hunting idle

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hunting idle

Post by simmo116 on Tue Oct 01, 2013 6:15 pm

so thankfully the father in-law sorted out my timing and I hadn't buggered anything up. Phew!

but now it is hunting at idle it was doing it before I had it to bits. have filled the system and bled it.windscreen heater blows hot but others are luke warm
radiator pipes are all redders. am at a loss when I wiggle what I believe is the idle control valve it stops but is gonna cost me a fortune in fuel? have read that it could be a symptom of head failure but have no smoke out the back but with out a test I cant be sure.
what are your thoughts guys?
thanx
rich

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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 6:17 pm

its the 993 efi model

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Re: hunting idle

Post by PFM on Tue Oct 01, 2013 6:56 pm

The only time mine's done that is when coolant level is low. Air from screen vents and footwell vents go through the heater matrix so should both be same temp - face vents are always cold.

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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 6:59 pm

ok just topped up the coolant. only took a smidge. can you still have HG failure if all pipes are hot,heater working and fan working etc

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Re: hunting idle

Post by PFM on Tue Oct 01, 2013 7:08 pm

Yes, but as you say fiddling with the idle control valve stops it, that might be the problem. HJ may know, he'll be along shortly.

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Re: hunting idle

Post by HighlyJetted on Tue Oct 01, 2013 7:44 pm

Yeah, bleed the idle control valve via the pipe that goes to the cylinder head, make sure your getting water through the idle control valve.

That would be my first port of call.

After that look for vacuum leaks e.g. leaking injector seals, manifold gasket, some vacuum pipe you've forgotten to attach or broken in the process. On the 993 I'd have a close look at the pipe to the MAP sensor under the hand brake.

Your nearly there.

Learning much along the way?
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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 7:53 pm

yes learning loads. am enjoying getting my hands dirty. was relived the timing wasn't much out. could that pipe be blocked? as in some other the other conversations regarding small clogged water hoses?

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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 7:55 pm

what does the map sensor do? a load of pipes popped off when I took the centre column out..
id like to say thanx for all the help and advice I've had from this site.
cheers guys.

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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 7:56 pm

oh I forgot to mention that ht leads 2 and 3 are corroded at the dizzy? could this have anything to do with it?

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Re: hunting idle

Post by PFM on Tue Oct 01, 2013 7:56 pm

HighlyJetted wrote:Yeah, bleed the idle control valve via the pipe that goes to the cylinder head, make sure your getting water through the idle control valve.
When you have a minute, I for one would appreciate a little more info on doing this.

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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 8:02 pm

PFM wrote:
HighlyJetted wrote:Yeah, bleed the idle control valve via the pipe that goes to the cylinder head, make sure your getting water through the idle control valve.
When you have a minute, I for one would appreciate a little more info on doing this.
yes a picture or diagram would be great thanx.
Very Happy 

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Re: hunting idle

Post by HighlyJetted on Tue Oct 01, 2013 8:18 pm

Bloody hell.... hang on let me write one of those big phat posts...
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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 8:53 pm

lol
Very Happy 

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Re: hunting idle

Post by HighlyJetted on Tue Oct 01, 2013 8:55 pm

Forget the dizzy unless its misfiring.



MAP sensor measures the vacuum created in the inlet manifold - cause by the engine sucking in air and the throttle being open or closed. This vaccum manages fuelling amount by the electronics/software in the ecu.

But the sensor won't be the cause. The rubber pipe that feeds it breaks, cracks and splits. This causes a vacuum leak so it idles too high as it is sucking in air where it shouldn't be.

That is just one possibility.



The idle control valve, is part of the throttle assembly. I do not know the 993cc engines so you'll have to forgive me for minor errors in exact locations of pipes etc.

Firstly we have a diagram of the throttle body (this is for a 1.3, I have dug hard and cannot find one for a 992cc but will be very similar)
Notice the two tubes sticking out the bottom of it. One is coolant/water in - and one is coolant/water out.



Next I have a diagram for the cylinder head and pipe work, this is for the 993cc.



Notice the red dot, this is a feed pipe that goes to the throttle body.

Where the return plumbs in you'll have to work that out yourself!

All you need to do is:-

Anywhere on the idle control valve coolant piping - in or out doesn't matter - you need to undo a pipe clip while its cold and slip a pipe off and then back on so you know it its loose.

Next warm up the engine a little bit so the water is expanding, only takes a minute ticking over.

