Idle problems (Help)
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Idle problems (Help)
I've got a major idle issue possibly of my own making and would be grateful of any help.
The idle has been erratic for a while but not too bad so whilst i had the day off i thought i would clean the ICV as per instructions i found on this site.
Put it all back together and it idles at 1500 rpm when cold but as the engine warmed instead of dropping to a normal idle it starts pulsating between 12-1500 rpm constantly.
I checked i had put everything back as it came off and even replaced a couple of old looking vac pipes but still the same.
Thinking i did some damage cleaning the ICV i got a new one but it made no difference. Now i'm stuck and due to go on Hols Saturday and none of the garages can fit me in before then.
Anyone any ideas i can try before the family lynch me.
Cheers
Colin
The idle has been erratic for a while but not too bad so whilst i had the day off i thought i would clean the ICV as per instructions i found on this site.
Put it all back together and it idles at 1500 rpm when cold but as the engine warmed instead of dropping to a normal idle it starts pulsating between 12-1500 rpm constantly.
I checked i had put everything back as it came off and even replaced a couple of old looking vac pipes but still the same.
Thinking i did some damage cleaning the ICV i got a new one but it made no difference. Now i'm stuck and due to go on Hols Saturday and none of the garages can fit me in before then.
Anyone any ideas i can try before the family lynch me.
Cheers
Colin
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Re: Idle problems (Help)
Sounds to me like a vacuum leak. Also unmetered air - if you removed the hose from the airbox to the throttle body, is it correctly fitted and not leaking? MAF sensor connector properly fitted?
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From: beside the Great Salty Wetspot
Re: Idle problems (Help)
I would look at the ICV again.
I had a similar problem on a VW VR6 engine and it came down to some crud being lodged in the Idle Stabilizer Control Valve that wouldn't allow it to close completely, thus allowing air to free flow around the throttle plate. It reved as you described on about 3 second cycles when warmed up.
I had a similar problem on a VW VR6 engine and it came down to some crud being lodged in the Idle Stabilizer Control Valve that wouldn't allow it to close completely, thus allowing air to free flow around the throttle plate. It reved as you described on about 3 second cycles when warmed up.
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Re: Idle problems (Help)
I'm 99% sure the hose to the TB is connected ok.
I didn't touch the MAf i think. Not sure where it is to be honest.
Being a new ICV i don't think it is obstructed in any way.
Having searched the forum i found mention of the ECU needing to be re calibrated after ICV or similar change to match the stored settings to the new components.
Could that be the cause here ?
I didn't touch the MAf i think. Not sure where it is to be honest.
Being a new ICV i don't think it is obstructed in any way.
Having searched the forum i found mention of the ECU needing to be re calibrated after ICV or similar change to match the stored settings to the new components.
Could that be the cause here ?
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From: Redmond WA
Are you in the UK, I think you may not have a MAF, I think you might have a MAP sensor.
Sounds like a vacuum problem. You can cap the vacuum line coming out of the manifold to see if you have a leak or possibly put a vacuum gauge in the line to see if pressure is off.
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Re: Are you in the UK, I think you may not have a MAF, I think you might have a MAP sensor.
yes i am in the uk.
I took off a vacumm line that comes off the manifold near the ICV and it had quite a bit of suction so there is at least some vacuum there.
I will have to look deeper. I am half expecting to find something unplugged that i've missed but can't find any pictures that show a uk vacuum setup which seems quite different to the us.
thanks
I took off a vacumm line that comes off the manifold near the ICV and it had quite a bit of suction so there is at least some vacuum there.
I will have to look deeper. I am half expecting to find something unplugged that i've missed but can't find any pictures that show a uk vacuum setup which seems quite different to the us.
thanks
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From: Redmond WA
I think you have a changeover valve but no EGR.
So you can blank the vacuum off for a test.
The only thing its used for is the changeover valve and the heater/ AC flaps (goes thru firewall).The only other time I have seen this is when the throttle body gasket is leaking or the plenum/ throttle body rubber seal is not seated correctly allowing un metered air to bypass the MAF/ MAP. Is it possible you may have moved the plenum when you worked on the ICV. Is the temp sensor plugged in also.
The only thing its used for is the changeover valve and the heater/ AC flaps (goes thru firewall).The only other time I have seen this is when the throttle body gasket is leaking or the plenum/ throttle body rubber seal is not seated correctly allowing un metered air to bypass the MAF/ MAP. Is it possible you may have moved the plenum when you worked on the ICV. Is the temp sensor plugged in also.
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Re: I think you have a changeover valve but no EGR.
Thanks for that. I will try blanking the vacuum.
The rubber gasket between the plenum and the TB seems to be a sloppy fit so i'm going to try the phone cord mod to see if that helps.
Where is the temp sensor located ? Maybe that got knocked or something when i took the plenum off.
Thanks i think it's getting narrowed down.
Going to make a big effort to sort it tomorrow eve.
The rubber gasket between the plenum and the TB seems to be a sloppy fit so i'm going to try the phone cord mod to see if that helps.
Where is the temp sensor located ? Maybe that got knocked or something when i took the plenum off.
Thanks i think it's getting narrowed down.
Going to make a big effort to sort it tomorrow eve.
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Thread Starter
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Re: Thats almost under the ICV. you usually have to unplug it to get the ICV off.
<center><img src="http://www.polymoog.homecall.co.uk/test.JPG"></center><p>
Well i spent several hours tinkering but no luck.
A view other observations i made were that Idle is stable if high (1500rpm) for first minute or so then when the revs would normally drop as engine warms that's when it start pulsing.
The slightest touch on the throttle sends the revs racing up for a few seconds.
I replaced the Plenum to TB gasket and re checked every connection i could see. Engine temp reads fine so i'm guessing sensor is fine as their is only one sensor on mine.
Loading and unloading the engine stablises the idle for 10 seconds then is pulses again between 15 - 1800 rpm.
Looking like a dealer job i think. Wish i had a VAG
By the way disconnecting Icv makes no difference. It looks different to others i've seen (See Pic)
Well i spent several hours tinkering but no luck.
A view other observations i made were that Idle is stable if high (1500rpm) for first minute or so then when the revs would normally drop as engine warms that's when it start pulsing.
The slightest touch on the throttle sends the revs racing up for a few seconds.
I replaced the Plenum to TB gasket and re checked every connection i could see. Engine temp reads fine so i'm guessing sensor is fine as their is only one sensor on mine.
Loading and unloading the engine stablises the idle for 10 seconds then is pulses again between 15 - 1800 rpm.
Looking like a dealer job i think. Wish i had a VAG
By the way disconnecting Icv makes no difference. It looks different to others i've seen (See Pic)