Hight Idle 1800-1900 rpm?? whats wrong?

[Brinkland]

My Bmw is 1800-1900 RPM at idle if you just take a drive drops the sometimes down at 1200 rpm and otherwise increase it again ....
Have read a bit around the web that idle regulator could be the fault

I had removed the idle regulator, cleaned it and blasted it through with a little compressed air.
Have checked almost all the hoses in the engine compartment if there are cracks or the like which can give false air
there is a small crack on the rubber air intake boot, but to exclude it, I used some liquid gasket, but it is still extremely high idle.

Is it my idle regulator has passed with 100% certainty? some who have other experiences, and it may be something else?

So it must have a new rubber air intake boot , and so something else must change course to solve the problem

It is a Bmw e30 320i from 87, (25/08/87)



hope you can help


Pictures:

[Grrrmachine]

By having an August 87 model 320i, you have the very last of the Jetronic systems, so your "idle regulator" (Air Slide Valve) isn't like the later Motronic Idle Control Valve. You've also got a really complicated network of vacuum hoses which were simplified on later cars.

Still, have a read of our Wiki on this issue:

http://www.e30zone.net/e30zonewiki/inde ... ake#Idling

and this:

http://www.e30zone.net/e30zonewiki/inde ... lide_Valve

It gives you a few points to work though, such as the Blue Temp Sensor which is normally the cause of high idle. Air leaks normally cause low idle, not high.

[Brinkland]

By having an August 87 model 320i, you have the very last of the Jetronic systems, so your "idle regulator" (Air Slide Valve) isn't like the later Motronic Idle Control Valve. You've also got a really complicated network of vacuum hoses which were simplified on later cars.

Still, have a read of our Wiki on this issue:

http://www.e30zone.net/e30zonewiki/inde ... ake#Idling

and this:

http://www.e30zone.net/e30zonewiki/inde ... lide_Valve

It gives you a few points to work though, such as the Blue Temp Sensor which is normally the cause of high idle. Air leaks normally cause low idle, not high.

Thanks alot
Should I buy the blue temperature sensor, it may solve the problem?
can I see if it works? for example. if the engine is turned on and I take the plug of the sensor?

[pacerpete]

The blue temp sensor will not solve your problem though it may well be toast. The details of how to test it are readily available.
You need to verify that the 'air slide' is functioning correctly, the easiest way to check this is by clamping the long hose that comes across the inlet manifold to the idle bypass screw housing WHEN THE ENGINE IS HOT. If the revs drop when you clamp the pipe, the valve is u/s and needs replacing, they are not serviceable.

Distributor advance weights can stick but unlikely . It is worth checking your ignition timing as it is seldom set correctly and you will be losing valuable MPG and BHP

[Speedtouch]

+1 on the water-heated air-slide valve probably being the culprit. I had a 1987 320iSE with the same problem.

[Grrrmachine]

Info in this thread has been Wikified.

[Brinkland]

Hi guys


If I push the vacuum hose together so falls the rpm's, depending on how hard I press (I can control it by how hard I press, for example. down to 500 rpm or 800 etc)
... the hose goes to a T-piece and down to the air slide valve (idle controller) - Is it the air slide valve does not work?? or ?

[Brinkland]

I've had dismounted idle regulator( air slide valve) again and had it in a pot with 70-90 degrees c water

Have taken pictures of before and after. It works as it should? or close it not as it should?

Subsequently, I have adjusted the idle screw.
If I screw the idle screw all the way in, and then only a turn out so I can get it to stand at about 900 rpm when the engine is hot
Is it wrong to idle screw should only be turned one half turn out to be 900 rpm at idle?

- Or is it still my idle regulator( air slide valve) is the problem? Closes as expected?

Now, the cold


Now it has been in the 70-90 degrees hot water for 5-10 min

[Speedtouch]

Although it's clearly working, surely it should fully close?

[johnl320]

Hi guys


If I push the vacuum hose together so falls the rpm's, depending on how hard I press (I can control it by how hard I press, for example. down to 500 rpm or 800 etc)
... the hose goes to a T-piece and down to the air slide valve (idle controller) - Is it the air slide valve does not work?? or ?

Isn't the anti stall actually pushing the throttle lever open in the top pic?

[Brinkland]

Hi guys


If I push the vacuum hose together so falls the rpm's, depending on how hard I press (I can control it by how hard I press, for example. down to 500 rpm or 800 etc)
... the hose goes to a T-piece and down to the air slide valve (idle controller) - Is it the air slide valve does not work?? or ?

Isn't the anti stall actually pushing the throttle lever open in the top pic?

yes it is true, but it does only when the engine is off

[Brinkland]

Although it's clearly working, surely it should fully close?

yes, it can not close more than the picture, you may not close enough?

and then maybe why I should turn the idle screw all the way in, to compensate for the

[Brinkland]

It does not close fully.

Ok, thanks

Thanks to all !

I want to buy a new one, and so I write again in this topic, and I hope it will get to run better at idle

[Brinkland]

can tell it was not my air slide valve ..

Should the same day change timing belt / water pump etc.
There should of course I put the three pulley off the timing marks, and after it is changed and assembled so that it runs idle at 700-900 rpm, depending on the adjustment

so my mechanic says one of the pulleys has not stood correctly off the timing marks, so it might have made spark too early?

Anyone who has tried it before?

[Speedtouch]

Fitting the timing belt one tooth out would almost certainly affect the idle speed.

I took my first E30 320i, an L-Jet model, to a branch of Halfords to get the timing belt changed, and they must have fitted it one tooth out because the car never ran right after that - it struggled to rev over 4,000 rpm, whereas previously, it would rev cleanly to the red line.

So yes, I would check that you have fitted the belt correctly.