Dcskateohio

1996 jgc 4.0 bought it a month ago it misfires under a load and sometimes stalls. Sometimes it will drive perfectly fine and other times its about undriveable. No check engine line. Cat has been cutout prior to me owning it so we can eliminate that. Ecu tps rottor button cap and plugs and wires have all been changed. Has a brand new battery as well. When new parts are installed sometimes it runs perfectly fine and only last a day or two. Or new parts can be installed and it automatically runs like crap. Any help?? This problem has me so baffled i cannot afford to throw any money at it and need to get it running its in mint shape its pushing me to the edge to were i wanna just watch it be crushed. Any help or advice would be great! Also saw tons and tons of people having the same issue online but never once saw the solution to the fix.

dave1123

Welcome to CF!

My first instinct is to suggest NGK ZFR5N spark plugs and a new ignition coil. You may also have a worn out distributor shaft bearing. There should be no sideways motion of the rotor shaft. The distributor is a "screwdriver" drive and can be pulled out very easily without messing up the timing. Just mark the flange before you pull it out.

I assume you are aware it's a violation of Federal law to not have a converter, right? Required after 67 for cars and 77 for trucks.

Dcskateohio

Yes i am aware i would have one added but at this point the thing is not even drivable so i am not worried about that untill it becomes drivable but thank you for the suggestions ill check first thing in the am if the shaft wiggles side to side it would be completly bad? Almost thinking at this point its a wiring issue or fuel issue because it starts and idles well just bucks and stalls under a load or sometimes even shuts the whole engine down when stopping or approching a stop

dave1123

Just for jollies, check your fuel pressure. You can rent a gauge at Autozone or other parts stores. It has a hose that screws onto the schrader valve on the fuel rail. It should be 37 to 41 psi at idle for your year.

Dcskateohio

Fuel pressure 46 lbs at idle but when engine reved it does not increase the slightest

Dcskateohio

Also all injectors read out 13.5 ohms when the resistance was checked

97grand4.0

crush it. more fun.
Scan tool is a must here absent good old logical guessing. -+

dave1123

As long as the fuel pressure doesn't decrease above idle, you should be good on that score. IDK what the resistance value should be, but it's a good sign if all of them are the same. In my opinion, everything points to weak spark, like maybe a worn bearing causing the rotor shaft to wobble or a defective cam sensor (the thing in the distributor under the rotor).

Dcskateohio

Thanks for all the suggestions guys it throws no check engine lights and evetything else checks out on the scanner including the long term fuel trim and short term would i check the distributor by wiggling on the shaft? Or could you advise another way?

Dcskateohio

Also dave1123 that seems very possible. Its funny you mention those parts because when i replaced the rotor button with a new one it would barly make it down the street then i put the old one back on the problem was back to its normal cycles. Then i changed all the plug wires and coil wire it would run 50x worse so i started by puting just the old coil wire back on which was longer and cheaper then the new one and boom it was back to its normal cyles run good one moment and like crap the next but whilist the new coil wire was on it could harldy make it down the street. So it is very possible there is a problem with the cam sensor or the distributor itself. Any suggstions on how to check each one of the parts? Thanks

dave1123

Know anybody with a DRB scan tool? They are pricey, but most service and repair garages have one to stay in business.