i have a 96 jeep grand cherokee with a 4.0 straight 6. the problem im having is the motor idles good and revs great in park or neutral but when in drive i have to feather the gas pedal lightly because if i give it to much pedal or try to kick it down it bogs down and sputters kinda acting like the cat is plugged. i have had the exhaust apart, and the cat is fine, i have replaced the fuel pump, fuel lines and filter, itc sensor is replaced, along with a new coil,plugs and wires, cap and rotor, and o2 sensors. i have cleaned the throttle body and air filter is good. tps sensor seems to be fine also. it is not throwing a code anymore but is still doing this problem. any input would be greatly appreciated!!!

 

seems like nobody has any answers when it get's a little complicated. here are some things to check for regarding your jeeps symptoms. EGR ( engine gas relief valve ) if it's on your 96. common symptoms include a loss of acceleration power, bad fuel mileage, and the check engine light comes on. IAC ( idle air control valve ) will run okay in park or neutral and lose rpms rapidly as soon as you shift into drive or reverse. stalls frequently. MAP ( manifold absolute pressure ) or MAF ( mass airflow - also called vane ) sensors. engine stalls under load , lack of acceleration power , etc. CAMSHAFT POSITION SENSOR / PICK-UP / RELAY. rough running motor, hesitation , stalls when accelerating. this at least narrows down your search. log on to e-how.com for more thorough info on signs or symptoms. type in the search box , symptoms of a bad idle air control valve for example. lot's of info on every sensor or part that you would ever need to know. it will save you alot of time and money. holler back if you need more help.

 

almost forgot to tell you that sometimes your computer will store a hard code that can only be removed by a garage scanner / computer. an obd-2 device will remove the check engine light and most codes. some, even though it dosen't show itself, are still present in your computer and can shut down your motor unexpectedly thinking it's protecting the motor. this results in ROAD RAGE. lol it wouldn't hurt to swing by a shop where you trust someone to check for the codes if all else fails. if all your sensors are good, you have no fuel or electrical problems, and the problem persists; have the ignition system checked out. not the lock cylinder where you turn on your key. the switch , the condenser, the control module, and the exterior switch box. ignition systems cause similar symptoms as some sensors. it is the most over-looked trouble area on jeeps. one occasional short can cause you months of headaches. put this on the back burner for now though.

 

Check the fuel pressure.

 

I was goingg to say fuel pressure regulator...is that a possibility?

 

The regulator in on the top of the pump, so if you're going to go that far you might as well replace the whole pump assembly.

 

Isn't there 1 on the motor to...I swear I replaced it once lol

 

Not on a 96, 95 and newer have a returnless fuel system, so the regulator is on the pump.

 

Cool thanks for the knowledge...like they say learn something new everyday... especially on here lol

 

thank you for all the helpful ideals to check for. Man ive been a mechanic for years and never quite ran into anything like this. the no check engine light is whats throwing me off! ill dig into what you have suggested and let you know the out come. thanks again!!!