I just swapped the injectors, I can feel it clicking. Wiggling does nothing. Harness is good. Still have all the looming over it, supported well too. Is it possible to have a bad spark plug even if the end of it looks good? Cap and rotor cause misfire? I unplug number 6 and the arc is insane! I unplugged it once with my hand and the arc jumped through me... damn that hurt too! So at least I know the coil is good, lol! I did another time and used my hose puller pliers, arc was jumping over 1" away from spark plug wire. Ive taken the plug out before and the end looked ok, checked the gap to .035" and put it back in.
Im assuming that because of the power of the arc my coil, cap, and rotor are ok. Is it possible for a spark plug to ground out before it reaches the electrode?
I watched the bleed down in each cylinder, it would take like a minute or so for ten psi to bleed off. Pretty much all the cylinders were consistent. I dont know what the stock specs are for cylinder pressure, I do know you need at least 120psi for a healthy engine to run. Regardless all these numbers are impressive for any engine with 280,000 miles!
The idle has gotten smoother, however she still kinda runs a bit rough. Since its a smoother idle I can hear an exhaust leak near the back of the block, probably cylinder 6 exhaust pipe. I wonder if my header is cracked? Would that cause a poor idle too? I cannot locate the exact location of the leak, its not the coupler, and it defiantly near the head!
Congratulations. I'm happy you stuck with it and found it.
The cracked manifold probably would not cause the rough idle.
I'm not happy with your choice of spark plugs but that's just me. I prefer NGK.
With the engine cold, tighten all your intake and exhaust manifold bolts and nuts working from the center out toward the ends.
Also do this for your idle and it's normal maintenance anyway.
Courtesy of TJWalker:
The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.
CLEANING THE JEEP 4.0 IDLE AIR CONTROL
Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)
“Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged
Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.
Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner
It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled
So after a full tune up Im still having issues. New plugs, wires, cap, rotor, oil change.
Start engine, immediately dies. Restart, runs like one cylinder is not firing, rev motor or start driving, motor begins to run normally. During this start overwhelmly smell fuel out of the exhaust.
Could my coil be starting to die? I dont think it would be since It doesnt run like all cylinders have the issue. Feels like one is off. While running has a slight missfire too... can hear it in the exhaust tone. "burrr, pah, burrr, burrr, burrr, pah, burrr, burrr, burrr, burrr, pah." Sorry that was my attempt at wording exhaust sounds, lol!
Any help guys would be awesome! She my only daily driver right now, and I cant afford to have her break down. Thanks!
So shes running really rough now. Ive taken the coil and my ignition module to Autozone and had them tested, both are good. New cap, rotor, wires, plugs. cylinder PSI is around 120 per cylinder. new throttle position sensor, IAC, air filter, and oil change.
Start it once and shes putts and dyes. Start again and you have the hold down the throttle and it feel like Ive got a dead cylinder. After you start driving away it clears and runs normal, however REAKS of fuel and bad exhaust. Any thoughts? I need help here please? Thank you!