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Don

External


Since: Jun 17, 2007
Posts: 3



(Msg. 1) Posted: Tue Jun 26, 2007 9:56 pm
Post subject: Odd Idle Problem on '02 Tacoma
Archived from groups: alt>autos>toyota (more info?)
The truck is a 2002 Tacoma V-6 w/ 5-speed manual. Recently I have
noticed that as I am coming to a stop for a stop sign or traffic light
the idle RPM jumps up to about 1800. The clutch is pressed in, so there
is no load on the engine. The engine RPM remains elevated until the
vehicle comes to a complete stop. The RPM then drops to about 800. This
is so repeatable, that it almost seems like there is a wheel speed
sensor telling the engine the vehicle has come to a stop (maybe there is?!).

I did not notice this problem during the colder months. The hot weather
(SW Ohio) the past couple of weeks has aggravated the problem. It also
seems more pronounced with the A/C operating.

Aside from the remote possibility of an engine controller problem based
on wheel speed, I am thinking maybe some sort of vacuum problem. Or
possibly a flakey coolant temperature sensor. If this were a carbureted
engine I would think a float had a pin hole leak and had gas sloshing
around in it. But obviously this thing is EFI.

Anyone hear of this sort of problem? Any ideas what to look for?

Thanks!

Don

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mrsteveo

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Since: Jun 17, 2007
Posts: 70



(Msg. 2) Posted: Tue Jun 26, 2007 9:56 pm
Post subject: Re: Odd Idle Problem on '02 Tacoma [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
On Jun 26, 5:52 pm, Don wrote:
> The truck is a 2002 Tacoma V-6 w/ 5-speed manual. Recently I have
> noticed that as I am coming to a stop for a stop sign or traffic light
> the idle RPM jumps up to about 1800. The clutch is pressed in, so there
> is no load on the engine. The engine RPM remains elevated until the
> vehicle comes to a complete stop. The RPM then drops to about 800. This
> is so repeatable, that it almost seems like there is a wheel speed
> sensor telling the engine the vehicle has come to a stop (maybe there is?!).
>
> I did not notice this problem during the colder months. The hot weather
> (SW Ohio) the past couple of weeks has aggravated the problem. It also
> seems more pronounced with the A/C operating.
>
> Aside from the remote possibility of an engine controller problem based
> on wheel speed, I am thinking maybe some sort of vacuum problem. Or
> possibly a flakey coolant temperature sensor. If this were a carbureted
> engine I would think a float had a pin hole leak and had gas sloshing
> around in it. But obviously this thing is EFI.
>
> Anyone hear of this sort of problem? Any ideas what to look for?
>
> Thanks!
>
> Don

IAC valve?

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user

External


Since: Jan 11, 2007
Posts: 430



(Msg. 3) Posted: Wed Jun 27, 2007 8:54 am
Post subject: Re: Odd Idle Problem on '02 Tacoma [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
Don wrote:
>
>
> The truck is a 2002 Tacoma V-6 w/ 5-speed manual. Recently I have
> noticed that as I am coming to a stop for a stop sign or traffic light
> the idle RPM jumps up to about 1800. The clutch is pressed in, so there
> is no load on the engine. The engine RPM remains elevated until the
> vehicle comes to a complete stop. The RPM then drops to about 800. This
> is so repeatable, that it almost seems like there is a wheel speed
> sensor telling the engine the vehicle has come to a stop (maybe there
> is?!).
>
> I did not notice this problem during the colder months. The hot weather
> (SW Ohio) the past couple of weeks has aggravated the problem. It also
> seems more pronounced with the A/C operating.
>
> Aside from the remote possibility of an engine controller problem based
> on wheel speed, I am thinking maybe some sort of vacuum problem. Or
> possibly a flakey coolant temperature sensor. If this were a carbureted
> engine I would think a float had a pin hole leak and had gas sloshing
> around in it. But obviously this thing is EFI.
>
> Anyone hear of this sort of problem? Any ideas what to look for?
>
> Thanks!
>
> Don
Is the service engine light illuminated? Scan the computer for any set
codes even the intermittant ones. I would think along the lines of the
others in checking the idle air component. Also check the coolant temp
sensor.
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Don6

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Since: Jun 30, 2004
Posts: 7



(Msg. 4) Posted: Wed Jun 27, 2007 10:55 pm
Post subject: Re: Odd Idle Problem on '02 Tacoma UPDATE [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
First off, "Thanks!" to everyone's suggestions!

I spent a little time under the hood before a thunderstorm chased me in, so
only have partial answers:


1) The engine check light is not "ON". Could there me useful codes even
though the light is not "ON"? I think I know someone who has an ODBC test
set, but not sure if it would read Toyota specific service codes.

2) The throttle linkage is connected to the pedal via a mechanical cable.
It appears to move smoothly with no binding and sticking.

3) Started trying to figure out the IAC stuff using the manual when the
rain came, so I will pick up there Thursday or Friday.

4) Once I come to a complete stop and the RPM comes down to normal I can
punch the accelerator and the RPM returns to normal (~800 RPM)

5) If I coast (out of gear, foot off the accelerator) the RPM will
occasionally bounce around between 800 and 1800 RPM.


That's about it for now!

Thanks again for the hints!

