Z3MCoupe.com Forums

Go Back   Z3MCoupe.com Forums > M Coupé Technical > Technical Discussion
HOME Gallery Register Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #1  
Old 02-05-2008, 10:08 AM
glynmar's Avatar
glynmar glynmar is offline
Senior Member
 
Join Date: Jul 2007
Location: Reading
Posts: 160
Default Uneven Idle with aircon switched on

I picked up my S50 last Saturday and on the way back I switched the aircon on as we actually had some sun. This caused the engine to bounce between 600 -1200 rev when idling. If I switched off the aircon it went back to normal.

I test drove a couple of other S50's and one of them was on a hot day and it did exactly the same. Is this common or normal? Mine has a brand new Vanos so I know it's not that.

I love the car and have been waiting a year to buy one.
Reply With Quote
  #2  
Old 02-05-2008, 11:07 AM
c_w's Avatar
c_w c_w is offline
Moderator
 
Join Date: Aug 2005
Location: North West
Posts: 8,343
Default

If anything there should be a slight increase in idle speed when the aircon is switched on, you can also feel it when driving at low speeds; when you switch it on it feels on mine that it seems to drive itself at low speeds if that makes sense. As though there is extra throttle automatically added, probably via the idle control valve.
Reply With Quote
  #3  
Old 02-05-2008, 11:09 AM
DavidC's Avatar
DavidC DavidC is offline
Senior Member
 
Join Date: Oct 2004
Location: London, UK
Posts: 441
Send a message via MSN to DavidC
Default

I don't know how the aircon pump is activated, but if it's an electronic/magnetic clutch on the aircon pulley, could this or the aircon belt be slipping?
Reply With Quote
  #4  
Old 02-05-2008, 11:23 AM
MCOUP MCOUP is offline
Member
 
Join Date: Feb 2007
Posts: 85
Default Dirty or faulty idle control valve

hi mate,

congrats on the new car!!!

I had the same issue just over a year ago due to the idle control valve being too dirty... the control valve is located under those 6 intake trumpets and you can pull it out and clean the unit up a bit with some WD-40.... I actually bought a clean used one and swap it straight in (just in case my was broken, and also I have a spare one)... the idle has been steady ever since with/without the A/C

hope it helps!

cheers,

richie
__________________
M Coupe from Australia
Reply With Quote
  #5  
Old 02-05-2008, 03:23 PM
glynmar's Avatar
glynmar glynmar is offline
Senior Member
 
Join Date: Jul 2007
Location: Reading
Posts: 160
Default

Thank you all for your prompt replies. it sounds like a simple solution. I will investigate the idle control valve

Thanks Glyn
Reply With Quote
  #6  
Old 05-05-2008, 10:58 AM
wadh0070's Avatar
wadh0070 wadh0070 is offline
Senior Member
 
Join Date: Feb 2007
Location: Tonbridge
Posts: 405
Default

Quote:
Originally Posted by c_w View Post
If anything there should be a slight increase in idle speed when the aircon is switched on, you can also feel it when driving at low speeds; when you switch it on it feels on mine that it seems to drive itself at low speeds if that makes sense. As though there is extra throttle automatically added, probably via the idle control valve.
I turned the AC on yesterday for pretty much the first time and was surprised when in traffic the car seemed more lively without any right foot. Exactly as you described.

Jez
__________________
1998 Cosmos Black - Not quite standard ...
Reply With Quote
  #7  
Old 09-05-2008, 01:03 PM
wadh0070's Avatar
wadh0070 wadh0070 is offline
Senior Member
 
Join Date: Feb 2007
Location: Tonbridge
Posts: 405
Default

Quote:
Originally Posted by glynmar View Post
Thank you all for your prompt replies. it sounds like a simple solution. I will investigate the idle control valve

Thanks Glyn
Did this cure it? I ask, as mine is now doing *EXACTLY* the same. 600-1,200 with aircon on. 800 with aircon off.

If you've cured it, I'm going to come back and ask (with my stupid hat on) *EXACTLY* which piece I need to clean. With pictures or something (looks sheepish).

Jez
__________________
1998 Cosmos Black - Not quite standard ...
Reply With Quote
  #8  
Old 12-05-2008, 06:12 PM
speed8 speed8 is offline
Senior Member
 
Join Date: Jul 2006
Posts: 213
Default

Quote:
Originally Posted by wadh0070 View Post
Did this cure it? I ask, as mine is now doing *EXACTLY* the same. 600-1,200 with aircon on. 800 with aircon off.

If you've cured it, I'm going to come back and ask (with my stupid hat on) *EXACTLY* which piece I need to clean. With pictures or something (looks sheepish).

Jez
If you end up looking for the ICV I posted a few pictures in this thread about where it is.

http://www.z3mcoupe.com/forum/showthread.php?t=5116

It's a bit of a bitch to get to but if you have small hands and a gymnasts flexibility then you should be fine ;)
Reply With Quote
  #9  
Old 12-05-2008, 06:48 PM
h4pry's Avatar
h4pry h4pry is offline
Moderator
 
Join Date: Dec 2005
Location: Kent
Posts: 1,334
Default

Another pic:

http://www.z3mcoupe.com/forum/showth...?t=4254&page=4

__________________
Out: 99 S50 Titan Silver V876 KKO
In: 98 S50 Estoril.......
Reply With Quote
  #10  
Old 31-05-2008, 07:27 PM
glynmar's Avatar
glynmar glynmar is offline
Senior Member
 
Join Date: Jul 2007
Location: Reading
Posts: 160
Default

Sorry for the delay in posting a reply. The problem was sorted out today. Turned out to be the AIRCON needed regassing. As on my car a dye can be put in the system so that if you use a ultra violet light it will show up any leaks on the system.

Reply With Quote
Reply

Tags
a/c, aircon, idle

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 07:30 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2018, vBulletin Solutions, Inc.