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A wizard is never late...
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Discussion Starter #1
My fn2 had a service a couple of days ago this includes oil, filters, valve clearance, spark plugs and the pcv valve being changed. Now if I blip the throttle to around 2.5k revs it will drop then rev back up. Any ideas?

Thanks
 

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Check the intake pipe between the MAF and throttle body for splits, best to remove and get a proper look all around it,


How high does it rev?
 

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A wizard is never late...
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Discussion Starter #3
Only revs up to around 2k maybe 2.3k revs, and it dosnt do it every time. I was thinking maybe the rubber pipe to the pcv valve i is causing a vacuum leak?
 

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Living the dream!
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Does it need to go though the self learn process again, I once cleaned the throttle body on the FN2 and it was all over until I found the thread how to reset and relearn the ecu and once I had done this it run great again. All I did was remove all the black carbon build up on the inlet and it would not tick over very nice.
 

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It could be if its not tight, I've one pipe split because a jubilee was installed that nipped the pipe, always use a compression circlip


Easy way to test is whilst the engine is running pop the pcv hose off the manifold side and put your finger over it.


If the idle settles it's the hose
 

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A wizard is never late...
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Discussion Starter #6
Does it need to go though the self learn process again, I once cleaned the throttle body on the FN2 and it was all over until I found the thread how to reset and relearn the ecu and once I had done this it run great again. All I did was remove all the black carbon build up on the inlet and it would not tick over very nice.
It very well could be that, ill give it a few days to re learn and if it still revs up on its owni will visit the garage again

my only worry is if it is a vacuum leak would it mean the engine is running lean?
 

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A wizard is never late...
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793 Posts
Discussion Starter #7
It could be if its not tight, I've one pipe split because a jubilee was installed that nipped the pipe, always use a compression circlip


Easy way to test is whilst the engine is running pop the pcv hose off the manifold side and put your finger over it.


If the idle settles it's the hose
The only problem with trying this is its very hit and miss as to whether it revs up on its own. It did it twice today, the first I was thinking whats going on, and the second was a few hours later when I was moving it in the car park at work.

When I was driving home I tried to replicate it but it didnt do it. And when it does rev up it settles itself to idle after 3 or 4 seconds.
 

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Living the dream!
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It very well could be that, ill give it a few days to re learn and if it still revs up on its owni will visit the garage again

my only worry is if it is a vacuum leak would it mean the engine is running lean?
Find the guide on here and the follow it, I can't remember it all but do know you need to disconnect the battery to reset the ecu the follow a rev process to relearn
 

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Mine has also done it in stop start traffic, I was about to turn the key to shut it off in panic but then it settled itself back down to idle, it reached about 3000rpm on its own. Was quite alarming. Never done it since
 

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You could have a look at the Idle Air Control Valve (IACV) as it regulates hot idle. You can remove it and clean any crap out of it. Bleeding the coolant may help it too.
 

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A wizard is never late...
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Discussion Starter #14
dosn't really matter to much now anyway, i did it twice the day i posted this thread and hasn't done it since. still the suggestions were appreciated
 
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