99 XJ 4.0 help

justjeepin86

justjeepin86

Well-Known Member
Joined
Jul 9, 2005
Location
Winston-Salem, NC
So I have searched and read a little and have not come across what I was looking for. My nephew has a 99 XJ that I am trying to help him diagnose over the phone.

Lately when he takes off with it, it will rev to around 2000 rpms and stay there. He had to hold the brake to make it keep from going. Then he says, while driving along and he starts to accelerate it loses fuel like he let out of the gas. When he lets back off, it will pick back up. He barely made it home yesterday and now he says it wont start at all and smells like gas when he is turning it over. Any ideas or a place to start?
 
Could be TPS, IAC, and or Map sensor.

It's fairly easy to check tps and map sensor with a voltmeter.

When a cps goes bad, it will shut off ignition, usually when it gets hot. May shut it off briefly for a second and it comes back on, causing a misfire, or shut off until the engine and sensor cools off before it works again.
 
Do these things not throw an engine code when an engine management issue occurs?
 
Check TPS voltage with key on, engine off. It should be about 0.7 volts. You have 3 wires at the TPS, 5v, ground and the signal wire. Probe the signal wire.
If it is not around 0.7-0.8v, the TPS is bad. Then sweep the throttle while watching the voltage climb, look for a dead spot.
 
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