Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

Hi:



I'm hoping some of you XJ fans can offer some suggestions on a problem that
just happened to me today for the first time.



First of all, the specs: 1989 Cherokee LTD (XJ), inline 6 cylinder, 4 litre,
with 150k Km's (ie: relatively low mileage, or more accurately 'kilometerage'
for the year).



I drove to Costco this morning, about a 15 km drive. Everything was fine on
the drive there but when I started the truck up to come home (1/2 hour
later), it was idling roughly and would stumble quite a bit while driving
(but it didn't stall) - it felt like it wasn't running on all cylinders. I
did make it home where I did a thorough once over of under hood wires and
hoses and couldn't see any obvious problems.



The last time I drove the jeep was about 3 weeks ago. It's rained a lot
since the so it could be that some water has got into the gas tank, but I've
lived here in Vancouver for over 20 years and the constant rain we get for 9
months of the year has never been a problem before.



My XJ has never failed to start since I purchased in new in 89, however
after it was a year old, it began to take a bit of cranking (say 20 seconds)
to get it going. It's been that way ever since. I took it to several
dealers all of who said that a bit of cranking was normal. Since it wasn't
normal when the jeep was new, I've often wondered if the CPS was faulty, but
in all the reading that I've done, a faulty CPS seems to manifest itself in
intermittent start failures and I've never had a start failure.



Anyone have any suggestions on likely candidate for the source of my
trouble? Thanks for any advice.



Regards,

Dave


--

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

NT wrote:

> First of all, the specs: 1989 Cherokee LTD (XJ), inline 6 cylinder, 4
> litre, with 150k Km's (ie: relatively low mileage, or more accurately
> 'kilometerage' for the year).

> I drove to Costco this morning, about a 15 km drive. Everything was
> fine on the drive there but when I started the truck up to come home
> (1/2 hour later), it was idling roughly and would stumble quite a bit
> while driving (but it didn't stall) - it felt like it wasn't running
> on all cylinders. I did make it home where I did a thorough once
> over of under hood wires and hoses and couldn't see any obvious
> problems.

How long has it been since you changed the fuel filter?

--
DougW

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

NT wrote:

> First of all, the specs: 1989 Cherokee LTD (XJ), inline 6 cylinder, 4
> litre, with 150k Km's (ie: relatively low mileage, or more accurately
> 'kilometerage' for the year).

> I drove to Costco this morning, about a 15 km drive. Everything was
> fine on the drive there but when I started the truck up to come home
> (1/2 hour later), it was idling roughly and would stumble quite a bit
> while driving (but it didn't stall) - it felt like it wasn't running
> on all cylinders. I did make it home where I did a thorough once
> over of under hood wires and hoses and couldn't see any obvious
> problems.

How long has it been since you changed the fuel filter?

--
DougW

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

NT wrote:

> First of all, the specs: 1989 Cherokee LTD (XJ), inline 6 cylinder, 4
> litre, with 150k Km's (ie: relatively low mileage, or more accurately
> 'kilometerage' for the year).

> I drove to Costco this morning, about a 15 km drive. Everything was
> fine on the drive there but when I started the truck up to come home
> (1/2 hour later), it was idling roughly and would stumble quite a bit
> while driving (but it didn't stall) - it felt like it wasn't running
> on all cylinders. I did make it home where I did a thorough once
> over of under hood wires and hoses and couldn't see any obvious
> problems.

How long has it been since you changed the fuel filter?

--
DougW

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

Hi Doug:

Thanks for your response. It's been several years, but not that many Km's
ago - probably about 45k Km's.

I wouldn't expect a fuel filter to be fine, then 30 minutes later be clogged
enough to start causing problems. I don't know - can say I've ever had a
fuel filter problem before (that I knew of).

--

"DougW" <post.replies@invalid.address> wrote in message
news:aIa1h.232$Jt3.32@newsfe16.lga...
> NT wrote:
>
>> First of all, the specs: 1989 Cherokee LTD (XJ), inline 6 cylinder, 4
>> litre, with 150k Km's (ie: relatively low mileage, or more accurately
>> 'kilometerage' for the year).
>
>> I drove to Costco this morning, about a 15 km drive. Everything was
>> fine on the drive there but when I started the truck up to come home
>> (1/2 hour later), it was idling roughly and would stumble quite a bit
>> while driving (but it didn't stall) - it felt like it wasn't running
>> on all cylinders. I did make it home where I did a thorough once
>> over of under hood wires and hoses and couldn't see any obvious
>> problems.
>
> How long has it been since you changed the fuel filter?
>
> --
> DougW
>

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

Hi Doug:

Thanks for your response. It's been several years, but not that many Km's
ago - probably about 45k Km's.

I wouldn't expect a fuel filter to be fine, then 30 minutes later be clogged
enough to start causing problems. I don't know - can say I've ever had a
fuel filter problem before (that I knew of).

