Aircon idle speed not working

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jermyns
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Wed Dec 26, 2012 4:29 am

One for Brian I think.

1986 325i.

3 pin flat plug on wiring harness plugged in, but it is still not idling up when aircon compressor switches in.

What should i see on the flat plug and on what wire?
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Billwill
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Wed Dec 26, 2012 8:18 am

Definitely one for Brian.

I do not know the early 325i but I would assume that you would need to see +12 volts on one of the wires when the compressor kicks in. :?
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jermyns
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Thu Dec 27, 2012 2:07 am

Hi Will,

OK, I will look for the control unit, what does it look like and does it have a plug going into it??

Regards,
Steve
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jermyns
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Thu Dec 27, 2012 8:34 am

OK, I will look tomorrow.
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jermyns
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Fri Dec 28, 2012 11:47 pm

Will,
The ECU is Bosch 0261 200 027, the next number series are; 1 708 643.9

Regards,
Steve
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jermyns
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Sat Dec 29, 2012 5:05 am

Definately (was) a 325e in the beginning, but the engine has seen the Alpina mods, so a big difference in performance. Sorry about the bum steer.

The ecu is the original one the car was born with, so let me know what to check and I will have a look.

Steve
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jermyns
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Sat Dec 29, 2012 9:24 am

Lots of mods. 325i Head, ported and polished, 325i cam, pistons, blah, blah, blah.

Intake manifold is the 325i, but still has the 7th injector for cold start and the idle control is original.

The ECU has been chipped on a rolling road, so not sure exactly what it is. I cannot see any box sitting on top of the ECU, just the alarm/immobiliser.

Steve
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Sat Dec 29, 2012 12:45 pm

Thinking aloud, are you just trying to trigger the higher idle, or, are you turning the aircon on and the idle is not raising? i.e. could the load of the aircon compressor be dragging the supposedly raised idle down to the original level?
I said:

Can anyone suggest how to test if the boot lights are staying on with the boot shut?

e30topless said:

lock the wife in there
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jermyns
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Sun Dec 30, 2012 8:01 am

Hi Will,

A great combination, 325i running gear and the 327 stroke. Beautiful tourque curve that allows you to pull away in 5th from 1200rmp if you choose to do so.

I have 3 BM's including a e36 coupe (red of course) and a e46 330ci CAB, but my favourite by far is the E30.

Yes, already attended to the TPS setting as the car had been mothballed for a few years and was definately not running well at first, but after replacing the TPS and adjusting as per the wiki it idles perfectly unless the aircon is switched on.

The aircon had been out of action for probably the last 8 to 10 years, but I do remember it did idle up when the AC was switched on.

The ICV is the 2 pin type. I think the later 325i has a 3 pin type, so not the one in mine.

I have a full workshop manual (with my son at the moment) so will not be too difficult to find out where the ICV goes to in the ECU, if that's where it ends up.

I will post again when I get my manual back!!!

Steve
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Sun Dec 30, 2012 11:39 am

jermyns wrote:The aircon had been out of action for probably the last 8 to 10 years
Realistically you need to get the belt off and check the pump turns smoothly by hand before fussing over the elecrics. HTH
I said:

Can anyone suggest how to test if the boot lights are staying on with the boot shut?

e30topless said:

lock the wife in there
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jermyns
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Sun Dec 30, 2012 8:34 pm

HTH,

Aircon works fine, new compressor, receiver/dryer and gas....loads of cold air coming out, but loads up the engine because the idle-up is not being triggered.

I own a auto mechanical business, so will be simple to fix when I know what to look for, hence the questions to Will and Brian who have the deserved reputations of knowing this stuff inside out.

Happy to have input because that how we all learn :P

Steve
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Brianmoooore
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Sun Dec 30, 2012 9:02 pm

Is the idle speed control working at all? Or has it been set up on the throttle stop, like an older/more primitive car with no feedback loop?
Does the idle hold steady if you turn every electrical load on?
Does it hold speed if you drive along in second gear with your foot of of the throttle and come to a slight incline?
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jermyns
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Sun Dec 30, 2012 11:07 pm

Brian, yes the ICV is set up to work and will maintain idle speed when all electricals are turned on. Haven't tried the 2nd gear test but I will.

Will. OK, looks like I have to do the testing the hard way but it will not be very soon.

We are 2 hours south of Sydney and it continually amazes me how many people will leave to go on holidays without either servicing their car, or worse leaving with a known problem only to break down around my location :mad: Flat out at the moment, so no working on my toys :(

Steve
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jermyns
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Mon Dec 31, 2012 10:35 pm

Excellent advice, will pass on the suggestion immediately!
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