|
||
|
31st May 2013, 10:31 | #1 |
Newbie
MG ZT Cdti Join Date: Mar 2011
Location: Limerick
Posts: 17
Thanks: 5
Thanked 1 Time in 1 Post
|
Rough Idle when Air Con is On
As title says my zt cdti will idle normally if the aircon is off however if the car is left idle and aircon is on the idle is rough with revs increase slightly and then drop off. Turn off the aircon and it will idle prefectly smooth again. I presume the aircon is loading the engine somewhat. Is this normal? Its rather annoying if your stuck in traffic around town.
|
31st May 2013, 11:03 | #2 |
Loves to post
None at the moment Join Date: Dec 2010
Location: Stanford - Le - Hope
Posts: 333
Thanks: 3
Thanked 5 Times in 3 Posts
|
Sorry missed cdti bit
Aircon compressor does put a slight load on engine and drop in revs slightly but shouldn't be massive. Last edited by Click4; 31st May 2013 at 11:40.. |
31st May 2013, 14:11 | #3 |
This is my second home
Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009
Location: Hampshire
Posts: 11,550
Thanks: 3,470
Thanked 3,119 Times in 2,247 Posts
|
Thought you might have done Click.
|
31st May 2013, 19:37 | #4 | |
Doesn't do things by halves
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,381
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
|
Quote:
Check the crankshaft pulley. On the diesel the multi-layer construction is prone to weaken and eventually fail. It could be that the extra load of the air conditioning compressor is putting additional stress on the pulley and affecting the idle. Simon
__________________
"Whatever is rightly done, however humble, is noble." Sir Henry Royce. |
|
31st May 2013, 21:29 | #5 |
Regular poster
MG ZT-T 2005 CDTi 135 Join Date: Nov 2011
Location: FOLKESTONE
Posts: 93
Thanks: 0
Thanked 0 Times in 0 Posts
|
The ECU should detect the extra load when the a/c is turned on and adjust the idle speed accordingly but I am not sure what sensors it uses to do this.
|
5th June 2013, 11:15 | #6 |
Newbie
MG ZT Cdti Join Date: Mar 2011
Location: Limerick
Posts: 17
Thanks: 5
Thanked 1 Time in 1 Post
|
Cheers guys thanks for help. I've been offline for last few days bank holiday weekend over here so only following up posts now.
|
3rd September 2020, 21:10 | #7 |
Avid contributor
Rover 75 CDTI Tourer Automatic Join Date: Mar 2015
Location: Dunstable
Posts: 196
Thanks: 4
Thanked 31 Times in 22 Posts
|
I'm getting exactly the same.
Is there anyone on here that has resolved this?
__________________
300,000 miles and back on the road Jobs done: Everything you can possibly imagine ... I have the "Triggers Broom" of cars. |
4th September 2020, 07:04 | #8 |
Doesn't do things by halves
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,381
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
|
As said above David, crankshaft pulley breakdown is the prime suspect. I'd suggest removing the wheelarch liner and carrying out an inspection.
Simon
__________________
"Whatever is rightly done, however humble, is noble." Sir Henry Royce. |
4th September 2020, 12:47 | #9 |
Avid contributor
Rover 75 CDTI Tourer Automatic Join Date: Mar 2015
Location: Dunstable
Posts: 196
Thanks: 4
Thanked 31 Times in 22 Posts
|
I'm unsure what I am looking for.
The pulley isn't noisy and I'm not sure I'll see much without taking the belts off. Any ideas?
__________________
300,000 miles and back on the road Jobs done: Everything you can possibly imagine ... I have the "Triggers Broom" of cars. |
4th September 2020, 14:06 | #10 |
Doesn't do things by halves
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,381
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
|
There is plenty of information about this on the forum David. The diesel crankshaft pulley isn't solid metal; it is constructed partly using a flexible rubber-like material. It is this which fails. If you use the Google search facility at the top of this page you will find out all you need to know.
Simon
__________________
"Whatever is rightly done, however humble, is noble." Sir Henry Royce. |
|
|