Okay, I have been having this problem for some time now, and I'm hoping it
sounds familiar to somebody...

I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
runs fine all the way until I get to my destination, now the issue... if I
stop and shut it off for a few minutes (to run into a store or something)
when I get back in and start it again, I get an extreme hesitation and
serious RPM fluctuation at idle.

If I am sitting at idle, the RPM's fluctuate between 300 and 1000RPM's (at
300 it ALMOST stalls, but then it catches itself and the RPM's jump back up
to like 1000, it does this repeatedly)

When I put it in gear and go, the engine hesitates, to the point where it
seems like it will stall. The only way it will drive is if I floor the gas.
After a few minutes the problem works itself out, but until then, it is
virtually undriveable.

My first thought was that it was the TPS (so I replaced it), but the problem
is still there. Has anybody had a similar problem, and if so what fixed it?
I am pretty handy, doing 80% of the work on my Jeep, but with this issue it
seems like I could just keep replacing sensors until I'm in the poor house.

I am getting NO "Check Engine" light, so I don't even have that to start
diagnosing.

Thanks for any help in advance,

-John

 

jmorrison did pass the time by typing:
> Okay, I have been having this problem for some time now, and I'm hoping it
> sounds familiar to somebody...

It do.

> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
> runs fine all the way until I get to my destination, now the issue... if I
> stop and shut it off for a few minutes (to run into a store or something)
> when I get back in and start it again, I get an extreme hesitation and
> serious RPM fluctuation at idle.

"Hesitation after heat soak"

There is a TSB on this (can't find it right now, sorry)
but it calls for some insulation being put around injector #3 to
protect it from excessive engine heat that cause fuel to boil
in the rail. That vapor then causes all sorts of headaches
for the injectors till it clears. If you have an external
fuel filter it might also be needing replacement.

--
DougW

 

jmorrison did pass the time by typing:
> Okay, I have been having this problem for some time now, and I'm hoping it
> sounds familiar to somebody...

It do.

> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
> runs fine all the way until I get to my destination, now the issue... if I
> stop and shut it off for a few minutes (to run into a store or something)
> when I get back in and start it again, I get an extreme hesitation and
> serious RPM fluctuation at idle.

"Hesitation after heat soak"

There is a TSB on this (can't find it right now, sorry)
but it calls for some insulation being put around injector #3 to
protect it from excessive engine heat that cause fuel to boil
in the rail. That vapor then causes all sorts of headaches
for the injectors till it clears. If you have an external
fuel filter it might also be needing replacement.

--
DougW

 

jmorrison did pass the time by typing:
> Okay, I have been having this problem for some time now, and I'm hoping it
> sounds familiar to somebody...

It do.

> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts and
> runs fine all the way until I get to my destination, now the issue... if I
> stop and shut it off for a few minutes (to run into a store or something)
> when I get back in and start it again, I get an extreme hesitation and
> serious RPM fluctuation at idle.

"Hesitation after heat soak"

There is a TSB on this (can't find it right now, sorry)
but it calls for some insulation being put around injector #3 to
protect it from excessive engine heat that cause fuel to boil
in the rail. That vapor then causes all sorts of headaches
for the injectors till it clears. If you have an external
fuel filter it might also be needing replacement.

--
DougW

 

OK, that actually sounds promising. My only question(s). What do I use, and
what is the procedure for insulating the #3 injector? and Which injector is
#3?

-John


"DougW" <post.replies@invalid.address> wrote in message
news:q5_ad.41017$tU4.30486@okepread06...
> jmorrison did pass the time by typing:
>> Okay, I have been having this problem for some time now, and I'm hoping
>> it
>> sounds familiar to somebody...
>
> It do.
>
>> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts
>> and
>> runs fine all the way until I get to my destination, now the issue... if
>> I
>> stop and shut it off for a few minutes (to run into a store or something)
>> when I get back in and start it again, I get an extreme hesitation and
>> serious RPM fluctuation at idle.
>
> "Hesitation after heat soak"
>
> There is a TSB on this (can't find it right now, sorry)
> but it calls for some insulation being put around injector #3 to
> protect it from excessive engine heat that cause fuel to boil
> in the rail. That vapor then causes all sorts of headaches
> for the injectors till it clears. If you have an external
> fuel filter it might also be needing replacement.
>
> --
> DougW
>
>

 

OK, that actually sounds promising. My only question(s). What do I use, and
what is the procedure for insulating the #3 injector? and Which injector is
#3?

