97 jeep cherokee sport acceleration problem

i got check engine codes po135 & po138. when i accelerate quickly from a
stop it hesitates badly
and shakes and then moves all of a sudden.i changed the 02 sensors but
still have the same problem. it doesn't hesitate when i'm moving at a good
speed. mechanic is stumped. any help would be greatly appreciated.

edfisher wrote:
> i got check engine codes po135 & po138. when i accelerate quickly
> from a stop it hesitates badly
> and shakes and then moves all of a sudden.i changed the 02 sensors but
> still have the same problem. it doesn't hesitate when i'm moving at a
> good speed. mechanic is stumped. any help would be greatly
> appreciated.

http://revbeergoggles.com/Fixes/diagnostics.html

WOT does not use the O2 sensor, TPS and coolant temp are the
primary two sensors for acceleration mode.

So, how's the throttle position sensor doing? It should have three lines.
The outer two are 5v and ground. the inner one should smootly move

The coolant temp sensor is usually not the problem, and you can check
that with the temp gauge.

It can also be a failing coil (which sets no codes) or any general problem
with the spark side. (coil, distributor, rotor, cap, wires, plugs)

I'm leaning toward spark. How long has it been since you put new cap/rotor/wires/plugs?

For testing the TPS
----
If your moderatly skilled with electronics and have a digital volt meter
you can test the TPS sensor. There are three leads. one is ground, one
is voltage, and the other varies as you move the throttle body.

Basically:
Turn the ignition on but do not start the jeep.
back-probe the connector and find the ground and +5v
(should be the outside two wires)
If there isn't 5v there then you might have a break in the harness
or just not a good contact with the wire.
Now measure the center wire against the ground.

Throttle butterfly Voltage
CLOSED >200 mV
OPEN <4.8 V

The transition between full open and closed should be smooth
with no jumps or dropouts.

----

--
DougW

thanks doug. i haven't had any kind of tuneup since i got the car 2 years
ago. the cooalnt temp
sensor was changed a few months ago along w/ radiator and water pump. i'll
check the tps.

i forgot to add that the problem only happens when i'm making a turn or
after i just turned.
i'm also getting a rotten egg smell.

The smell is from sulfur in your gasoline, try changing brands...


"edfisher" > wrote in message
lkaboutautos.com...
>i forgot to add that the problem only happens when i'm making a turn or
> after i just turned.
> i'm also getting a rotten egg smell.
>

could somebody help me with the acceleration problem? i've had just about
everything checked by mechanics including the main computer.

What were the results when you checked the TPS? My Cherokee had problems
like that until I cleaned it up. Also today I cleaned my Throttle Body and
it's running quite well now.

Troy


"edfisher" > wrote in message
lkaboutautos.com...
> could somebody help me with the acceleration problem? i've had just about
> everything checked by mechanics including the main computer.
>

Well, you keep coming up with more symptoms, so I decided to wait and
see what 'else' is also going on......

You have so far refused to accept that the TPS connection might be at
fault which is the first place to look, but the stinky exhaust just
screams 'plugged up cat'. You check that with a vacuum test I believe.

A dead distributor cap (if yours has one) can cause bad burn (stinky
exhaust) and bad acceleration, so can dead spark plugs and you have 'no'
idea when the vehicle last had a tune up.... I would check those and
clean the TPS connection before spending money, but....

Anything else?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

edfisher wrote:
>
> could somebody help me with the acceleration problem? i've had just about
> everything checked by mechanics including the main computer.