--

"DougW" <post.replies@invalid.address> wrote in message
news:aIa1h.232$Jt3.32@newsfe16.lga...
> NT wrote:
>
>> First of all, the specs: 1989 Cherokee LTD (XJ), inline 6 cylinder, 4
>> litre, with 150k Km's (ie: relatively low mileage, or more accurately
>> 'kilometerage' for the year).
>
>> I drove to Costco this morning, about a 15 km drive. Everything was
>> fine on the drive there but when I started the truck up to come home
>> (1/2 hour later), it was idling roughly and would stumble quite a bit
>> while driving (but it didn't stall) - it felt like it wasn't running
>> on all cylinders. I did make it home where I did a thorough once
>> over of under hood wires and hoses and couldn't see any obvious
>> problems.
>
> How long has it been since you changed the fuel filter?
>
> --
> DougW
>

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

Hi Doug:

Thanks for your response. It's been several years, but not that many Km's
ago - probably about 45k Km's.

I wouldn't expect a fuel filter to be fine, then 30 minutes later be clogged
enough to start causing problems. I don't know - can say I've ever had a
fuel filter problem before (that I knew of).

--

"DougW" <post.replies@invalid.address> wrote in message
news:aIa1h.232$Jt3.32@newsfe16.lga...
> NT wrote:
>
>> First of all, the specs: 1989 Cherokee LTD (XJ), inline 6 cylinder, 4
>> litre, with 150k Km's (ie: relatively low mileage, or more accurately
>> 'kilometerage' for the year).
>
>> I drove to Costco this morning, about a 15 km drive. Everything was
>> fine on the drive there but when I started the truck up to come home
>> (1/2 hour later), it was idling roughly and would stumble quite a bit
>> while driving (but it didn't stall) - it felt like it wasn't running
>> on all cylinders. I did make it home where I did a thorough once
>> over of under hood wires and hoses and couldn't see any obvious
>> problems.
>
> How long has it been since you changed the fuel filter?
>
> --
> DougW
>

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

NT wrote:
> Hi Doug:
>
> Thanks for your response. It's been several years, but not that many
> Km's ago - probably about 45k Km's.
>
> I wouldn't expect a fuel filter to be fine, then 30 minutes later be
> clogged enough to start causing problems. I don't know - can say
> I've ever had a fuel filter problem before (that I knew of).

They do that. The filter will pass fuel at the proper rate up till
the point it gets too clogged. Usually it shows as a lack of power
or pinging under load/full throttle.
http://revbeergoggles.com/badgas/

I change my filter every 10,000 miles and it's astonishing what junk
can come out of it.

The other possibility is heat-soak related. That can be a failing
sensor or even the coil. When my coil died the engine would run
when cold but would sputter and buck when restarted warm. Finally
it just stopped. Oddly, the coil ohmed out just fine. But I threw
another coil on simply because I couldn't find another reason
why it wouldn't start.

Worst off if you get a new coil, you have a spare. :)

The CPS sensor can also exhibit heat related failure. At least on
my ZJ it's on the exhaust side of the engine just behind the downpipe.
The only real way to know if that sensor is having problems is with
a scope.

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

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

NT wrote:
> Hi Doug:
>
> Thanks for your response. It's been several years, but not that many
> Km's ago - probably about 45k Km's.
>
> I wouldn't expect a fuel filter to be fine, then 30 minutes later be
> clogged enough to start causing problems. I don't know - can say
> I've ever had a fuel filter problem before (that I knew of).

They do that. The filter will pass fuel at the proper rate up till
the point it gets too clogged. Usually it shows as a lack of power
or pinging under load/full throttle.
http://revbeergoggles.com/badgas/

I change my filter every 10,000 miles and it's astonishing what junk
can come out of it.

The other possibility is heat-soak related. That can be a failing
sensor or even the coil. When my coil died the engine would run
when cold but would sputter and buck when restarted warm. Finally
it just stopped. Oddly, the coil ohmed out just fine. But I threw
another coil on simply because I couldn't find another reason
why it wouldn't start.

Worst off if you get a new coil, you have a spare. :)

The CPS sensor can also exhibit heat related failure. At least on
my ZJ it's on the exhaust side of the engine just behind the downpipe.
The only real way to know if that sensor is having problems is with
a scope.

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

Re: Help with 1989 Cherokee XJ LTD rough idle and acceleration
 

NT wrote:
> Hi Doug:
>
> Thanks for your response. It's been several years, but not that many
> Km's ago - probably about 45k Km's.
>
> I wouldn't expect a fuel filter to be fine, then 30 minutes later be
> clogged enough to start causing problems. I don't know - can say
> I've ever had a fuel filter problem before (that I knew of).

They do that. The filter will pass fuel at the proper rate up till
the point it gets too clogged. Usually it shows as a lack of power
or pinging under load/full throttle.
http://revbeergoggles.com/badgas/

I change my filter every 10,000 miles and it's astonishing what junk
can come out of it.

The other possibility is heat-soak related. That can be a failing
sensor or even the coil. When my coil died the engine would run
when cold but would sputter and buck when restarted warm. Finally
it just stopped. Oddly, the coil ohmed out just fine. But I threw
another coil on simply because I couldn't find another reason
why it wouldn't start.

Worst off if you get a new coil, you have a spare. :)

The CPS sensor can also exhibit heat related failure. At least on
my ZJ it's on the exhaust side of the engine just behind the downpipe.
The only real way to know if that sensor is having problems is with
a scope.

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