2003 TJ - Chatter/stuttering/jerking on take off under load/low RPM's

benmack1 · May 11, 2015

2003 TJ with 4cyl 2.4L and NV1500 5 speed, just under 70K. Note this is the year they changed away from the ax5/2.5 so not the more common driveline/engine combo for whatever its worth. Jeep has always been a garage and highway queen, never abused or driven hard. Most of the 70K are commuting miles (30 mile hwy runs). Never off-road, stock and orginal everything (just a sissy jeep).

When I take off from a stop or slow roll in 2nd gear I get a stuttering. It can happen at other times (see below) but that is the most pronounced. Doesn't really do it when taking off in 1st only when the motor doesn't have enough RPM's for the torque it seems to need. The motor is bogging down and it feels like the clutch is slipping but I assume if the clutch disk were bad the rpm's would run up when it slipped? Sorry, never had a clutch fail so not sure what it should feel like. This seems the opposite of what I'd expect, the engine is bogging down and jerking, chattering, stuttering (not sure the right term) then translates to the driveline on to my seat and ass.

This thing is gutless on the best days and this also happens in higher gears too when I am maybe a gear too high for my speed. Jerks and boggs down. For example uphill on the fwy, get slowed by traffic so let up on the gas pedal, then when I get back on it, it will stutter and jump once or twice before it catches up. Again, feels like it is slipping but I notice the motor RPMs are matching the jerking/slipping. If I downshift and get into a better RPM/torque range, it revs and goes just fine with no jerking.

If I wind it out as I go up through the gears it seems to be fine this 'problem' is only when the jeep is under alot of load and behind in RPMs. It seems to be getting worse slowly as well over time.

Any thoughts on what's the problem or how to diagnose further?

ord.sgt.26NC · May 16, 2015

sounds more like a miss thats more pronounced when you need the power but you are in too high a gear for the situation.In a lower gear,your rpm's are up and won't feel the miss so much.Yoda said Become one with the wrangler on your next trip out.Set cruise control and feel with your ass if you get a feeling of going backwards then forewards.This would be a miss. Done any tune ups since you bought it? The coil rail could be a culprit. Under stress,it might not be lighting off as it should.Been there,done that. Put a guage on the fuel rail and see if it's pumping gas as it should. If you were only closer...

Croatan_Kid · May 16, 2015

I'd start with a tune up. Replace whatever you can in the ignition system. I don't know if it has plug wires or a distributor, but at least change the spark plugs. If it has a fuel filter, change that too. Definitely can't hurt anything and all that stuff should be pretty inexpensive.

Any check engine lights?

Tradarcher · May 16, 2015

I had similar problems with a 2.5l wrangler. I replaced both o2 sensors and it cleared up. No CEL ever.

shawn · May 16, 2015

If it weren't a 4 CyL, I'd offer to take it off your hands.

benmack1 · May 16, 2015

Starting with a coil, plugs and wires. Will report back once I get a couple hrs to change those. Have to take off airbox and throttle cable and throttle body on the 2.4 to get to cylinders 2 and 3. Great Chrysler engineering (I have read this is the neon motor). It's at 70k and only had oil/lube/air filt maint. Will move to sensors and fuel delivery after that I guess. No cel ever with this one. Thanks for the cmts

benmack1 · May 20, 2015

Plugs!!!!! Replaced the plugs, plug wires and ignition coil and it runs like new best I can tell. I searched around and actually found a TSB for the 2003 wrangler with 2.4L. The plugs and plug wires seem to have been failing especially in cold climates. This was a TSB back from 2004, so I guess mine being in NC all that time the plugs and wires must have done better for longer. It said something about a thermoset plastic in the wires but also they changed the plugs to a different champion number so I am not quite sure what the problem was but it seems it was never right from the start but I made it 70K and 12 years. Noteworthy is when Jeep came in they did the R and R without asking but NEVER did a formal recall. So if you came in for whatever during warranty period they just replaced but after the warranty, scew it I guess. The plugs were original based on the champion numbers. This 2003/04 wrangler SE 2.4 L 4cyl is an odd duck of the TJ era. It is the neon, PT cruiser engine. It has been great other than this little episode and this wasn't that big of a deal. The fix was <$100 and I probably replaced more than necessary but you have to remove the air box and throttle body to get to plugs 2 and 3 so I figured screw it I didn't want to mess around again if I didn't get the entire problem.

Old plugs. #1 and #4 the connection ends were very dirty. Champion number REMCC5 is the original number. The TSB called for a REMC replacement. Not sure what all that means.