shoggoth80

Ok... so....my Jeep runs a 2.5L engine. I ordered a Crankshaft Position Sensor for t he 2.5... it does not fit my transmission's housing for it.
On a whim... I checked what the 4.0L engine's CPS looked like online... and it looks like what I have on my Jeep. So... do I have a better tranny than the AX5? Just odd... and the ONLY way I can see this the way it is, is that someone put the other trans in there before I bought the car... but I thought the 6cyl and 4cyl used different transmissions/bell housings?

For what it is worth, my car is still doing the herky jerky on the highway from time to time... but if the CPS is bad, wouldn't the car not start at all?

shoggoth80

Ok...so anyone who may be curious: I have an answer.
It appears that the 1994 model year is when the sensor changed to the type I am looking at...so I either have a late '93, with '94 features... or I have a later transmission in there. Either way, I got the part returned, and getting it swapped out for the proper one.

If anyone has a 1993 Jeep... take a good look at your CPS before you purchase a replacement... I made the mistake of believing parts parity was maintained through the model evolution.

BuckB91XJ

Normally a CPS just craps. They work then, they quit working. There isn't any herky jerky in between. Could be worn ignition pieces or fuel filter plugged or fuel pump going bad.

shoggoth80

Ignition pieces are pretty much all new. I know, I did them myself. Fuel filter is new... maybe 200 miles on it. Replaced it a few weeks ago.
Fuel pressure reads at 30psi, which is 1psi less than the manual low end spec. This may be something I need to look into more.

BuckB91XJ

You are right on your fuel pressure. It is good at 30psi. You can read your CPS out with a Multimeter. Just google it. You will find the procedure and what a good reading is. If it herky jerkys all the time, you could possibly have a vacuum leak, too.

shoggoth80

The herky-jerky typically happens at 55-65mph on the freeway. Sometimes it'll happen at slower speeds under load (hills), but rare. Also usually happens only when warm. Vacuum leaks are a suspect. Hard to hear, and harder to spot. I am also wondering if a head gasket blown between the cylinders might cause the same symptom. It's a beast to track this one down. I am thinking I might yank the head and do the gasket soon anyway. Cheap insurance. I did overheat a couple times when my water pump was leaking. But this symptom has show up well after I had replaced that. So, I dunno. I am usually pretty good with mechanics, troubleshooting, diagnosing, and then replacing whatever needs replacement. This one has me scratching me head a little still.

I will still swap the crank sensor when the new one comes in. It's not hard, and is good insurance. I'll save the old one as a spare (as I did with many of the parts I changed.