Fast Idle

[kman82]

Hello everyone

Sadly another post on idling issues, I promise i have searched all the forums for answers but have specific questions not covered elsewhere. Sorry for this being such a long post but im trying to give you as much info as i can. I have 325i cab which starts ok and initially idles at 1000rpm then rises up to as high as 1800 - 2000!

So far i have checked the following:

- Air flow meter, checked gate inside moving freely and checked with ohmmeter for proper resistance as gate opens. All seem ok

- Idle control valve, when ignition is turned on ICV buzzes to life and resistances on plug seem to be ok. When the electrical connector for the ICV is removed the engine doesn't rev any faster suggesting that the ECU is telling the ICV to fully open?

- Hoses, the hose to and from ICV look like they've seen better days so i have ordered some new ones along with main hose from AFM to throttle body for good measure.

- Throttle position switch, This does not seem to click with the ignition on and throttle open so i removed the plug and tested with a circuit buzzer. It does not show any circuit on the appropriate pins with the throttle in closed position but does when 3/4 open.

My questions....

1. I am going to first attempt to remove the tps and give a good clean but will probably replace. Does anybody have any tips in removing. i.e. do you get under the car and unscrew just the switch or is removing the throttle body easier?

2. Can i attempt to trick the ECU into thinking the throttle is shut by inserted a piece of wire in the plug to see if this helps with idle?

3. How do you adjust the tps? I haven't got under the car to have a good look at how it works yet but do you rotate it slightly?

Thanks for reading and any help would be greatly appreciated.

[jay528ise1985]

If I was in this situation my first port of call would be to adjust/replace the tps.

I've found it really easy to just remove the throttle body from the inlet manifold (you'd ideally get a new gasket which is only a few pence from BMW), and it's then really easy to adjust the tps.

If after adjusting the tps still doesn't give an on idle signal then you know you need a replacement!

[kman82]

Thanks jay, Taking off the throttle body sounds a lot easier than trying to adjust from underneath. I'll let you know how i get on when my parts arrive in the week.

In the mean time does anybody know if i can put a jumper wire in the electrical connector for the tps to see if this helps with idle?

[kman82]

Update

Just sprayed carb cleaner in the idle control valve and the shutter inside moves pretty freely. Replaced hoses to and from ICV.

Did notice however in the main air boot from AFM to TB and to ICV some oil. I gave this a clean but no doubt the moment the engine is started will come back. Is this normal????

[kman82]

Throttle switch adjusted and she ticks over at 1k rpm - sorted!!

[kman82]

Sorry to bring this thread back to life again but im still having troubles... The idle is not as fixed as i first thought! On startup she ticks over at about 1000 - 1100 rpm which is cool. Doesn't annoy the neighbours too much in the morning but pretty much by the time i've got out of my road she's back ticking over at 1200 - 1300 which in my opinion is way too fast. Much improvement on before but i'd like to get it lower.

I've investigated the blue temperature sensor and got the following reading at the ECU connector:

3280 ohms when cold
225 at operating temperature

From what i've read these seem about right so can i rule out the blue sensor?

I've also had the ICV off again and ran voltage through it and it works perfectly. I checked the voltage the plug is sending and both outer sides (3 wire version) are getting about 6.7 volts which makes the ICV open exactly half way at operating temp and cold. Is that right????

[steve_k]

if you find out how to bring your idle back down let me know as hopefully it would be the reverse to raise mine back up (it's at 550rpm now).

like i say let me know how you get on.

[blingsta]

have you tried to adjust the throttle idle screw ?

[kman82]

have you tried to adjust the throttle idle screw ?

From what other people have said on here thats not really advisable? Masks other problems?

Im tempted to try it though

[asmith88]

have you tried to adjust the throttle idle screw ?

worth a try but has the car always done it or only just started?

[asmith88]

if you find out how to bring your idle back down let me know as hopefully it would be the reverse to raise mine back up (it's at 550rpm now).

like i say let me know how you get on.

ordered my blue temp sensor yesterday.. will get it fitted tomorow and let you klnow if it helps my idle problem

[ucpsale]

The first thing i would do is disconnect the throttle cable hold it up and drip some 3in1 oil down inside it, also oil the links around the throttle pedal.

[steve_k]

if you find out how to bring your idle back down let me know as hopefully it would be the reverse to raise mine back up (it's at 550rpm now).

like i say let me know how you get on.

ordered my blue temp sensor yesterday.. will get it fitted tomorow and let you klnow if it helps my idle problem

cheer's fella i'll keep my eye's open for this thread.

[e301988325i]

The first thing i would do is disconnect the throttle cable hold it up and drip some 3in1 oil down inside it, also oil the links around the throttle pedal.

Mine had a similar problem when I got it, throttle cable sticking and not closing fully.

The problem sounds like an air leak that gets worse when warm, split rubber pipe? breather hose to rocker cover?

[kman82]

Ok so i've been out and had a look at the throttle cable. Seems ok.

I had a look at the throttle idle screw while i was there and noticed the butterfly? wasn't even tooching this and there was a build up of gunk betweeb the two. I cleaned that off and slackened the allerator cable slightly but still the butterfly stays about a mm away. If you 'help' the butterfly return back to fully closed the rev's drop to 800rpm!

Is there any adjustment on the butterfly springs at all to position it better? I noticed a bolt on the top? or am i better off with a new one?

[e301988325i]

Clean inside the throttle body, take it off if required, probably gunk around the buttterfly. . . there's no adjustment built into the springs.