Revs drop on cold run with A/C on ( faulty engine mounts?)

**Type-R** · 25-11-2009 06:58 PM

Hi All,

My 1.5 CVT jazz has started to do something strange over the last 10 months when the A/C is on. What happens is if I start my car after work (after it has been parked for 8 hours) and put the a/c on, when i stop at the first and sometimes the second set of traffic lights (within the first 2-5 mins of starting) the revs will drop down from about 1,050 to about 700 and the idle gets very rough (it feels like it may stall, even though the revs don’t drop down to stall level).....it will then very quickly go back up to 1000 (like some anti-stall system cuts in), and then do it again once more (it is not correlated to the compressor cutting in though).

If you go to accelerate softly during this time, the car won’t go for a sec (again idles very hard before it decides to go). The strange thing is it won’t do it again at the next set of lights if it has been about 5 mins since start.

I did a bit of research on the web and found that people who have had hard idel have had to replace their engine mounts on their Jazz’s at about 80k. My car has done 82,000. But i find it hard to believe that such a new car will need engine mounts....?

Any ideas about cause / engine mount theory would be greatly appreciated!

**bestjazz101** · 26-11-2009 01:53 AM

my jazz is abit like that...but i think its coz of the turbo i put in... hmmmmmm

**95331140** · 28-11-2009 01:49 PM

I also have the delay when accelerating from start with the air-conditioning on.

Though, I've always had this issue with all cars I've had...I've only had 1.6L and below cars. When I drive my dad's civic 1.8L, I don't feel any hesitation.

Driving an automatic, 1.5L with Air-conditioning on, I'm not really surprised. Air-conditioning really sucks power from small engines.

**hiko** · 30-11-2009 01:18 PM

i have a 06' vtsi manual jazz and i too have recently got this problem, with the air con on and starting the car from idle it appears its lacking response it would take take off abit rough as if its in 2nd gear i've recently got the car serviced but havent gotten the guys to check the air con although it will need to be regassed soon.

also i've noticed some knocking clunking noise from under the car from time to time this only happens with the air con on.

there is only 1 variable here which is the air con causing these issues..
i am taking my car in soon to get the air con serviced and regassed hope this fixes the problem.

**Type-R** · 30-11-2009 05:23 PM

Thanks for everyone’s replies!

Hiko, mine sounds to be doing exactly the same and will do the thing with the revs occasionally when sitting at the lights at idle... though mine is an Auto.

I know its a small engine car and will suffer with the A/C, but having owned it for the last 3 years, it has only recently started being rough with the A/C on. From what i have found, I somehow think it is related to the engine mounts...

The company that i work at has a 1.3 06 Jazz Gli Auto and goes much better with the A/C on even when taking off than my 03 1.5 VTI-S.

Hiko if u find an answer for your car, please let me know. BTW what makes u think u need to re-gassed your A/C? Is it not cooling that well?

**hiko** · 01-12-2009 10:25 AM

yeh its not cooling that well at all, i reckon a pipe is loose or needs servicing the air con units also noticed in the foot space its also blowing out warm/hot air even with no aircon or anything turned on. something must be directing that in there too.

the car feels like its about to fall apart especially if i try to push the revs over 3k it will just jerk back and forth a few times with the occasional clunking noise from the bottom of the car.

unfortunately i wont be taking my car to my mechanic til i get paid in 2 weeks time

**Poeter** · 09-12-2009 12:55 PM

Why would the engine mount having anything to do with the a/c?

They just merely hold down your engine to the chassis as far as I know.

When they fail you will feel more vibration. But by no means should they cause your revs to drop.

It is also possible that your battery is near its end of life.

**lithium** · 09-12-2009 01:30 PM

yeah a shagged engine mount sounds unlikely to be related to low idle when the A/C is on

first guess is that your idle control valve is sticking as it is gunked up with carbon. clean it and while you're at it, clean the throttle body too. it's easy enough to do yourself - or ask your mechanic to do it for you next service

**Poeter** · 09-12-2009 01:36 PM

Originally Posted by lithium

yeah a shagged engine mount sounds unlikely to be related to low idle when the A/C is on

first guess is that your idle control valve is sticking as it is gunked up with carbon. clean it and while you're at it, clean the throttle body too. it's easy enough to do yourself - or ask your mechanic to do it for you next service

Interesting...Where is the idle control value located?

**lithium** · 09-12-2009 02:14 PM

Originally Posted by Poeter

Interesting...Where is the idle control value located?

i've never worked on a Jazz before, however the ICV is always connected to and near the throttle body. is there a pic somewhere of a Jazz engine? i could point it out

**hisoka** · 09-12-2009 02:21 PM

i have this in my subaru. drops and sometimes even stalls.

**lithium** · 09-12-2009 02:58 PM

Originally Posted by hisoka

i have this in my subaru. drops and sometimes even stalls.

try cleaning the throttle body/ICV

also do you have your Subaru serviced at a Subaru dealer? if not remember to run Subie upper engine cleaner through your engine every service or second service. the boxer design tends to gunk up the intake manifold quickly