'95 Cherokee electro-gizmo problem

[RobMD]

You might remember that I completely rebuilt the 4.0L in my Cherokee with the 5 speed.

Everything works great except at times the engine seems to jump in between a lack of power and lots of power, lurching. If you shift gears and drop the rpms to about 1000, you can feel the engine sort of get power and not have any power. (it will jump back and forth between acceleration and no acceleration)

Engine does not miss, it just hesitates to GO...I'm thinking throttle position sensor... maybe the distributor advance/retard control module??

 

[rockyhawaii]

My son's 96 is doing the same thing. No codes come up, and "mechanics" have been replacing parts one by one. It still acts up but not as often, and I predict it will be something simple that's been overlooked. A a dirty intake, or a vacuum leak. You may just want to bite the bullet, take it to the dealer and pay their outrageous diagnostic fee before you lose your mind over it.

 

[RobMD]

In this rebuilt engine, there are no dirty intakes or vaccuum leaks, or anything junky.

I'm positive it's an electrical issue.

 

[Anonymous-0]

fuel pump

 

[RobMD]

really? That would cause it to hesistate and not miss? How might I check the pump?

 

[Anonymous-0]

Had a 94 explorer with a bad mass airflow sensor that did that very thing. Don't know if the cherokee has one or not.

 

[david from mo]

I think on a 95 you can disconnect the o2 sensor ,if it runs better try a new one. Antifreeze will ruin one. Tps is like a acc pump . map sensor is like a power valve. Check your vacuum line to map sensor .I'm thinking you don't have a scan tool thats reads values?david

 

[Anonymous-0]

Possible oxygen sensor. chrylser products are bad about the sensor freezing on an output reading. If it is a frequent occurance it should be easy to see on a DC voltage graph.

When the reading stops reading actual high and low the computer gets all happy with the fuel it is delivering and if you need more, it ignores the throttle position.

 

[RobMD]

ok, ill unplug the o2 sensor and see if that makes a difference. If it makes no difference, then ill just replace the TPS.

I strongly think its the tps because no matter what the heck i do with the gas pedal, it still jumps in and out intermittently, as if the tps was losing and gaining the DC signal repeatedly.

 

[NE-AZ-Hoss]

My 2 cents worth is this: My daughter's 93 Cherokee sport and a friends 89 Cherokee both had power surging and or hesitation issues. Both ended up having the fuel pick up screen and fuel pick up plastic tube off of the inside the tank fuel pump, loose and rolling around in the tank. Either the screen and/or the tube would roll around in the tank at various times causing the problem. Ran the tank below 1/4, put it on blocks, pulled the pump (no need to pull the tank) had to use a net to find the screen & tube. Was a $6.48 fix for both at Checker auto. They both run like crazy now. Maybe it is the same for you? Also we use MAP sensor cleaner for the O2 sensor in the intake tube once in a while like when we change air filters. Helps with power. Good Luck!
Dave

 

[Chris Vangel]

Actually, it is usually the crankshaft position sensor, it is often the last part anyone thinks of due to it"s location. It should be on the driver side of the the bell housing. It reads a series of windows on the flexplate to tell the computer crankshaft position to allow the fuel to fire and timing advance. It's where I would look first given no other issues or clues.

I believe there is a port to check fuel pressure, rather than dropping the tank and such, I would do that first if the fuel system is the way your going to go. I spent 2 1/2 years at a Jeep dealer and replaced many of those sensors that failed. Sometimes they still run, sometimes just crank & no start.

Chris V