-John


"DougW" <post.replies@invalid.address> wrote in message
news:q5_ad.41017$tU4.30486@okepread06...
> jmorrison did pass the time by typing:
>> Okay, I have been having this problem for some time now, and I'm hoping
>> it
>> sounds familiar to somebody...
>
> It do.
>
>> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts
>> and
>> runs fine all the way until I get to my destination, now the issue... if
>> I
>> stop and shut it off for a few minutes (to run into a store or something)
>> when I get back in and start it again, I get an extreme hesitation and
>> serious RPM fluctuation at idle.
>
> "Hesitation after heat soak"
>
> There is a TSB on this (can't find it right now, sorry)
> but it calls for some insulation being put around injector #3 to
> protect it from excessive engine heat that cause fuel to boil
> in the rail. That vapor then causes all sorts of headaches
> for the injectors till it clears. If you have an external
> fuel filter it might also be needing replacement.
>
> --
> DougW
>
>

 

OK, that actually sounds promising. My only question(s). What do I use, and
what is the procedure for insulating the #3 injector? and Which injector is
#3?

-John


"DougW" <post.replies@invalid.address> wrote in message
news:q5_ad.41017$tU4.30486@okepread06...
> jmorrison did pass the time by typing:
>> Okay, I have been having this problem for some time now, and I'm hoping
>> it
>> sounds familiar to somebody...
>
> It do.
>
>> I have a 98 Wrangler 4.0 liter, if I start it from dead cold, it starts
>> and
>> runs fine all the way until I get to my destination, now the issue... if
>> I
>> stop and shut it off for a few minutes (to run into a store or something)
>> when I get back in and start it again, I get an extreme hesitation and
>> serious RPM fluctuation at idle.
>
> "Hesitation after heat soak"
>
> There is a TSB on this (can't find it right now, sorry)
> but it calls for some insulation being put around injector #3 to
> protect it from excessive engine heat that cause fuel to boil
> in the rail. That vapor then causes all sorts of headaches
> for the injectors till it clears. If you have an external
> fuel filter it might also be needing replacement.
>
> --
> DougW
>
>

 

jmorrison did pass the time by typing:
> OK, that actually sounds promising. My only question(s). What do I use, and
> what is the procedure for insulating the #3 injector? and Which injector is
> #3?

It's an insulating sleeve. You can get them at most racing parts stores.
http://tinyurl.com/59xd7
Problem is it requires taking the rail off and putting it back on. If you
do this, take it easy and put a bit of oil on the rings before putting the
rail back in. The bolts holding the rail to intake only go to about 17 ft.lbs
I always recommend new O rings each time the injectors come out. Just safer
that way.

You might be able to find an insulating wrap that can be secured with
simple plastic zip-ties. Zip ties can resist fairly high temps. That would
save on having to mess with the fuel rail.

#3 is third from the front.

Fan [ 1 2 3 4 5 6 ]

FWIW, I'm going to be doing my whole fuel system from the firewall.
Just as an experiment in heat reduction. The less heat into the engine
the better the performance.

--
DougW

 

jmorrison did pass the time by typing:
> OK, that actually sounds promising. My only question(s). What do I use, and
> what is the procedure for insulating the #3 injector? and Which injector is
> #3?

It's an insulating sleeve. You can get them at most racing parts stores.
http://tinyurl.com/59xd7
Problem is it requires taking the rail off and putting it back on. If you
do this, take it easy and put a bit of oil on the rings before putting the
rail back in. The bolts holding the rail to intake only go to about 17 ft.lbs
I always recommend new O rings each time the injectors come out. Just safer
that way.

You might be able to find an insulating wrap that can be secured with
simple plastic zip-ties. Zip ties can resist fairly high temps. That would
save on having to mess with the fuel rail.

#3 is third from the front.

Fan [ 1 2 3 4 5 6 ]

FWIW, I'm going to be doing my whole fuel system from the firewall.
Just as an experiment in heat reduction. The less heat into the engine
the better the performance.

--
DougW

 

jmorrison did pass the time by typing:
> OK, that actually sounds promising. My only question(s). What do I use, and
> what is the procedure for insulating the #3 injector? and Which injector is
> #3?

It's an insulating sleeve. You can get them at most racing parts stores.
http://tinyurl.com/59xd7
Problem is it requires taking the rail off and putting it back on. If you
do this, take it easy and put a bit of oil on the rings before putting the
rail back in. The bolts holding the rail to intake only go to about 17 ft.lbs
I always recommend new O rings each time the injectors come out. Just safer
that way.

You might be able to find an insulating wrap that can be secured with
simple plastic zip-ties. Zip ties can resist fairly high temps. That would
save on having to mess with the fuel rail.

#3 is third from the front.

Fan [ 1 2 3 4 5 6 ]

FWIW, I'm going to be doing my whole fuel system from the firewall.
Just as an experiment in heat reduction. The less heat into the engine
the better the performance.

--
DougW