This might have been asked before so sorry if it has. I just got my Cherokee and it has had the long block replaced and lot of other parts replaced. It spudders while driving, "if not in gear its revse up fine" rpm range is 1800 to 2100 after that it does good also at low rpms its good . I just replaced the tps and no better. plugs wires cap is new to.. I'am at a loss here so if anyone can help that would be great.

 

Idle air control valve? Take it out and clean it, see if that helps.

Could also be something as simple as the fuel filter. Do you still have the old TPS? Is it a 5 speed or automatic??

 

I do still have the old tps. and its a auto. Do you know where the idle air control valve is located?

 

right next to the TPS in the throttle body, should be two HEX type screws holding it in.

 

Ok cool i will try that. Any other Ideas?

 

depending on the tps and icv id say maybe fuel pump or injectors. but my guess is its probably your tps. should be reading at 0% at idle.

 

What type of sputter is it?? While your driving just out of no where it sputters or when you let off the pedal, or when you trying to over take another vehicle(Passing)??

At warm-up are there any signs of this sputter or only while driving after its reached temp?

Couple Q's:
How many miles?
When was the last know tune-up?
Last o2 sensor replacement?
IAC possibly..
Is the Check Engine light on?
Use a scanner to pull any possible stored codes.


I wouldnt think its a fuel delivery prob if hes actually driving it around as a DD. My bet would be o2 sensor has gone bad or is on its way out(burnt wires??)

 

So i cleaned the icv and no better. It seems to rev just fine in park but in gear it never fails to sputter and cut out around the 1800rpm to 2100rpm range. If I try to gas it alot out of the sputter it will backfire a bit when I es off. No check engine light comes on ever not even when i just turn the key on " I would say its burned out". The speedo says 168### miles but the long block was replaced about 20k ago. There was a tune up done right before I got it 2weeks ago most of it I should say cap, wires, plugs, from what I see "and I just did the tps". I'm leaning towards the o2 sensor as my next guess? Any other ideas????

 

I dont think the 88 came with a check engine light. My 87 does not have one.

Could be injectors, egr valve , MAP sensor,O2 sensor. it sounds like a fuel delivery issue, as long as the plugs wires and cap rotor are on correctly.

Mine was a bear to figure out, turned out it was the new to me injectors, or one, it was cracked and dumping way to much gas in.

Good luck.

 

Do you know which long block was installed??
Your orginal 4.0 was a renix, do you know if it was changed to a newer model 4.0?

 

Not sure about the long block I will check into it. Can a Shop still check codes on an 88?

 

Well I just drop my Jeep off at a reliable shop here in town I will post what they find out!

 

no

 

Sounds like the exact problem I have. Let me know what the shop tells you. I have a sputter and like a misfire when in gear and light on the throttle around 1500-2200rpm. It backfires from exhaust too.

 

If you havent checked yet, check your fuel line for kinks or anything, I had this issue on a buddies tahoe. Also check the fuel pump afterwards