Help with idle

[Tineca]

Hi the car is new to me and been off the road a while. It won't come down from 1200 revs even when warm. I removed the throttle body and the air flow metre from the car and cleaned with carb cleaner. They were a bit oily. No obvious air leaks. Sprayed the manifold and pipes with carb cleaner but no rise I revs. Checked the water slide valve, that works. Had it in a jug of hot water and you can see it working. Any ideas? Thanks Jed

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[flybynite]

Welcome to the world of the LE Jetronic

The first thing I would suggest is REALLY check for vacuum leaks, Lost track of the happy hours chasing vac leaks on my 323.

You need to check everything.

Did you spray the 'start ya b#$7@rd' around all the likely areas like brake booster, breather etc. I generally use Bradex as i find carb cleaners these days a bit eco friendly for the job.

A crack in perished rubber would be my top bet, You won't see it

What happens to the idle when you take off the oil filler cap?

!!!!! mind the fan !!!!! what happens when you pull the tube of the distributor advance?

Happy hunting

This is why mine is going Motronic 1.3

[Tineca]

When I take the oil filler cap off it drops right down, almost sucking in, no back pressure. I just removed some sort of valve from the pipe to the dizzy and it reduced the idle but smooth. There is a lot of white steam exhaust and it smells like it's on choke. Put me out of my misery please

[Brianmoooore]

The first thing I would suggest is REALLY check for vacuum leaks, Lost track of the happy hours chasing vac leaks on my 323.

I'd say the first thing to check is that it's not something so simple as the throttle butterfly not being to far open, either because someone has been adjusting things that shouldn't be adjusted, or even an over tight throttle cable.

This is why mine is going Motronic 1.3

Can't argue with that!

[Tineca]

Will have another look tomorrow. Thanks for your help

[Brianmoooore]

We've just concluded another "high idle" thread on here, which ran to many posts. It turned out that the idle wasn't high at all, but the OP thought it was because of a misreading tacho.
If your car has had the tacho. replaced at some time by one from a four cylinder car (or rather the coding chip), it will read 1200 RPM when the actual revs are about right at 800 RPM.

[Tineca]

It's definitely high the fan is whizzing at a right rate of knots.

[Brianmoooore]

If the viscous fan coupling is locked, either because it should be, or is seized, the fan will make a considerable roar, even at idle. Don't forget a four cylinder engine at 1200 RPM sounds like a six cylinder at 800 RPM, in terms of bangs per second.

[Tineca]

Mines a six cylinder and it is revving high Also the temp guage is not reading, that won't be causing it would it? If I take the oil cap off it wants to stall.

[flybynite]

Firstly I should have said go through some of the old threads, mine of information. Look for posts from BrianMoooooore above

If the oil cap is dropping the revs then it is not a general leak.

As Brian says above check the TB closes properly.

Then it is a case of taking each of the rats nest of small vac pipes off all the jetronic valves and wotsits (which having owned mine for over 30 years I still can't name what each does) and see if any make a difference.

AFAIK The Jetronic still has separate plugs for ECU and Gauge, doesn't mean both are not knackered .

[Brianmoooore]

Taking the oil cap off should make it want to stall. That's part of what me suspect that there might not be anything wrong, other than the tacho.
Temp. gauge is nothing to do with this problem, but take the plug off of the sensor and use a piece of wire to earth the single pin in the plug to the engine or body. Temp gauge should go to full hot with the ignition on.

[Tineca]

Ahh thanks that helps. At least I know it's prob not an air leak. It sounds like it's on choke if you know what I mean. Sorry to ask again but if that sensor isn't working does the car not think it's still cold and mess with the fuelling. I will try that pin trick

[Brianmoooore]

The temp. sensor in question is just for the temp. gauge. Combined sensors weren't used until the E36.
What's the age of your 323i? There were changes during the production run.

[Tineca]

Mines the 2 sensor version brown and blue 1986. I have just ordered a set. Seems a fair punt for £30

[Brianmoooore]

Don't change things on spec! Test first.
Cheap replacement blue sensors can cause more problems than they solve. They might be correct at full cold and full hot, but might not 'track' correctly in between.
Got a £1000 E30 for £200 once. Previous mechanics had tried and failed to sort the drivability problem, and had replaced the blue sensor with a brand new one as part of their attempts. One second hand genuine sensor later, I had a fully working bargain that served as my daily driver along side my 'family' 325i touring for many years.

