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        General >> Problems >> Tickover revs fluctuating
        
(Message started by: Jonnycab on Sep 12^th, 2008, 1:16am)

Title: Tickover revs fluctuating
Post by Jonnycab on Sep 12^th, 2008, 1:16am

Not a problem I've had before, so hopefully someone can give me a clue :)

On the wifes 2.3 estate, just after start up, the tickover will start to fluctuate between the normal 850 revs to about 1100 revs. It only happens for a minute or two when the engine is cold. When starting it from warm it's fine.

I've plugged my handheld scanner in & it's not come up with any fault codes. Checked for any air leaks in the inlet manifold & pipework, but none can be found & tried a spare IACV, which made no difference.

I'm thinking possibly a problem (when cold) with the fuel pressure regulator ? :-/

I've not really gone to town on trying to find out what is causing the surging revs, as it's not really a big problem, but if anyone has any suggestions as to the reason, it would be nice to sort it out ;)....... :)

Title: Re: Tickover revs fluctuating
Post by Snoopy on Sep 12^th, 2008, 7:34am

This sort of phenomenun seems to be IACV related from past history . Also make sure the inside of the air intake where the butterfly is , is clean and there is no build up of carbon, but I do advise caution as I undestand there is a coating on the inside which helps with air turbulance etc , BUT I don't know exactly what is there, but i am sure someone will soon be along to correct me and tell you correctly.

Title: Re: Tickover revs fluctuating
Post by Simmo on Sep 12^th, 2008, 7:44am

Jon, Snoopy is correct in that the IACV is the first suspect. The carbs do have a sticker inside the intake saying not to clean the interior as it is specially coated. However it is possible to clean the edges of the butterfly flap with a cotton bud or similar soaked in carb cleaner which will remove any carbon build up. ;) Mike.

Title: Re: Tickover revs fluctuating
Post by Tompion on Sep 12^th, 2008, 8:57am

on 09/12/08 at 07:44:42, Simmo wrote:

Jon, The carbs do have a sticker inside the intake saying not to clean the interior as it is specially coated. ;) Mike.

Don't spend too long looking for the carb ;)

Title: Re: Tickover revs fluctuating
Post by Highlander on Sep 12^th, 2008, 11:43am

Its Simmo, we have to make allowances for him, some days he wakes up in the 1930's ;)

Title: Re: Tickover revs fluctuating
Post by Jonnycab on Sep 12^th, 2008, 12:13pm

I've tried a different IACV & it made no difference. I did also (forgot to mention) clean the throttle & butterfly flap but this still has made no difference :)

Title: Re: Tickover revs fluctuating
Post by gozz on Sep 12^th, 2008, 8:34pm

Oi Highlander !
At least old Simmo wakes up ;D
GOZZ

Title: Re: Tickover revs fluctuating
Post by Simmo on Sep 12^th, 2008, 9:33pm

Now now lads !!. Thank you Gozz. ;D

Title: Re: Tickover revs fluctuating
Post by Jonnycab on Sep 14^th, 2008, 1:36am

Oi !!.....stop hijacking my post !! }{

Constructive answers only please ;D

P.S....I don't think that the special (sticky) coating behind the butterfly flap in the throttle is there to aid air turbulence :-/

From what I've read, it's supposedly there to trap any small nasties from entering the manifold :-/

This 'special coating' can be completely removed with no detrimental affects to the tickover or running of the Scorp :)

http://i70.photobucket.com/albums/i101/jonnycab/P6220073.jpg

The above pic is of the throttle that I cleaned out & put in my Scorp & it still ran fine :D

Title: Re: Tickover revs fluctuating
Post by Jonnycab on Sep 23^rd, 2008, 12:48pm

I had another little tinker about with the wifes Scorp the other day & discovered that if I pull off the vacuum pipe that goes from the throttle to the fuel pressure regulator at the throttle end, then the revs even out, although a little high.

There seems to be plenty of suction from the throttle body & the vacuum pipe has no splits in it, so it is leading me to believe that it may well be a problem with the fuel pressure regulator :-/

I've got a good spare, so I'll fit it when I've got a moment & see what happens :).....fingers crossed ;)

Title: Re: Tickover revs fluctuating
Post by Tompion on Sep 23^rd, 2008, 4:42pm

Diconnecting that hose increases the rail pressure by about half a bar at tickover.

Title: Re: Tickover revs fluctuating
Post by Jonnycab on Sep 23^rd, 2008, 5:03pm

on 09/23/08 at 16:42:14, Tompion wrote:

Diconnecting that hose increases the rail pressure by about half a bar at tickover.

Yes, I know...but it stablized the tickover at the higher revs......do you think I'm barking up the wrong tree ? :-/

Title: Re: Tickover revs fluctuating
Post by Tompion on Sep 23^rd, 2008, 7:18pm

Do you mean the revs are higher with the hole open on the manifold or with the hole plugged? I think mine revs higher with the hole open with a warm engine, no difference with the hole plugged.

Title: Re: Tickover revs fluctuating
Post by Jonnycab on Sep 24^th, 2008, 12:07am

Yep, the tickover is higher & constant with the hole open. Plug the hole & the revs obviously drop but tickover hunts up & down ???

Once the engine is warm then car ticks over fine at a constant 850 rpm ::)

I know the problem points toward the IACV, but in this case that isn't the problem as I know the spare IACV is good because I've tried it on my Scorp :)

Title: Re: Tickover revs fluctuating
Post by TRACEYS_LIMO on Sep 26^th, 2008, 8:10pm

hi jc have you checked or swapped your maf ???

Title: Re: Tickover revs fluctuating
Post by Jonnycab on Sep 27^th, 2008, 3:21am

No, haven't checked or swapped the MAF.....come to think of it, I haven't tried cleaning it yet either ::)

I'll give it a clean & if no difference I'll swap it over.......got a spare one of those too ;)

Thanks for the suggestion TL :)