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 Post subject: High idle
PostPosted: Sun Mar 19, 2017 5:43 pm 
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Hi members got high idling problems not had car long it Idles at 1100 then can jump to 2000 I have been told it's the idle control valve icv and that I might need air intake refresh what's your thoughts


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 Post subject: Re: High idle
PostPosted: Sun Mar 19, 2017 5:53 pm 
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Joined: Tue Nov 06, 2007 12:22 am
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Location: Stratford-upon-Avon
TIPEC membership: 4635
Idle valve is a suspect, but simple things to check before having to dive under intake are the throttle position switch (can check for click off idle, and electrically at the LH ECU connector) and the Temp II sensor (sits on right hand side of coolant bridge, with blue coloured connector.

If you get hold of cheap CD of workshop manual, there are detailed and logical tests for diagnosing running issues, requiring very simple tools.

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 Post subject: Re: High idle
PostPosted: Sun Mar 19, 2017 6:56 pm 
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I'm getting the click from the throtle movement not sure where this temp 11 sensor is


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 Post subject: Re: High idle
PostPosted: Sun Mar 19, 2017 7:05 pm 
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Is this ecu in passenger footwell all look good taken off then re connected Could there be a problem with this ecu ?


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 Post subject: Re: High idle
PostPosted: Sun Mar 19, 2017 11:14 pm 
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Sorry Terry should have asked what model and year is your car?

Always check the simple things first before you suspect ECU. Is the throttle butterfly closing fully? Crud or misdirected cable may be holding it open.

Most likely cause of high idle is still vacuum leak under intake.

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 Post subject: Re: High idle
PostPosted: Mon Mar 20, 2017 6:43 pm 
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Where is the butterfly situated and can this. Be seen visually


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 Post subject: Re: High idle
PostPosted: Mon Mar 20, 2017 7:06 pm 
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And the car is 1987 s4 auto thanks terry


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 Post subject: Re: High idle
PostPosted: Mon Mar 20, 2017 11:16 pm 
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Location: Stratford-upon-Avon
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Yes you can directly view throttle butterfly.

Remove top of airbox (undo clamp holding air injection hose), air filter, then lower air box (4 X 10mm nuts).

That exposes mass air sensor. Loosen the jubilee clip holding base of MAF to throttle body, and remove MAF. Don't forget it's attached by 5-way electrical connector. You can just pull this off to give you perfect view of butterfly. Does it close fully?

Before you check throttle, do a quick check for leaks around inlet manifold. With engine idling spray carb cleaner at various spots around manifold. If engine races at any point you have found area of vacuum leak.

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 Post subject: Re: High idle
PostPosted: Tue Mar 21, 2017 8:58 am 
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Thanks that's been very helpful will check this out also would thus cause It's idle speed to rise from 1100 to 2000 which it does as it sits idling sometimes


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 Post subject: Re: High idle
PostPosted: Tue Mar 21, 2017 11:57 am 
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Can you describe in more detail. Under what circumstances doe sit rise from 1100 (already very high) to 2000? How long does it stay at 2000? If it comes back down to 1100 how long does it stay there? Is the surging between 1100 and 2000 regular?

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 Post subject: Re: High idle
PostPosted: Tue Mar 21, 2017 6:14 pm 
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Hi just had 15 min with car it stated on 1500 then I turned off same again for 3-4 time then it went to 2400 for awhile gave it some throttle then it drops slowly to 2000 couldn't get it any lower than this even after on and off a few time so switched off what you think and like to say thanks for help


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 Post subject: Re: High idle
PostPosted: Tue Mar 21, 2017 7:49 pm 
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Gone bk to car 2 hours later now idling at 1200 ?


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 Post subject: Re: High idle
PostPosted: Wed Mar 22, 2017 1:09 am 
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Location: Stratford-upon-Avon
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Sounds like problem with ISV or the throttle switch.

The switch could be making click sound, but electrically switch not being made to signal idle throttle to LH ECU.

Easy to test with multimeter if you get the workshop manual for few quid on eBay or download free scans (Google for sources).

Or you could buy 'spanner' from JDS Porsche, but I think for your 87 the chip requires tweak to allow diagnostic to be plugged in and read signals. The JDS Porsche website will clarify if this is case and how to have the chip modified. The 'spanner' plugs in and can detect any fault in idle switch, temp sensor, basic ISV operation and others.

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Last edited by stratfordshark on Wed Mar 22, 2017 1:00 pm, edited 1 time in total.

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 Post subject: Re: High idle
PostPosted: Wed Mar 22, 2017 11:17 am 
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Thanks for reply will let you know how I go on cheers


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 Post subject: Re: High idle
PostPosted: Sun May 21, 2017 12:24 pm 
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Hi members still going thorough possible high idle issue when I get time that is but noticed today car idling @ 16oo ish for 4 or so seconds then drops to 11oo then straight back to 1600 this went on until engine warmed up then the electric fan kicked in and at that point it started to idle at 2000 revs any body got thoughts on this thanks terry


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