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Yet another idle post.... #93177
April 27, 2001 05:35 am UTC
April 27, 2001 05:35 am UTC
Joined: Sep 2000
Posts: 61
Virginia, USA
G
Gary Singletary Offline OP
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Gary Singletary  Offline OP
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Joined: Sep 2000
Posts: 61
Virginia, USA
Ok I have read everything I possibly can find relating to idle issues and I'm stumped. Here's the situation...

The odd idle occurs only when cold and when the car is first started. Idle runs up to about 2500 rpms and will drop back to the 2000 range and then oscillate between 1800 and 2k until it warms up. The idle will only seem to oscillate when the clutch is let out and the car is put in neutral (or after coming to a stop after driving before it is warmed up). Once the car hits normal opperating temperature it idles perfect.

Here is what has been done:

1) Throttle body has been cleaned thoroughly.
2) BISS has new 0-ring
3) ISC checks out fine
4) Disabled the egr valve (pulled the vacuum lines and capped them)
5) Can't find any vacuum leaks.

One other point of interest. Even after the car is warm I can reproduce the surge by backing out the idle screw so that it idles at 1500ish.

I'm really running out of ideas at this point so any suggestions are appreciated.

Thanks in advance for the help,

Gary


91 Talon TSI FWD
Re: Yet another idle post.... #93178
April 27, 2001 06:16 am UTC
April 27, 2001 06:16 am UTC
Joined: Sep 2000
Posts: 61
Virginia, USA
G
Gary Singletary Offline OP
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Gary Singletary  Offline OP
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Joined: Sep 2000
Posts: 61
Virginia, USA
The car is a 1991 Talon Tsi FWD. Forgot to mention that in the first post.


91 Talon TSI FWD
Re: Yet another idle post.... #93179
April 27, 2001 11:58 am UTC
April 27, 2001 11:58 am UTC
Joined: Sep 1998
Posts: 7,944
Halifax, NS
Troy Jollimore Offline
Senior Member, with Far TOO Much Time on Their Hands
Troy Jollimore  Offline
Senior Member, with Far TOO Much Time on Their Hands
Joined: Sep 1998
Posts: 7,944
Halifax, NS
Damn! Another one! Mine is doing the same thing. I don't have much time to troubleshoot, though. It's happening to the early 1G's... Maybe it's an ECU Y2K issue? (:

Is your car misfiring? Running rich? Poor fuel economy? If you have an aftermarket boost gauge, what's the vacuum reading at idle? (Mine's 10in/hg.)

Re: Yet another idle post.... #93180
April 27, 2001 01:40 pm UTC
April 27, 2001 01:40 pm UTC
Joined: Jan 2001
Posts: 1,210
Toronto
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Chris Poe Offline
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Chris Poe  Offline
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Joined: Jan 2001
Posts: 1,210
Toronto
Try ECU caps if you didn't do them yet..
Also check your wastegate actuator to see if it s not keeping the flapper open by any chance.. that's one vacuum leak that took me a while to detect..


'92 FWD Talon TSI
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Re: Yet another idle post.... #93181
April 27, 2001 04:27 pm UTC
April 27, 2001 04:27 pm UTC
Joined: Sep 2000
Posts: 61
Virginia, USA
G
Gary Singletary Offline OP
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Gary Singletary  Offline OP
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Joined: Sep 2000
Posts: 61
Virginia, USA
I don't have a boost gauge hooked up to it yet so I'm not sure of the actual vacuum reading. The car is basically bone stock except for a k&n with an opened up air box. The car runs rich during the cycling stage but great once it's warmed up. I'm getting good gas mileage as well.


91 Talon TSI FWD
Re: Yet another idle post.... #93182
April 27, 2001 06:21 pm UTC
April 27, 2001 06:21 pm UTC
Joined: Nov 2000
Posts: 284
Halifax, NS, Canada
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Adrian Shields Offline
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Adrian Shields  Offline
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Joined: Nov 2000
Posts: 284
Halifax, NS, Canada
Could this idle phenomenom be the result of a bad gasket around the intake mani? When it warms up the leak reseals? Just thinking out loud here so bare with me. I have also heard of problems with the ISC (or IAC) in other cars... like Hyundai's, where the internals actually corode over time and result in unhindered air flow through the ISC. Since this seems to be an elusive prob, and seems to be happening on the older DSM's, I just thought that I would throw some thoughts out there for all to consider.
A.


===========
'97 TSi AWD

".... what the hell was that???"
Re: Yet another idle post.... #93183
April 27, 2001 09:51 pm UTC
April 27, 2001 09:51 pm UTC
Joined: Dec 2000
Posts: 1,986
North of T.O.
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Len Randall Offline
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Len Randall  Offline
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Joined: Dec 2000
Posts: 1,986
North of T.O.
you mentioned that you turned the idle down to 1500-ish when the car is warm and it surges...Thats exactly what is supposed to happen. The ecu is stepping the ISC up and down in its search for 750 RPM's.

Try grounding the timing connector and grounding terminal #10 of the diagnostic connector and check your idle. It should be 750. do all this with the engine warmed up.

If it aint close to 750, adjust your throttle cable, biss screw, but dont touch the TPS (its factory set).

------------------
Len...
92 Talon TSi AWD
89 2000 GTX


'92 Talon TSi AWD.

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