Don







"Don" wrote in message

>
>
> The truck is a 2002 Tacoma V-6 w/ 5-speed manual. Recently I have
> noticed that as I am coming to a stop for a stop sign or traffic light
> the idle RPM jumps up to about 1800. The clutch is pressed in, so there
> is no load on the engine. The engine RPM remains elevated until the
> vehicle comes to a complete stop. The RPM then drops to about 800. This
> is so repeatable, that it almost seems like there is a wheel speed
> sensor telling the engine the vehicle has come to a stop (maybe there
is?!).
>
> I did not notice this problem during the colder months. The hot weather
> (SW Ohio) the past couple of weeks has aggravated the problem. It also
> seems more pronounced with the A/C operating.
>
> Aside from the remote possibility of an engine controller problem based
> on wheel speed, I am thinking maybe some sort of vacuum problem. Or
> possibly a flakey coolant temperature sensor. If this were a carbureted
> engine I would think a float had a pin hole leak and had gas sloshing
> around in it. But obviously this thing is EFI.
>
> Anyone hear of this sort of problem? Any ideas what to look for?
>
> Thanks!
>
> Don
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Ray O

External


Since: Jun 02, 2006
Posts: 4627



(Msg. 5) Posted: Sun Jul 01, 2007 1:47 am
Post subject: Re: Odd Idle Problem on '02 Tacoma [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
"Don" wrote in message

>
>
> The truck is a 2002 Tacoma V-6 w/ 5-speed manual. Recently I have noticed
> that as I am coming to a stop for a stop sign or traffic light the idle
> RPM jumps up to about 1800. The clutch is pressed in, so there is no load
> on the engine. The engine RPM remains elevated until the vehicle comes to
> a complete stop. The RPM then drops to about 800. This is so repeatable,
> that it almost seems like there is a wheel speed sensor telling the engine
> the vehicle has come to a stop (maybe there is?!).
>
> I did not notice this problem during the colder months. The hot weather
> (SW Ohio) the past couple of weeks has aggravated the problem. It also
> seems more pronounced with the A/C operating.
>
> Aside from the remote possibility of an engine controller problem based on
> wheel speed, I am thinking maybe some sort of vacuum problem. Or possibly
> a flakey coolant temperature sensor. If this were a carbureted engine I
> would think a float had a pin hole leak and had gas sloshing around in it.
> But obviously this thing is EFI.
>
> Anyone hear of this sort of problem? Any ideas what to look for?
>
> Thanks!
>
> Don

I would check what qslm suggests and leave it at that. Since the condition
is so repeatable, my guess is that it is a normal emissions control
function. The idle-up will be more pronounced with the AC operating because
of the AC idle-up function.

I doubt if it is a problem because vacuum problems generally cause rough
idle or poor performance. You can check vacuum with a vacuum gauge to make
sure there is no vacuum leak. Also check the intake tube between the air
filter housing and throttle body for holes, gaps, or cracks.
--

Ray O
(correct punctuation to reply)
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Don

External


Since: Jun 17, 2007
Posts: 3



(Msg. 6) Posted: Sun Jul 01, 2007 10:57 pm
Post subject: Re: Odd Idle Problem on '02 Tacoma - Another Update [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
Looks like the problem is with the IAC valve (or something attached to
it). I friend of mine has a scan tool and checked for codes. We drove
around for a while and nothing. He suggested disconnecting the IAC.
While I got a check engine light, the idle was perfect.

Based on some searching, it appears that it is somewhat common for the
IAC to go bad. Once I get a little more time, I am going to do some
more testing to try to confirm it is the IAC itself. Then it will
likely be a matter of springing for one and putting it in.

Thanks for the help!

Don


Don wrote:
>
>
> The truck is a 2002 Tacoma V-6 w/ 5-speed manual. Recently I have
> noticed that as I am coming to a stop for a stop sign or traffic light
> the idle RPM jumps up to about 1800. The clutch is pressed in, so there
> is no load on the engine. The engine RPM remains elevated until the
> vehicle comes to a complete stop. The RPM then drops to about 800. This
> is so repeatable, that it almost seems like there is a wheel speed
> sensor telling the engine the vehicle has come to a stop (maybe there
> is?!).
>
> I did not notice this problem during the colder months. The hot weather
> (SW Ohio) the past couple of weeks has aggravated the problem. It also
> seems more pronounced with the A/C operating.
>
> Aside from the remote possibility of an engine controller problem based
> on wheel speed, I am thinking maybe some sort of vacuum problem. Or
> possibly a flakey coolant temperature sensor. If this were a carbureted
> engine I would think a float had a pin hole leak and had gas sloshing
> around in it. But obviously this thing is EFI.
>
> Anyone hear of this sort of problem? Any ideas what to look for?
>
> Thanks!
>
> Don
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Ray O

External


Since: Jun 02, 2006
Posts: 4627



(Msg. 7) Posted: Sun Jul 01, 2007 10:57 pm
Post subject: Re: Odd Idle Problem on '02 Tacoma - Another Update [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
"Don" wrote in message

> Looks like the problem is with the IAC valve (or something attached to
> it). I friend of mine has a scan tool and checked for codes. We drove
> around for a while and nothing. He suggested disconnecting the IAC. While
> I got a check engine light, the idle was perfect.
>
> Based on some searching, it appears that it is somewhat common for the IAC
> to go bad. Once I get a little more time, I am going to do some more
> testing to try to confirm it is the IAC itself. Then it will likely be a
> matter of springing for one and putting it in.
>
> Thanks for the help!
>
> Don
>

Before you go out any buy a new IAC, try cleaning the old one with
carburetor cleaner first.
--

Ray O
(correct punctuation to reply)
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