[V8] Idle speed too high

Dave Saad dsaad at icehouse.net
Tue Jan 20 06:23:13 PST 2009

Sounds like a vacuum leak to me...


On Jan 19, 2009, at 11:03 PM, Ed Kellock wrote:

> I used 3-in-1 oil to lubricate.  I did not disassemble anything.
> Prior to that I used Liquid Wrench to clean the area and work the  
> movement
> to free it up real good.  It did not feel stiff or sluggish in any  
> way to
> begin with.
> Actually, I forgot to put the 3-in-1 oil on the front pivot of the
> throttle linkage before reinstalling the throttle body.
> The action of the throttle is and was very smooth and I am very sure  
> that
> the mechanical action is not the problem.  On general principal, I do
> believe there is more I can do to ensure its longevity, etc. but for  
> now,
> I really believe there is another issue affecting idle speed.
> It may be time to do some parts swapping.  The 1990 V8q came home this
> evening with a misfire so it will be staying with me tomorrow while  
> the 93
> carries the GF to work.  While I'm at it, I might as well start  
> swapping
> parts around between the 90 and 91.
> On the 90 V8, I recently replaced spark plugs and distributor caps  
> due to
> long cranking times when cold.  I did not have rotors at the time.   
> I used
> Autolite plugs, but I went up one step... I'm not sure if they were
> platinum, but I know they weren't the iridium.  I recall some  
> discussion
> about Autolites failing, the center electrode physically separating  
> from
> the rest, so I will check for that.  I'll start by trying to isolate  
> which
> cylinder is not firing and go from there.  This weekend I did a tranny
> drain/refill as well as replaced the coolant reservoir.  It ran fine
> afterward and again yesterday for a trip to the market.  Seems the  
> misfire
> was first present this morning.  Anyway...
> Ed
>> -----Original Message-----
>> From: Ingo Rautenberg [mailto:ingo.rautenberg at gmail.com]
>> Sent: Monday, January 19, 2009 8:51 PM
>> To: Ed Kellock
>> Cc: 'q - V8'
>> Subject: Re: [V8] Idle speed too high
>> Hmm.  When you say that you lubricated the throttle rod/pivot
>> assembly -- did you do front and back?  By front I mean at the
>> bearing you can't see but can feel when you remove the throttle
>> body.  This one really tends to dry up and should be lubed at the
>> least or (preferably) replaced.
>> Ingo
>> On Jan 19, 2009, at 10:29 PM, Ed Kellock wrote:
>>> Patient is my 91 5spd.  Idle speed is consistently a little too
>>> high, like
>>> 1100.  Here's what I've done....
>>> -removed/cleaned ISV
>>> -adjusted TPS
>>> -opened up and cleaned throttle butterflies directly -lubricated
>>> throttle rod/pivot assembly (it was and is smooth and
>>> returns
>>> to stop solidly)
>>> -went through everything again checking for vacuum leaks
>>> -checked cruise control for adjustment etc., no interference
>>> Initially I could lower it some by pushing down on the small lever
>>> at the
>>> front and I found that I had the TPS adjusted so that it was
>>> causing the
>>> throttle to hang open a bit.  I loosed the TPS, pushed down on the
>>> level,
>>> backed the TPS off a little tiny bit more and snugged it down.  I
>>> confirmed it still returns to closed throttle position (click).
>>> The last thing I did was unplug the ISV and start the engine.  The
>>> idle
>>> seemed right for a moment but then slowly climbed up to 1100.  It
>>> seems
>>> like it's ECU or something.
>>> When I turn the engine off, there's a clack in the passenger side
>>> fender
>>> well.  I know there's some emmissions shite in there, a reservoir
>>> and a
>>> valve of some kind, but I don't know what it should/shouldn't do.
>>> I am
>>> fairly sure I've never heard a clack from that area ever on any of
>>> my V8s.
>>> Maybe I just never noticed.
>>> Thanks,
>>> Ed
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