2007 fx35 in need of your help experts

Y

ymizyed

Member
Location
Dubai UAE
Car
Fx35 2007
My car has developed an internment situation that i'll try my best to describe:
Since it has been extremely hot lately 43+ C degrees i'm noticing that the idle is higher than usual around 1100 specially when the car has been started when worm/hot. During driving its sounds different when the AC is on but goes back to normal when the AC is off and the rpm will take around 1 minute to go down to regular 600. The last major thing done was the radiator change and there are no leaks whatsoever. Please share your inputs on the same if you have ideas ;-)
 
It is intermittent when the AC is on or it happens always when the AC is on?
Do you have a MIL?
Do you hear a moaning noise when you AC is on?
Does your AC provide sufficient cooling?
Is the engine temperature stable in all situations you described above?

Sent from my iPad HD
 
Well, it happens when the AC is On always when the outside temp is extremely hot, the temperature gage is stable and the coolant is always at fixed level with sufficient AC cooling , No lights on the dash and i hear the abnormal sound during acceleration but don't know the exact source, ~1 minute after shutting off the AC will get back to normal
Thanks for the response
 
Ok you do not seem to have an ECU/ECM issue, otherwise I would have advised you to perform accelerator pedal released position learning, throttle valve closed position learning and idle air volume learning.

The issue seems to be purely mechanical, I am suspecting the AC clutch bearings are out, and it is causing the engine to exert the extra RPM's at idle to overcome the friction and avoid shutting off, you could confirm this by opening the hood and trying to listen carefully to find out where the noise is coming from, I am sure it will be right at the AC clutch. While you are at it, check the condition of the AC drive belt.


Sent from my iPad HD
 
Thanks for the advice and will get this clutch bearing checked and post updates, the belts are less than 15k km old but i'm suspecting their tension also
 
The FX engine has auto tensioners so tension is auto-mechanically adjusted, if there is a tension problem then your RPM will go high with or without AC on. What is the mileage on your car anyway?


Sent from my iPad
 
I've just hit the 111111 KM milage, i've seen couple of threads here on IS about the belts tension and that they should have some movement when hot and mine don't so this could be the reason of the bearing or pulleys got bad, i'll have the dealer check on those my next visit.
 
Correct me if I'm wrong. The FX35 does not have auto tensioner like FX45. The tensioners are manually adjusted with via a bolt on each one.
 
la_fx35 said:
Correct me if I'm wrong. The FX35 does not have auto tensioner like FX45. The tensioners are manually adjusted with via a bolt on each one.
Click to expand...

You are right Andy, I assumed it is the same as the FX45.


Sent from my iPad

---------- Post added at 09:13 PM ---------- Previous post was at 08:42 PM ----------
ymizyed said:
I've just hit the 111111 KM milage, i've seen couple of threads here on IS about the belts tension and that they should have some movement when hot and mine don't so this could be the reason of the bearing or pulleys got bad, i'll have the dealer check on those my next visit.
Click to expand...

Yes, it makes a lot of sense.


Sent from my iPad
 
Update: got my fx back from the dealer after mentioning the issue, they conducted the 110k service. The service advisor noted they found the belts loose and tensioned to specs. Now i feel the engine is louder but didn't get the chance to monitor and check the higher idle issue ;-(


Sent from my iPhone
 
It sounds like the AC compressor/clutch. Improperly tensioned belts shouldn't cause the issue because they're always spinning anyways. If it's only a problem when the compressor engages, then I'd look at that.
 
I would say your engine is just idling higher to provide the power to run the ac compressor.
The ac compressor is a type with a variable displacement and i'm guessing you compressor has a hard time to keep the car cool so running at full stroke.
This consumes a lot of power and engine manangment will give the engine power required.
This also pulls hard on the belt so it might start to make more noise.

If you want to check the bearings of the pulley's, remove the belt and check each pulley for radial and axial play.....there should be none at all.

Edit: And yes, for the FX35 the tensioners are manually adjusted and do not provide any automatic tensioning.
 
Last edited:
But idling at 1100 vs. 600 is a huge difference. Normally, it should be maybe 100rpm difference if that. I look at mine and even when it is 100 degrees out, the rpm's barely move at idle when I turn the AC on.
 
The rpm is increased by the ECM as he detects engine load.
We all know how bad influence an ac compressor has on fuel economy so there is quite some power drawn from the engine.
 
Guess a compressor like that requires something like 5-6 hp to be run.
It's a compact unit but as i said it's a variable displacement one and can do quite some heavy work for it's size.

If the bearings are not collapsed, the electro magnetic clutch is functioning and the belt is in good condition and on the correct tension i can not see what could be wrong.
At the same time the cooling fans also need to be run for the condensor and cooling system which in their turn also increase the rpm a bit as the fan also consumes quite some power.
 
Last edited:
I agree with shadow, which is in line with what I mentioned earlier, it is not normal to idle at 1100 rpm when turning AC on. Me too when my AC is on my idle goes up by 100 rpm max.

Here is how it relates to a clutch / bearing issue:

1) rpm increases when AC is on > problem is definitely related to either AC or AC clutch / bearing, I doubted if it was belt tension, which if was the case then it would create a problem with or without AC on.
2) the OP stated that AC provides sufficient cooling plus no grinding / whining noise from engine compartment when AC is on > problem is definitely related to AC clutch / bearing, AC itself is fine.





Sent from my iPad
 
The belt can still cause problems when it's slack, when the ac is not in use it's just rotating but when the ac kicks on there is a lot of tension coming on the belt.
If the adjustment is not good you can get slip under load.
 
Thank you all for the info and support, visually i can't see something wrong with the pulleys and they look to be spinning fine. the AC clutch is engaging and dis-engaging normally without issues. the higher idle occurs at when all the below conditions are met:
1. outside temp very high
2. ac is on
3. compressor engaged
4. stuck in traffic / stop and go drive
5. both radiator fans are on

I've noticed that when the fan stops the idle goes down around 100 rpm and after i turn the AC off ~1 minute the idle goes back to normal 600
my concern is the sound (don't know the exact term for it, like something rotating under high load) that is happening when the above conditions are met
 
You must log in or register to reply here.
Back
Top