Hoping for some help with an intermittent idle problem on my 1996 XJ. When I start the XJ, all is fine and it runs perfect. Shut it down, restart, repeatedly, no problem. Then, I go start it up and it won't start unless I push the gas pedal to the floor. As soon as I release the gas pedal it stalls. Then, the problem goes away but then intermittedly returns. I replaced the camshaft position sensor and then the idle air control valve, no luck. I took it to a local garage and they stated their diagnostic computer was not able to communicate with the XJ's computer. So, I replaced the computer (properly, as the VIN was programmed in) and still no luck. The XJ is in immaculent condition, zero rust, 139,000 miles, and we are the second owner. Up until now, it has been a GREAT vehicle and would love to keep it. I also cleaned up the ground connections, those I could find anyway, but still no luck. Any ideas to keep this beauty from being sold for parts? Thanks!

 

Do you hear the fuel pump prime when you turn the key to 'ON' prior to starting?

I'd start with listening very closely for that and if it does prime I'd put a fuel pressure gauge on it and run the pressure test as outlined in the FSM.

If you're looking to get rid of a no-rust 96 with under 140k miles on it that has a little hiccup starting.. I will gladly take that off your hands for a "parts jeep" price.

 

1. Do you start to crank it -then- put the pedal to the floor(when you realize its not starting)? Or do you put the pedal to the floor then turn the key to crank it?
2. Do you actually push the pedal -all- the way to the floor?

These might sound like strange questions, but they matter.

 

PatHenry,

I'll check the fuel pump prime this weekend. I did repalce the fuel tank and fuel pump a few months ago (road debris punctured the tank so replaced everything) and have not had any issues up until a few weeks ago. The stalling is more than just a hiccup. As soon as you take your foot off the gas it stalls, including at stop signs, stop lights, etc. Frustrating as the problem is intermittent but frequent enough that it cannot be driven safely (it has been my teenage daughters vehicle the past couple of years).

Appreciate the response and I'll keep you posted.

Thanks

 

jordan96xj,

Typically, we do not touch the gas when starting. Just turn the key and she fires right up. When the intermittent problem surfaces, which occurs randomly but frequent enough that it's not safe to drive, thats when we hit the gas (after we turn the key to start) to get it started. She then fires up but as soon as you let your foot off the gas, she dies..... Yes, we push the pedal to the floor to get it started.

No strange questions at this point. Need any help I can get.

Thanks

 

Those symptoms are consistent with a low voltage condition. Next time it is running, consider stopping by an auto parts store that does battery/alternator testing and have them test it.

If you have an multimeter, you might take a quick reading of the battery voltage (with vehicle off), then during startup (especially if you can catch it in the act of having a problem).

The reason I asked about the pedal being pressed to the floor, is because if the pedal is pushed to the floor and held there during startup - the engine should not run (by design). Doing this puts the computer into flood-clear mode and will disable the fuel injectors. So if you were able to depress the pedal to the floor, and then crank and start it that way, I might suspect that the Throttle Position Sensor is not sending the correct values to the computer. Bad values from the TPS can also cause the computer to not command the IAC correctly (which will cause the vehicle to stall when the pedal is released).