Idle problem when cold and sometimes when hot

[ProToZyKo]

I have a little problem with my bmw E30 320I 1987, when i start it in the morning and after work it almost dies when idling, it goes up and down on the rpm, when i give it a little gass it get's better, but if i lift the foot off the throttle it almost dies, sometimes it does.
Sometimes after a 15 min drive when iam about to park it will do the same.

I tried to adjust the idle and i got it to stay at a normal rpm, but it was hot then, but if i adjust it higher my car will idle at 1500+

Also when i changed the tube that goes from AFM to throttle body i noticed that my gasoline usage pr mile is at 0,2 when driving with no gass, it used to be under 0.
I got the idle problem around 2 weeks after replacing the tube.

I can't see anything wrong so im hoping you guys can guide me.

[Brianmoooore]

There is no idle adjustment on an E30!!!!Before you can do anything to find out what is wrong with it, you need to put the adjustment you have been turning back where it was. I hope you counted the turns, because it needs a special device to set it up properly!
Adjusting the 'idle' screw will cause the econometer problem.

[ProToZyKo]

oh no, I think i adjusted it 1 turn, but not quite shure ;(

[ProToZyKo]

I adjustet a screw on the throttle, the screw only pushed the throttle forward and holds it, same if i hold the gass.

[ProToZyKo]

Any suggestions? Getting tired of holding the gas when starting up the car. Sounds like crap also when cold, up and down with rpm

[Brianmoooore]

What engine management system does this car have? Are there sensors mounted on the bell housing?

[Bobbydoughnut]

AS BM says, the system is cleverly balanced by the ECU and AFM and needs specialist set up, adjusting the screw only opens the throttle, needs set back, it doesn't source why you've bad idling, that's down to bad airflow control or bad cold start info to the ECU from the AFM/TS - check ECU wiring from the AFM just in case you disturbed that changing the main induction pipe and that every feed pipe from that is tight.
Check the Idle Cotrol Valve/speed control actuator (ICV) for correct operation, cleanliness and feed pipes - they can get gummed up, also the Temp Sensor (TS) for continuity.

[MrDazzle]

I have a similar problem on me iS...

It used to hunt at idle, so I replaced the ICV. Not it holds 750rpm but 'chugs' at idle and sometimes dies at random when stationary like ProToZyKo describes. It used to be chipped but I've switched it back to the standard ECU.

It only started doing this when I changed the engine. I've got the original manifold TB and ECU etc., but a new lump. Could that be where the problem started?

Do BMW dealers have the kit to reset the throttle properly? Will that help?

[mick_318is]

I had almost the exact problem with my 89 320.

I found that the TPS was full of oil.

I took off the TPS and gave it a good clean with carb cleaner.

Problem solved.

[Bobbydoughnut]

Did you swap the sensors out too MrD? Snds like you've got a duff sensor as Mick suggests if you are using everything else from the old lump

[MrDazzle]

Tried swapping the blue temp sensor from the new engine with the old one (dunno if either work TBH!). The new ICV is deffo better than the old one (the new one came from a third engine). The speed is right, it just idles really roughly and sometimes stalls as you pull off.

All the 'engine mounted' sensors (eg. crank speed etc.) came with the new lump, the manifold mounted ones (e.g. TPS, AFM etc.) are the originals.

[78dude]

Take off the air flow meter and look if some one have tryed to fix it before. (you will see that on the black square thing on it who have the same size as an old music tape cover circa, it will then be fited with glue after the repair)
Try to get another one like borrow one from some one here who have the same car and see if that is your main problem to this issue? Its not unormal that they give up after 20 years of use

[Bobbydoughnut]

does it only do it when it's cold, is it fine when warm? There is a really neat trick when it comes to the E30 AFM whereby you can move the internal arm and contacts to a clean part of the ceramic track and up the feed to ensure a stronger V signal but this usually manifests itself as a lumpy pick up, the AFM doesn't really come into play at cold idle, you can check the AFM by a meter on the pins of the AFM and check that the resistance rises steadily as you open the flap inside.
This is for a 88 Porshe AFM but the E30 is almost exactly the same - Ive reconn'd 6 back to perfect working order up to now Careful tho, you do need to be confident in what you are doing or you will detsroy it.... LINK

[mick_318is]

If anyone needs a 320 AFM I have one spare. Yours for a zone donation.

[ProToZyKo]

Bobbydoughnut there was a connector going in to the throttle that was loose, i had forgot to put it back when changing the tube, but same problem after putting it back.
For some reason on the same cable there is another connector, looks like it has been out for a while, can't find where it is supposed to go, is this normal having connectors going no where :S? I have one connector under the throttle, one on the throttle and one on the AFM.
The rest you wrote i don't understand.

[Bobbydoughnut]

AS BM says, the system is cleverly balanced by the ECU and AFM and needs specialist set up, adjusting the screw only opens the throttle, needs set back, it doesn't source why you've bad idling, that's down to bad airflow control or bad cold start info to the ECU from the AFM/TS - check ECU wiring from the AFM just in case you disturbed that changing the main induction pipe and that every feed pipe from that is tight.
Check the Idle Cotrol Valve/speed control actuator (ICV) for correct operation, cleanliness and feed pipes - they can get gummed up, also the Temp Sensor (TS) for continuity.

Have you checked the above PRO?

[ProToZyKo]

I don't know what ICV is, i don't know where the TS is.
The wires looks ok, i can only find one connector that is just hanging there, don't know what is does, haven't been is use for some years by the look on it.
All pipes looks ok, everything should be in place. I haven't cleaned any pipes, wich one should i clean?

[Bobbydoughnut]

Sorry Pro, the Idle Control valve should look like no. 5 on this diagram -

This may need cleaned, and the pipework feeding it, bit of carb cleaner/brake dry clean spray.
Temp sensor is usually blue and underneath the inlet manifold, no.19 for the plug and 8 for the sensor, if you don't know how to check the sensor then a new one to rule it out but it isn't easy to replace due to access

have you checked that the plug on the AFM wasn't damaged when you were swapping it out, pins clean?

[ProToZyKo]

I went over all connectors yesterday and this morning it seems fine, but it has been warm today so maybe that's the reason, or one of the connectors had bad contact, i cleaned them all. The one under the throttle was a little filthy, but nice and clean now.
But i still have one connector going nowhere :S

[Bobbydoughnut]

Throttle Position sensor is the one under there, and it could have been a bad contact as you would have had to disturb the plugs when changing the inlet rubber, you may have got away with it being a dirty contact and nowt else...fingers crossed!

[ProToZyKo]

It seems fine now ;) prolly just a filthy contact, but i still have one that goes nowhere.