90 wrangler with a 258 6 cylinder engine, has a miss all the time. idle to 4000 rpm, some days it is worse than others. rebuilt carb, new plugs , wires dist cap and roter button, new ignition module new coil. checked all connection between components. Cannot find a reason why it is missing. It is intermitant, it is not a consistant miss like a one cylinder is missing. random.. Please help!!! Geoff H.

Check for vacume leak including intake. Spray some carb cleaner around intake and vacume hoses and listen for engine rpm to change.

wrangler? YJ? 4WD"?
what engine, what fueling system. Carb. or EFI?
2.5 L AMC 150 I4 Complete engine specs[show] 4.0 L AMC 242 I6 Complete engine specs[4][show] 4.2 L AMC 258 I6 Complete engine specs some 87s have a carb. does yours, (nobody can fix enigine not kwowing both facts above and what transmission,.


stalls , moving, only. at stop lights or between gears.
but never just parked idling.
if its random , that would be the EGR valve sticking open.
if EFI , bad idle switch.
if Carb bad dash pot. on carb.

The engine coolant temperature is high. Your other Codes are for missing cylinders on cylinder 1,2,3,and 4. Get the Codes cleared and start over. Changing the plugs and wires,etc could have generated the missing cylinder Codes.

Autozone,Advance, and Oreilys will scan for free.

Check your engine for an IDLE SPEED CONTROL SOLENOID, which may be in the intake. Or a fuel pressure regulator.

A lot of times people work on the spark side and forget the fuel injectors. They can cause a miss.

Most carb. engines should idle between 725 and 750 R.P.M., lower the idle and be sure to check the timing. You should have an emissions label under the hood to explain the idle and timing.

The problem is in your carburator. Was it rebuilt in a shop or by yourself or a friend?Did they know what it was going on? It could be that the float level is too low. It could be that you have the plunger rod for the power valve in the wrong hole. It could be that you just need to adjust the mixture screws on the front. I would start with the mixture screws. Turn them in until they seat but don't force them,be gentle. Turn them out 1 and 1/4 turns each and start from there. You will have to turn each one separately from here.Set your curb idle about 500 RPM and turn 1 screw out until you hear the idle start to go up and then back it off until it starts to falter or miss, them come ahead just enough to bring the engine out of that. Then do the same with the other screw. Reset your idle and rev the engine by hand, a couple of cracks and then crack the 4 barrels open and let go. If it stalls then open the idle screws about 1/8 turn and try again. When the engine will return to idle off the 4 barrels without stalling your mixture screws are set right. Make sure you keep resetting the curb idle, usually 500RPM for a standard and 750 RPM for an automatic.
If you rebuilt the carb yourself then look on the rebuild sheet that came with the kit for your engine application and make sure you have the power rod in the right hole and that you have the correct float level. Different applications have different float levels even with the same size engine. Set them for the engine you have it on, if the carb came off something else. Hope this helps.

To set carb adjustment, first set timing correctly, then put both a vacuum gauge and tach on the engine. adjust one idle screw to highest vacuum reading and highest tach reading, then do the other one. go back to the first and re-adjust again, then the other. I find that if you have a mechanical screw or a solenoid that holds idle speed on the linkage, turn them back so that engine is idling at the lowest possible rpm without stalling before making adjustments, then when finished, bring idle rpm up to recommended rpm using those. On an older carb, usually the idle screw covers have already been removed. If not, you need to remove them before you begin, usually best done with carb on a bench.

bad fuel pump can cause this or plugged fuel filter but i believe they are one unit

hello, i first must ask why that engine would EVER be reved to 4000 RPM? it is likely you are up against the rev-limiter and your ignition is made not to over rev. be very careful....4000 RPM on that engine could/will severly damage your tourque convertor........very expensive it is common for the EGR passages on that model to plug up with carbon, remove valve, clean ports, and retest for low speed miss/hesitation, good luck....marty

The rev limiter won't allow it to rev above 4000 in park. Will it go above 4000 on the road. Does it miss at ldle or under a load.

I believe that you may just have a bad float in the carburator i had the same problem in a similar truck after i rebuilt the carb and also changed the float it solved the problem.