So I’m having a misfire and some stalling at red lights on my 96 XJ on a jasper motor that’s under 30k miles. At this point I figured I’ve changed a good amount of things. O2 sensor, injectors, plugs, wires, cap, rotor, TPS, cleaned AIC. I did have a similar problem last year that turned out to be the fuel pump and fixed that, but now I am right back to getting a misfire, did an OBD1 test and got a misfire and alternator code. Any ideas on what it could be would be greatly appreciated.

 

It could be heat soaking at the fuel injector. Is it always the same cylinder that misfires or is it random? You can "rent" a fuel pressure gauge for free from a parts store to test the fuel pressure at the rail.
Were any of the spark plugs more worn than the others? Did you replace the fuel filter when you replaced the pump?
Even though you have low miles ensure that the rubber for the air intake system doesn't have cracks or holes which throw the air to fuel ratio.

 

When was the last time you preformed a general clean-up of all exposed electrical connections? (ground connections, alternator, starter, battery terminals, etc). That is your easy, free, first step before throwing parts. Because the symptoms you list can be caused by a number of things, but one of the most common is voltage problems brought on by connection issues.

 

So as far as the injectors go I did test them and changed the fuel filter, the fuel rod ran about 40 psi which seems a little low. They do hold psi when it’s shut off though but I’ll have to check this time what cylinder is misfiring. as far as the grounds go, I’ve only cleaned the terminals and grounds, I’ll try cleaning Off the rest. I also don’t know if this is relevant but my cruise control doesn’t work anymore either.

 

There are three cables that connect to the throttle body. Ensure that they are all secure.

 

Fuel pressure , crank sensor, check codes, cam sensor, mopar only on those two, .fouled plug, cap rotor .shall I go on? Fuel is low should be up around 50 running. How is the leak down ? Should hold at least 25 for 4 mins or something but I know you can look that up

 

So ran and OBD2 and it read multiple misfire, and that all cylinders were misfiring going to look into more this weekend and give updates

 

no mention of coil replacement?..they can develop visible cracks..visible only when taken off and examined, usually around the back & underside

 

Sorry about the late update, finally got a chance to work with it. I fixed the fuel pressure so now it’s at 50 psi and holds 30 when I shut off. I still seem to get a little bit of a stall, but it’s mostly while the vehicle is cold and when it’s idling in drive - so I’ve only been low idling at red lights, stop signs etc. once it warms up it seems to be better.

 

Got the codes for a multiple misfire, then misfire on 1,2 and 3. Swapped the coil and went with champion OEM plugs. Seemed better for a second, but back to the stalling.

 

Seems you never said what engine you have and didn't fill out your profile, Nick, that would make our lives a little easier LOL.
Do you have an obd scan tool or are you going to Autozone? Misfire on a 96 cannot mean ignition, as they had distributors. The only thing that can mean is the injector circuit resistance is off. Do you have chopped up wiring to the injectors?
Do you have a code for the cam or crank sensor? Have you changed either of them? Thx

 

Did you really just say that? Please tell me you misspoke. Please tell me you didn't mean that the way it came out!


Of course a 96 (or earlier) can misfire due to ignition problems!!!! Distributor, rotor cap, rotor, wires, plugs, AND coil can all cause misfires due to lack of reliable spark. In ohter words, ignitoin problems. Bad connections to the coil or bad grounds in the coil circuit can also cause misfire due to ignition problems.

In fact, I was just going to ask the OP about his distributor when I saw your post. The bushings can wear out and cause a host of problems.

 

ROFL Well I said it but the way you understood it wasn't the way I meant it. What I meant was that the stored code 'misfire' on the obd2 reader cannot mean ignition because it had a distributor, which there is no ignition misfire monitor for. The misfire monitor therefore is telling him that there is a problem on the fuel injector circuits. Unless I am wrong.

 

Whew!

Okay, I feel better now!

 

No beans on crank sensor helping. Starts up, stalled at the first stop sign I hit.