HELP 98 Cherokee "miss"

When driving at road speed (35-60), particularly when the engine is
not warmed up, I recently developed a "miss", a stutter or hesitation,
when applying the gas. I thought it was an engine miss at first and
replaced plugs, rotor, cap, etc. Engine runs fine. Now I think the
"miss" may be in the transmission. If I'm driving and give it a bit
of gas it feels like the engine is miss firing, but I think it is the
transmission skipping. If I punch it down enough to drop to a lower
gear, the stutter stops and engine sounds fine. Once everything warms
up, everyhting seems to run well.

So, could it be a punch-down switch on the tranny or something in the
transmission that is acting up? Anyone else ever have this occur? Of
course, I hope it is something simple, not a major transmission
problem.

Mike

mbyoh wrote:
> When driving at road speed (35-60), particularly when the engine is
> not warmed up, I recently developed a "miss", a stutter or hesitation,
> when applying the gas. I thought it was an engine miss at first and
> replaced plugs, rotor, cap, etc. Engine runs fine. Now I think the
> "miss" may be in the transmission. If I'm driving and give it a bit
> of gas it feels like the engine is miss firing, but I think it is the
> transmission skipping. If I punch it down enough to drop to a lower
> gear, the stutter stops and engine sounds fine. Once everything warms
> up, everyhting seems to run well.
>
> So, could it be a punch-down switch on the tranny or something in the
> transmission that is acting up? Anyone else ever have this occur? Of
> course, I hope it is something simple, not a major transmission
> problem.

Engine RPM related. That can be any number of things.

The problem in the 98 is they got rid of the abiltiy to pull codes
with the key on-off-on-off-on trick. It takes a diagnostic tool.

Here is a laundry list.

Bad or failing coil
-can cause miss particurally at higher rpm

Bad connectors to the CPS (crankshaft position sensor)
-usually when hot, but when the CPS fails your jeep stops running

Bad O2 sensor
- Shows up as bad MPG and decrease in power as the engine runs too rich
- will also show up as excess carbon on the plugs

Dirty IAP (idle air passage)
- rough idle usually is the first indication

Clogged fuel filter
- usually shows up as lack of higher rpm power but can cause lean
pinging at full throttle.

Since you already did most of the ignition, I'd suggest start by cleaning
the connectors (watch you don't get contact cleaner on the paint and use
a good dilectric grease to keep the water out.

And clean the idle air passage.
http://revbeergoggles.com/tb/tb.html


The other thing to do is reset the Jeeps brain. Just pull the battery
for 10-15 min. Amazing what that can clear up sometimes.


--
-- 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!

"DougW" > wrote in message
news
> mbyoh wrote:
>> When driving at road speed (35-60), particularly when the engine is
>> not warmed up, I recently developed a "miss", a stutter or hesitation,
>> when applying the gas. I thought it was an engine miss at first and
>> replaced plugs, rotor, cap, etc. Engine runs fine. Now I think the
>> "miss" may be in the transmission. If I'm driving and give it a bit
>> of gas it feels like the engine is miss firing, but I think it is the
>> transmission skipping. If I punch it down enough to drop to a lower
>> gear, the stutter stops and engine sounds fine. Once everything warms
>> up, everyhting seems to run well.
>>
>> So, could it be a punch-down switch on the tranny or something in the
>> transmission that is acting up? Anyone else ever have this occur? Of
>> course, I hope it is something simple, not a major transmission
>> problem.
>
> Engine RPM related. That can be any number of things.
>
> The problem in the 98 is they got rid of the abiltiy to pull codes
> with the key on-off-on-off-on trick. It takes a diagnostic tool.
>
> Here is a laundry list.
>
> Bad or failing coil
> -can cause miss particurally at higher rpm
>
> Bad connectors to the CPS (crankshaft position sensor)
> -usually when hot, but when the CPS fails your jeep stops running
>
> Bad O2 sensor
> - Shows up as bad MPG and decrease in power as the engine runs too rich
> - will also show up as excess carbon on the plugs
>
> Dirty IAP (idle air passage)
> - rough idle usually is the first indication
>
> Clogged fuel filter
> - usually shows up as lack of higher rpm power but can cause lean
> pinging at full throttle.
>
> Since you already did most of the ignition, I'd suggest start by cleaning
> the connectors (watch you don't get contact cleaner on the paint and use
> a good dilectric grease to keep the water out.
>
> And clean the idle air passage.
> http://revbeergoggles.com/tb/tb.html
>
>
> The other thing to do is reset the Jeeps brain. Just pull the battery
> for 10-15 min. Amazing what that can clear up sometimes.
>
>
> --
> -- 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!
>
>
>
>

Dirty TCC connector or TCC starting to go. I fix 42re's on Heeps all the
time.