97 ZJ V8 JGC Wont idle when cold

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jamest - 21 Oct 2006 16:21 GMT

Greetings,

My 1997 ZJ will not idle when cold.

It happened 2 weeks ago and we cleaned the battery terminals, checked
grounds, and it all seemed good. After the cleaning truck ran fine. it
has about 75,000 miles on it an i take good care of it.

But this morning it was about 37 degrees, and it wont idle unless you
run it at about 1500 RPM.

After warming up , engine would idle normally. Have checked the
alternator
voltage, no codes appear other than the 55 code.

Any pointer appreciated, regards,

james

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billy ray - 21 Oct 2006 18:17 GMT

Excerpt from the '96 ZJ manual engine diagnosis 'Rough Idle"

http://i112.photobucket.com/albums/n171/Billy_Ray_2006/96ZJRoughIdle.jpg

While not required a thorough cleaning of the throttle body assemble, Idle
air passages, fuel system and injectors wouldn't hurt and only costs $12-$20
depending on brands and how thorough you need or want to clean.

> Greetings,
>
[quoted text clipped - 14 lines]
>
> james

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jamest - 25 Oct 2006 18:23 GMT

billy ray is the man!! - Thanks

$10 - Poured in a bottle of fuel system/injector cleaner into a full
tank of gas .
Seemd a little better...
$10 - Sprayed in TB cleaner and took it out for run on the freeway.
Better yet...
$80 - Picked up a new IAC Motor and changed it ( the old one was carbon
city ).
Sprayed a little TB cleaner in the IAC air passage and wiped out a lot
of carbon from there.
WOW..

It didnt run this smooth the day I bought it. Amazing, best $100 i ever
spent on it.

Thanks Again
jamest

> Excerpt from the '96 ZJ manual engine diagnosis 'Rough Idle"
>
[quoted text clipped - 22 lines]
> >
> > james

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Will Honea - 27 Oct 2006 10:45 GMT

You could probably have saved $80 by cleaning the old IAC and the
passages. As one last tweek, there is an idle bypass port with an
adjustment screw under one of those "tamper proof" covers. When I got
this Jeep, it was so plugged I had to look close to find the top of
the hole! That one took a long drill bit and nearly a can of cleaner
to open up - it runs all the way down into the manifold and you have
to remove the jet screw (count the turns!) to get all the way down
from the top of the throttle body.

> billy ray is the man!! - Thanks
>
[quoted text clipped - 41 lines]
> > >
> > > james

Signature

Will Honea

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jamest - 30 Oct 2006 14:05 GMT

Thanks,
I got the truck in 2000, its a 97, i figured a new IAC motor wasnt to
gross an indulgance.
How long a drill bit?

I will look up the Idle bypass port/Jet screw in the shop
manual/Alldata.
I am not a mechanic so things take a little longer:-)

thx,
james

> You could probably have saved $80 by cleaning the old IAC and the
> passages. As one last tweek, there is an idle bypass port with an
[quoted text clipped - 50 lines]
> > > >
> > > > james

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