3 cylinder 4.0

Since I'm at work and I don't have much time I'll just start a thread...

So, I was on my way to work today... The Jeep was running fine. Running smooth as could be. Naturally I was running late so I was in a hurry. I came up behind a SLOW moving vehicle. As soon as I came a passing zone I accelerated from 20mph to 55mph rather quickly (read 90% throttle). As SOON as I rhomped on the pedal the Jeep immediately started running horribly. Seems like it's only running on 3 cylinders... Soooo, after the embarassment of watching the 20mph car go creeping by my broke down pile of junk I poped the hood with it still running but VERY badly and see nothing obviously wrong... Granted it was dark and I had no tools and I was in a hurry so I haven't tested anything or looked at anything really. I was just wondering if someone had experienced this before and could point me right at the problem. I'm sure it's something simple.

Now, I get to catch a ride back the Jeep in the morning that's still sitting on the side of the road... yay.

Thanks in advance. Andy


Edit: Sorry for the horrible grammar and run on sentences. Still in a hurry...

with no diagnostic info and nothing other than a description I'm just going to take a shot in the dark and say water in the gas since you are back east and it's winter time :dunno:

My first thought was fuel filter, but water or sediment in the tank both also make sense.

BTW, just incase you can't read my sig...and I forgot to include this info... it's a 93 sport 4.0.

It seems more electrical to me. It was so SUDDEN. As soon as I hit the gas it started spitting and spuddering... Now, it will start and idle (rough) for about 1 minute then cuts off... It's acting like it has an extremely bad vaccuum leak and only 3 cylinders are firing.

I could see it being fuel also... I'll check fuel the fuel system first thing.

After that the obvious...

Distriburer
Coil
wires
tps
all the other sensors

Could it have skipped a tooth on the distrubutor?

lowrange2 said:

Could it have skipped a tooth on the distrubutor?

Click to expand...

Not likely.especially if it will still run (albiet poorly) at idle.

try putting a small amount of fuel into the TB, if that smoothes it out for a second it's most likely a fuel delivery issue.

Other idea, how are your motor mounts? could you have yanked your engine ground?

Hmmm, never thought of that. Mounts seem decent. Ill check that too.

Start with the basics, check the plugs. I had this happen to my 92 not long after I got it and put in Bosch Platinum +2 plugs. Was running fine and went to hit the gas to turn left from a dead stop and suddenly lost all power and a big plume of white smoke billowing from the exhaust. Come to find out one of the plugs decided to release the center ceramic and electrode and the piston played ping pong with it in the cylinder.

Always review basics first, then onto fuel and engine management.

How old are the plugs, wires, cap, rotor, fuel filter? Replace all if it's been a while.

Fuel pressure should be verified with a GAUGE.

After the above, start testing sensors, starting with the "throttle position sensor", as it would be the one most suspect for the symptoms you describe.

Good luck and be sure to update us!

Greets.., You might also check the oil pump ears.., as when one of the two breaks, (it ought to stay captured in place, but will not be solid), the blade of the distributer will not operate smoothly within the slot that the two ears provide, and thusly will run really poorly, with a loss of power too. So, just take off your Dist. Cap, and inspect the rotor/cap for obvious damage, as well as rotate the rotor back and forth to detect slop. Such a situation is rare, but it will cause at the very least, the same symptoms you describe.

Another thing to check are your vacuum lines, starting with your vacuum tank, if you do not have a vacuum gauge tester.

birchlakeXJ said:

Always review basics first, then onto fuel and engine management.

How old are the plugs, wires, cap, rotor, fuel filter? Replace all if it's been a while.

Fuel pressure should be verified with a GAUGE.

After the above, start testing sensors, starting with the "throttle position sensor", as it would be the one most suspect for the symptoms you describe.

Good luck and be sure to update us!

Click to expand...

Bingo. Eliminate the easy stuff first.

Well, that was easy. Took about 5 minutes to find this... No wonder it was running bad. I can't believe it was still starting. It was completely spinning around in there. There was nothing locating it.

Anyone ever seen this happen?

I can't believe it was running either.

Every once in a while, we get a report of a disintegrated rotor. How many miles on this one?

When you replace, buy PREMIUM ignition parts. Many parts stores have two levels of secondary ignition parts. Base and premium. Premium is not much more and is mfg. of better materials. Worth it.

This is a good time to do a complete tuneup.

I've only had this Cherokee for about 2 months. It had a fresh tune up when I got it.

I went by the O'reilly's that I used to work at and compared that one to the premium one. The one that was in there was obviously the cheaper one. I ended up buying the accel rotor button and cap and slapped it in there.

Purs like a kitten now.

I noticed when I was under there that my AC clutch wasn't kicking on. Now I get to search that cause I sure would enjoy some AC in the upcoming months.

Thanks for the help once again, Fellas.