Has anyone had this one?

[Andy_magic]

Glad to hear the cars sorted.

Does the noise vary with road speed or engine speed??

Does it change when cornering hard.

If its road speed I would look at the wheel bearings.

Both rears are shot on my car and it sound like you being followed by a WW2 Lancaster bomber at motorway speeds

[Shark]

Hi Andy_magic

No have not checked the wheel bearings, will check them now. The reason I did not check them before now is that it has just been mot'd so I thought they would have picked up on knackered bearings.

[Shark]

Forgot, yes noise does increase and decrease with speed, I mean it is not loud,here is another analogy, it souds like a low Humming metallic noise it does not sound like a lancastor following me.

This will show you how loud it is, if I ask my wife can she hear it she says she cannot, but thats more to do with not being in tune with the different noises cars make when something is up.

[Andy_magic]

I see where your coming form, mine a well knackered and make a fair racket but there isn't MOT failure worthy play in them.

I'll be doing mine in the next couple of months as the test is due in august. MMMM can't wait

[Andy_magic]

It could be the diff, it's really hard to say without listening to it.

[Shark]

Andy_magic

It has just struck me, are you the only member of this forum?

[HotboxDeluxe]

No, there's me too...

[Shark]

Hello

Your on the E28 forum (invision) as well?, or have I got it wrong

[HotboxDeluxe]

That's me, but I'm no traitor, honest