This is a weird A/C Rev's issue!!!

[fildigger]

So, I just picked up my very first VX today.....while driving along in 4th at around 60mph, i decided to turn on the A/C and put the temp' to minimum.....the transmission immediately dropped down to 3rd (almost if i had hit the kickdown!!!)...

..within a few seconds it is back up to 4th for several seconds and then i guess when the A/C compressor kicks-in again it drops back down to 3rd gear !!

Not only that but just before i decided to turn off the A/C (the VX didn't like it, seemed all wrong to me)...The Engine Check light came on :mady:

Anybody experienced this before?...if not, any ideas why such a thing should happen?...(never had this in any automatic car before!!!)



ps. i have also got erratic idle now as well :(..but that may be unrelated!...bare in mind, i have only just bought the VX...not happy at the moment!!!

[atilla_the_fun]

You are going to have to read the code, then come back and ask. The A/C issue is strange, but if you have an erratic idle that may be related to the kickdown situation than the A/C.

Turn the A/C on at idle and note the idle, see how it changes without being in motion. The car should increase idle to compensate for the A/C compressor energy loss.

[fildigger]

OK...I have removed the battery terminals for 10 mins and replaced...the CEL has gone out :smilegray...(i will have to take it to my local repair shop to check any old codes.

I have just sat in the car for 20 mins (not touching the gas pedal) I have been watching the rev counter..:yeso:

It stayed at 850 rpm for a few minutes
Then i hit the A/C, within a few secs it was up to 1700 rpm
few seconds later its down to 850 rpm (all seems normal ?)

Then it raises to 1200 rpm for a few secs, then compressor kicks in and it's back up to 1700 revs.

does this for a 3-4 minutes.

I decide to turn the air con off to see what happens......it idles at 850 but then raises to around 1200 rpm with a slight hunting of the revs!...it carries on like this for a few minutes....

...Then, all of a sudden the engine Dies :confused:

It fires up again straight away but revs are at 1200 rpm and not the required 850-ish !!!

I have a Problem :_thinking

[atilla_the_fun]

It could be an intake gasket or fuel delivery.. search for rev or idle issues on this site. see here: http://www.vehicross.info/forums/showthread.php?t=19240

Try the carb-cleaner sprayed around the intake gasket area tip. Get some carb cleaner and if your idle changes when you spray the cleaner around the common chamber area you have an intake gasket leak.

[fildigger]

It could be an intake gasket or fuel delivery.. search for rev or idle issues on this site. see here: http://www.vehicross.info/forums/showthread.php?t=19240

Try the carb-cleaner sprayed around the intake gasket area tip. Get some carb cleaner and if your idle changes when you spray the cleaner around the common chamber area you have an intake gasket leak.

Thanks for the help atilla...much appreciated :thumbup:

It's nearly 10 pm over here, so will be giving it the Carb' cleaner treatment in the morning.......will get back with the answer on my findings

ps. if it isn't the intakes, then i may have a go at cleaning the IAC, have a look at TPS and maybe the EGR!!.........Worth noting the vehicle has only done 37K miles though !!!

[etlsport]

Take a look at this thread. It has some good info on normal engine operation with and without AC at idle


http://vehicross.info/forums/showthread.php?t=18045&highlight=Scangauge

[Paul_A]

Uh Oh... Phil,
That sounds awfully familiar... :(
That's exactly how mine started out.... Intake gaskets.
I don't think it's relevant how many miles the engine's done... it happens.
And yeah.... It's a PIG of a job!
Hope you had a warranty on it..... :(
Wish you were a bit closer so I could have hooked it up to my code reader/laptop.
BTW "Easy Start" seems to work better than carb cleaner to test.
I just thought... before you go wasting money (like I did) on Tps's and Iac valves why don't you pop your phone number on a p.m. to me ... I can likely help you figure this out.

[fildigger]

An Update......

Took the battery terminals off, replaced 10 mins later and the CEL is now OFF :grino:

Ran the engine on tickover and sprayed 'Easy Start' around the whole of the inlet manifold...There was no change at all in the idling of the engine :smilegray

So, after this, I fired her up this morning and went on a short shopping spree...the VX is idling fine! no hunting ! and no surging when decelerating !!...I'm pleased but still sceptical :confused:

Took her out again this afternoon, for a longer and more spirited drive and everything is absolutely fine !!

OK, so some threads/posts on here state that this erratic idle situation can suddenly disappear and then all of a sudden come back...

...with this in mind i thought i would set to and have a poke around under the hood.....Now i just happen to have from my Diesel days a can of Wynns EGR cleaner...here,,
http://www.wynnoil.co.uk/products-wynns-featured-egr3-diesel.htm

Before you say anything, i do know the V6 is a petrol engine :rolly:....this stuff essentially does what a carb' cleaner will do but maybe in a more aggressive way.

Took the IAC valve off, exposed the throttle body butterfly and removed the PCV valve...they all got a good dose of the EGR cleaner and are now looking like new (to the eye)....bolted everything back up, then opened the air filter box, ran the engine and squirted copious amounts of the stuff in the air induction pipe to clean the MAF (it does say on the can, ideal and safe on Air sensors)......

...Went for yet another run out and it's running like a dream :dance:..So the erratic idle MAY be sorted !!!!!

I am not going to get over confident here!!!...will be going to work in the VX tomorrow and i will be hitting the A/C button (temp' on minimum) while at speed and see if the wierd dropping a gear down to 3rd happens again when the A/C compressor kicks in!!!

I'll Be Back ;)