2.5L Eng Missing at speed/Intermittent

fatoldcapt

New member
Warm Engine Missing, Intermittent

Okay, I need some suggestions before I go into the shop again (that is if it doesn't heal itself on it's own). I have a 94 YJ w/2.5L 4 banger. 131K miles. I just had a new head installed. New Plugs, Cap, Rotor, Coil, Fuel Filter, oxygen sensor. TPS Adjusted, throttle Body Cleaned. Cool Air Intake kit installed. The jeep runs fine until it gets warmed up. Then it "misses" (Shudders)at acceleration and cruzing speed. (It does not stall, idle is smooth and only backfired once) Mostly but not always this happens at around 2500 to 3000 rpms. It's acting as if the timing is off just a little so that it won't take the fule at those few occasions when this happens. Do any of you wise folks have an idea what to check next? PS: The head, plugs and TPS was done first by a shop then I did the rest over about a month with no effect as each was done. I probably should start over and check the plugs unless you have other suggestions.
Aaron
 

My guess would be Catalytic converter or some type of exhaust obstruction. Since you just had all this work done and that it only happens at speed and not at idle.

Good luck
 
Thanks, I'll see if I can find a Cat By-Pass tube and see if it does it with the converter removed. It was burning some water with the bad head. There was rust in the #1 Cyl. Aaron
 

Could be an injector problem, put a long prybar or dowel on each injector to make sure they all sound the same. I just went through this and it was an injector even though it behaved as a spark problem.
 
This sounds quite similar to my issue. Very intermittent. sometimes I can go days with no problem and other times I get to where I want to drive it off a cliff. It will do it at most speeds but the faster I go the less it happens. Makes driving around town a pain. 25 - 45 mph seems to be the worst. at, say 35 mph, steady speed, the vehicle feels like is is starting to slow down, a seat of the pants sense. The engine sounds ok when it does this. But a moment later it sounds like someone put their hand over the air intake on the throttle bodyand I loose all power. If I do not move the accelerator, it just keeps slowing down. If I let off the accelerator or step on the accelerator it recovers.

1990 YJ w/2.5l & 5sp
 
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