1988 Jeep Cherokee Hesitation

HARVHESS

MEMBER
1988 JEEP CHEROKEE

Engine Performance problem
1988 Jeep Cherokee 6 cyl Two Wheel Drive Automatic 250k miles

This is a California Jeep so no ignition switch code check available. On a cold day the engine must warm up before the car will stop hesitating on acceleration. On a warm day (>60F) it is almost OK without warming then engine. So ambient temperature is more important than engine temperature.

Also, when engine hesitates the electronic tachometer goes to zero.

Please help.

Harv Hess

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Below will cause the engine to hesistate or stumble

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Sunday, May 3rd, 2009 AT 7:23 PM

HARVHESS

MEMBER
2 POSTS

Re 2147394423, I am Harv Hess, Password Daisy.

I believe it is significant that my electronic tach goes to zero when the car hesitates. The tach operates from the high side of the ignition coil which indicates the coil voltage drops to zero also.

To me this says the problem is electrical and not fuel related. Please consider this and reply. Ambient air and engine temperature are also involved.

Harv Hess

Was this

answer

helpful?

Yes

No

Monday, May 4th, 2009 AT 11:06 AM

RASMATAZ

MECHANIC
75,992 POSTS

Sir-The possibilities I have given you is mostly electrical/electronics components and needs checking to rule out the hesitation problem. Could be very well be a problem with the crankshaft position sensor. If you feel that am not assisting you right I ask you to message the management for further assistance

Was this

answer

helpful?

Yes

No

Monday, May 4th, 2009 AT 11:26 AM