Standard Idle - UPDATE

Post Tue May 30, 2006 11:24 pm

What should a 89 325iSE idle at?, when static I'm chugging on 400 - 500 and in danger of stalling....just changed ECU's last week so don't know if I need to take her for a run to relearn settings after having a wild chip in the old ECU?

Cheers

Post Tue May 30, 2006 11:31 pm

most cars idle between 600-800 rpm so thats a bit low, theres an idle adjuster screw on your throttle body, that mite need adjusting

Post Tue May 30, 2006 11:33 pm

just read your post properly has it only been idling low since your new ecu,s been fitted?

Post Tue May 30, 2006 11:36 pm

DelaneyG wrote:most cars idle between 600-800 rpm so thats a bit low, theres an idle adjuster screw on your throttle body, that mite need adjusting

Do not adjust that screw! it's for the idle CO levels nowt to do with the idle speed.

The idle speed is set by the ECU chip

Post Tue May 30, 2006 11:37 pm

how does it affect the co level

Post Tue May 30, 2006 11:41 pm

DelaneyG wrote:how does it affect the co level

EHH? turn it one way and the mixture gets richer, turn it the other way and it gets leaner........ don't play with it !

Post Tue May 30, 2006 11:42 pm

No, your talking about the screw on the airflow meter
I'm talking about the throttle body

Post Tue May 30, 2006 11:45 pm

DelaneyG wrote:No, your talking about the screw on the airflow meter
I'm talking about the throttle body

oh yeah! oops

I don't think your supposed to use that screw to adjust the idle speed, but then why is it there otherwise?????

Post Tue May 30, 2006 11:47 pm

you shouldnt have to but he's got a problem so it's woth trying cos it mite work

Post Tue May 30, 2006 11:51 pm

Razza

was the car tuned by the person who fitted thd chip?

if you do decide to adjust it yourself only turn the screw about a quater of a turn at a time an let it settle for a minuet cos its easy to mess it up

Post Wed May 31, 2006 12:01 am

DON'T TOUCH THE SCREW!
Check the throttle position switch is working properly.

Post Thu Jun 01, 2006 7:11 pm

Going to need to get this checked out

Idling at 500, running fine in high gears but traffic is a nightmare and feels like she's gonna stall.

Just got home and opened the bonnet and theres a clunking coming from somewhere when idling - pre new ECU she'd never run better

I had to get a new ECU cos my mechanic said the last one was spiked after I botched zone chip fitment although it ran great for about 3 months, not sure I beleive him

What would a low idle indicate generally?

I'm very rapidly falling out of love with E30's

Post Thu Jun 01, 2006 7:50 pm

I expect it would clunk at 500RPM.
Idle speed is controlled directly by the ECU operating the idle control valve, which it will only do if the TPS tells it the throttle is closed.
Do you have the right ECU? What are the numbers on it, and what is your engine?
Not a solution to your problem, but there's an unused socket or two on a bracket right next to your ECU. One of the pins (black/red wire, I think) is connected to 12V + when aircon cuts in, to increase the idle speed. Be an interesting experiment to see what applying power to this pin does on your car.
Not at all sure of which pin, so don't try it untill someone else has confirmed it.

Post Thu Jun 01, 2006 9:08 pm

Brianmooooore

I have a G reg 1989 325i SE

My original and previously perfect ECU has the following numbers:

On the left side

1726102 001
810

On the right

0 261 200 173

The new ECU has the same number on the right but the left reads:

1722269 001
078

I don't really know the significance of this other than the 173 refers to my car. Might I have a pre-face lift or simply duff ECU?

You seem to know your onions so I'd appreciate any input

Cheers

Post Thu Jun 01, 2006 9:34 pm

Don't know about the ECU, could be the wrong one indeed. If that's okay:

- don't touch the screw
- check the TPS
- check/clean the ICV
- get the CO (idle mixture) checked and adjusted at an MOT station
- don't touch the screw

The clunking is probably a side effect from the lousy idle. Perhaps gearbox rattle, wouldn't worry too much about that.

Post Thu Jun 01, 2006 9:55 pm

That's the correct ECU for a 88-90 M20B25 running Motronic 1.3.
Have you checked the TPS yet?

Post Thu Jun 01, 2006 10:37 pm

Sorry I'm a novice

How would I check the TPS, where is it and what should I look for?

Or, should I get my MOT tester mate to have a look at the weekend?

Post Thu Jun 01, 2006 11:08 pm

TPS (throttle position sensor on modern cars, but throttle position switch on E30s) is underneath the throttle body, operated by an extension of the throttle butterfly spindle.
It should make a faint click just as you move the throttle of its stop, and another one at about 2/3 throttle.
If it passes this test, take out the air filter/AFM assembly and remove the big convoluted hose from the AFM to the throttle body. (Check it for splits and cracks while its off).
You will now be able to see the TPS. Remove its plug, and connect a resistance meter to pins 1 and 2. You should get a short circuit ( 0 Ohms) with the throttle closed, going open circuit with the throttle just off its stop.
Pins 1 and 3 should be open circuit until the throttle is 2/3 open, when it should go short circuit.