91 XJ: idling problems

I've got a 91 XJ. When cold it has problems idling (whether in gear or not).
After about 15 minutes the idling problem disappears. Last time I checked
the plugs, the frontmost plug was in bad shape the electrode was nearly worn
away, I managed to gap it, but I really should've replaced it. Could this be
the problem?

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Doug did pass the time by typing:
> I've got a 91 XJ. When cold it has problems idling (whether in gear or not).
> After about 15 minutes the idling problem disappears. Last time I checked
> the plugs, the frontmost plug was in bad shape the electrode was nearly worn
> away, I managed to gap it, but I really should've replaced it. Could this be
> the problem?

Yep. That and carboning up #1, and helping to clog your cat.

Saving a plug could burn out your coil. Go get some Autolite plugs and pop
em in.

Could also be the throttle body idle air passage.
http://members.cox.net/wilsond/tb/tb.html

--
-- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
Banks Header - and BEER, in the fridge!

I wish I knew how that one plug got so eroded while the rest looked great. I
guess I'll replace it tomorrow. Autolite's your recommendation then? The
other plugs looked great so I shouldn't have to replace them.

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"DougW" > wrote in message
news:EIbhe.8737$Ri4.7057@okepread07...
> Doug did pass the time by typing:
>> I've got a 91 XJ. When cold it has problems idling (whether in gear or
>> not).
>> After about 15 minutes the idling problem disappears. Last time I checked
>> the plugs, the frontmost plug was in bad shape the electrode was nearly
>> worn
>> away, I managed to gap it, but I really should've replaced it. Could this
>> be
>> the problem?
>
> Yep. That and carboning up #1, and helping to clog your cat.
>
> Saving a plug could burn out your coil. Go get some Autolite plugs and
> pop
> em in.
>
> Could also be the throttle body idle air passage.
> http://members.cox.net/wilsond/tb/tb.html
>
> --
> -- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
> HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
> Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
> Banks Header - and BEER, in the fridge!
>

How many miles are on the plugs? If more than 30K, I would dump them
all.

I also prefer Champion plugs, but that is just me.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Doug wrote:
>
> I wish I knew how that one plug got so eroded while the rest looked great. I
> guess I'll replace it tomorrow. Autolite's your recommendation then? The
> other plugs looked great so I shouldn't have to replace them.
>
> --
> Remove nospam to email
> "DougW" > wrote in message
> news:EIbhe.8737$Ri4.7057@okepread07...
> > Doug did pass the time by typing:
> >> I've got a 91 XJ. When cold it has problems idling (whether in gear or
> >> not).
> >> After about 15 minutes the idling problem disappears. Last time I checked
> >> the plugs, the frontmost plug was in bad shape the electrode was nearly
> >> worn
> >> away, I managed to gap it, but I really should've replaced it. Could this
> >> be
> >> the problem?
> >
> > Yep. That and carboning up #1, and helping to clog your cat.
> >
> > Saving a plug could burn out your coil. Go get some Autolite plugs and
> > pop
> > em in.
> >
> > Could also be the throttle body idle air passage.
> > http://members.cox.net/wilsond/tb/tb.html
> >
> > --
> > -- DougW -- 93 ZJ 4.0 http://members.cox.net/wilsond
> > HESCO Supercharger - 300W IASCA Stereo - Edelbrock IAS Shocks
> > Gibson Exhaust - rear DCpower - custom gauge install - Stillen Rotors
> > Banks Header - and BEER, in the fridge!
> >

Doug did pass the time by typing:
> I wish I knew how that one plug got so eroded while the rest looked great. I
> guess I'll replace it tomorrow. Autolite's your recommendation then? The
> other plugs looked great so I shouldn't have to replace them.

Sometimes plugs are defective from the factory. The other thing is
plugs for 1 and 6 get the least amount of cooling from the water jacket.
What will cause the electrodes to erode is pre-ignition/pinging and that
can be caused by hot spots, carbon buildup, faulty injector. I'm betting
that the sparkplug was shot and it was causing the problem.

If you replace plugs you should replace them all. They are cheap.
Getting at #1 will require a swivel socket. And use a torque wrench,
plugs go to 25-30 ft.lbs.

Depending on how old your rotor, cap, and wires are you should replace
those too. If you need a reference here is a ref.
http://members.cox.net/wilsond/Fixes...cs.html#firing

I like autolite but there are others including Champion. The splitfire/iridium/
multisparkomaticmakeyoursledarocket plugs are junk.

--
DougW

The plug wasn't number one, it was number two (counting from the front of
the vehicle, in ascending order). This plug was the ONLY plug that was
different from the rest. It was a Champion 4412 and 1/4 (at least) of the
electrode was completely worn away. The other plugs are all Autolite 985's.
I'm thinking the stealership had something to do with this, because I
normally use Autolite 985's. I'm wondering if they might have put in a used
Champion 4412 for some bizarre reason. The SUV starts, but I'll have to see
if this clears up my idling problem. If not, it's on to the TPS and throttle
body for some cleaning.

Thanks for the help everyone...

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"Doug" > wrote in message
...
> I've got a 91 XJ. When cold it has problems idling (whether in gear or
> not). After about 15 minutes the idling problem disappears. Last time I
> checked the plugs, the frontmost plug was in bad shape the electrode was
> nearly worn away, I managed to gap it, but I really should've replaced it.
> Could this be the problem?
>
> --
> Remove nospam to email
>

> SUV starts, but I'll have to see if this clears up my idling problem. If
> not, it's on to the TPS and throttle
> body for some cleaning.
>
> Thanks for the help everyone...

I know your problem now... Its MAD at you because you called it a SUV, It's
a JeeP NOT an SUV ..

Snow...

Snow proclaimed:

>>SUV starts, but I'll have to see if this clears up my idling problem. If
>>not, it's on to the TPS and throttle
>>body for some cleaning.
>>
>>Thanks for the help everyone...
>
>
> I know your problem now... Its MAD at you because you called it a SUV, It's
> a JeeP NOT an SUV ..
>

Give the guy some time. I have a coworker who bought a new jeep and
wouldn't even drive the thing in the rain for a month or so. Now he
is complaining because he bunged up a skid plate taking a "shortcut"
at too high a speed last weekend.