[Tineca]

Thanks Brian so how do I test the sensor that controls the fuelling? Is there a way? Thanks jed

[Brianmoooore]

The blue sensor is inherently much more unreliable than the brown one, and is most likely to fail high resistance or open circuit, telling the electronics that the engine is much colder than it is.
You can test it at its working extremes by measuring its resistance cold, running the engine to full temperature, then measuring again. These measurements are preferably taken at the ECU plug, so that the results include the wiring and avoid disturbing the actual sensor.
For a comprehensive test, you'd have to remove the sensor and gradually heat it in a bath with an accurate thermometer, while monitoring the resistance, then comparing the resulting graph with the manufacturer's data sheet.
Your problems as described are not what I'd expect from a faulty blue sensor. Either the engine would be extremely difficult to start and keep running until hot, or more usually, would start and idle absolutely fine, but become progressively rough as the engine warms, and probably eventually stall.

[Tineca]

Thanks Brian gonna have another look after work tonight.

[flybynite]

The other culprit in the 323i can be this little gem:

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What happens when you pull the pipe off?

It may also be holding the throttle open, so what happens when you unbolt it ? (leave the pipe plugged in)

Just because the revs drop, does not rule out a vacuum leak on one of the smaller pipes, or a vacuum blockage can cause issues too.

[Tineca]

What's that part called? Some sort of diaphragm?

[flybynite]

What's that part called? Some sort of diaphragm?

Officially 13541289039 'control box'

it is the idle control, anti-stall.

[Tineca]

Thanks for all your help.

[Tineca]

In my dinner break I just fired her up and squirted some more carb cleaner, no change. I walked round to the opposite side near the expansion tank etc and squirtted around those small pipes and it revved up. Looks like it's a leak in that vicinity. Encouraging news eh?

[Tineca]

Hi folks. So first job was to go against Brian's advice and try a new blue temp sensor. Did it fix it? Did it heck in fact it ran awful and nearly didn't start. Sorry Brian, I am satin corner with D cap on and no tea. . Also I was wounded as a new brown sensor failed to make the temp guage work. I tried putting the wire to earth and the guage didn't move. It moves about 2mm when you turn the key on. Any ideas??

Back to idle and I found a vacuum leak. Yay I thought. Did a bit of a moon walk. Where was it then? I hear you ask. The smooth side of that giant inlet sculpture has on the same side as the water tank has a little plate type thing with hoses and stuff attached. The 5 bolts were loose. Did that fix the idle? Nope

So back to that silly thing as pic that fits in line between the dizzy vacuum advance and the aforementioned sculpture.
With this fitted it idles at 1500. With it removed it sits at 900. It's obviously letting in air. Should I just not fit it? With it not in the idle isn't super smooth. Or should I try and blow 60 quid and see if it helps? Also my dizzy has two vacuum pipes. You can actually detach one and no difference is made. My exhaust fumes are white and steamy even when warm. Is that normal? Fan runs constantly too. Any help appreciated. Thanks Jed

[flybynite]

Have you looked at the thing I circled above? Unplugged the pipe and then disconnected it?

Oh and invest in a 323i Haynes manual (bit confusing as it has an E21 on the cover) It is one of the better sources of info on the 323i which was not sold in the USA so we are devoid of their 'wisdom' on these wonderful Jetronic engines

[Tineca]

Hi yes I have the Haynes when I pull that blue pipe off in the circled bit it revs up fast. I have a vid on of it tickover but can't seem upload it

[flybynite]

If it revs when you take the pipe off, then it is working and not stuck. What you need to do is check it can go lower. Either push it back or dismount it (leaving the blue pipe connected) see what it does.

As Brian says, don't replace things unless you are reasonably certain. I have my doubts that valve is available from BMW (KOED Denmark or Krasta Vilnius included) as it is listed as NLA. That is why I was looking for a link to the Pierburg aftermarket.

Have a search back through the forum for thoughts on the viscous fan.

Your distributor advance has 2 pipes because it takes the vacuum from both sides of the throttle butterfly, the ignition advance is the difference between the two and most evident as you open the throttle from closed. Disconnecting pipes at idle proves very little.

[Tineca]

OK, just checked the butterfly is free and can close. The idle without that valve thing is quite normal apart from a little bit of fluctuation. I have just used a second can of carb cleaner and no leaks. I got the pipe off that goes under the manifold as that has a tiny tee off. A tiny bit of mayonnaise was in there. Cleaned up and replaced. Still no vacuum leak. It appears now I have spent a couple of days checking each and every pipe there are no more leaks. I might try and buy that valve to see if that smooths it. Mike found one in Denmark. https://www.ebay.com/itm/BMW-Ventil-117 ... ect=mobile.

[Tineca]

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Getting there.