Now - VERY F***ING CAREFULLY (as the water may come out pretty hot - it might just be luke warm too)

Pull of the loose pipe.

Put your finger over the rubber hose, make sure water comes from the opposite pipe fitting.

Then put your finger over the "opposite pipe fitting" and let water come from the hose.

Because the water is expanding it will expand out of either side quite happily as long as the other is "bunged" with your finger etc.


THEN - very quickly take your fingers off both bits, and slip the pipe back on and slip the hose clip back to where it should be and re-tighten etc if applicable.




You can make this a safer procedure if your a fanny or incident prone, by disconnecting the hose, use a brake hose clamp on the rubber hose, and make a bung out of a bit of rubber pipe and a bolt etc for the metal pipe fitting part.


Understand?
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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 9:08 pm

"You can make this a safer procedure if your a fanny or incident prone, by disconnecting the hose, use a brake hose clamp on the rubber hose, and make a bung out of a bit of rubber pipe and a bolt etc for the metal pipe fitting part".


Understand?[/quote]
got to admit I am quite incident prone lol.
thanx hj shall give it a go tomorrow.
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Re: hunting idle

Post by HighlyJetted on Tue Oct 01, 2013 9:09 pm




Wink Laughing Laughing Laughing 
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Re: hunting idle

Post by simmo116 on Tue Oct 01, 2013 10:31 pm

still got something in me eye!

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Re: hunting idle

Post by PFM on Wed Oct 02, 2013 7:50 am

Brilliant, HJ - top man. Just a few dozen more articles like that and you'll have the makings of a 'Haynes' manual Very Happy 

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Re: hunting idle

Post by simmo116 on Wed Oct 02, 2013 1:16 pm

Asked my mechanic friend today about my van hunting high and low.he Replied ah ha!
Not sure if he knew what I was on about. Lol

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Re: hunting idle

Post by simmo116 on Wed Oct 02, 2013 6:09 pm

ok couldn't find what you were talking about.
here is the noise my van is making when up to temp.



all hoses are hot and heaters blow hot as they should when I adjust the idle control it stops but is reving higher than it should.



checked what vac lines I could see and they all seem fine.
am at a loss now as to what to do.

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Re: hunting idle

Post by HighlyJetted on Wed Oct 02, 2013 6:52 pm

"I believe this to be idle control" - Afraid not, that's the throttle position sensor.

Not sure what that other pipe is, but doubt its coolant return/feed as the pipe is too big.

My stab in the dark would be this one:-



That is because it is about the right thickness, and it has a metal hose clip to stop it popping off.

The return might be underneath the throttle assembly.
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Re: hunting idle

Post by simmo116 on Wed Oct 02, 2013 7:14 pm

ok. when I unclip the throttle position sensor it stops hunting but revs are higher than normal idle speed. ill try that one when I get back from the big smoke on Monday. all I need is a pair of dolls hands to get in there now lol .
so is the idle control set by ecu?

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Re: hunting idle

Post by HighlyJetted on Wed Oct 02, 2013 7:37 pm

When you unplug the throttle position sensor,

The ecu no longer tries to make it idle, as it no longer knows the throttle is closed. Thus the hunting stops.


The idle is partly controlled by the ECU, what it has is a "target idle speed" say 900 rpm, and if its above that it retards the ignition timing and fuelling to try to pull the idle back down.

There is a screw under the rubber cover that is set at the factory which controls the air gap that maintains the idle speed. This will be set perfectly.


I would 100% say its either the water isn't going round the idle control valve OR you have a minor vacuum leak. I would totally remove the possibility of the idle control valve bleeding before I spent too long hunting for the vacuum leak. Because bleeding the idle control valve takes minute.
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Re: hunting idle

Post by simmo116 on Wed Oct 02, 2013 7:43 pm

and that's the (green) hose you highlighted?

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Re: hunting idle

Post by rich the mechanic on Wed Oct 02, 2013 8:07 pm

Right I have a 993 and if I have had an empty water system for any reason on fill up it will hunt for a couple of days running into work and back and topping up just a smidge each morning, it will rev like mad to start off with when the engine is cold as the idle control valve is near the top I have never had to bleed it other than the rad cap engine top pipe cap and the heater matrix bleed pipe.
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Re: hunting idle

Post by HighlyJetted on Wed Oct 02, 2013 10:27 pm

As I saw one in the garage, I thought I would take a photo of an idle speed control valve, although its off a 1.3

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