Intermittant Prob- 00 XJ won't idle, vac leak?

00 XJ Sport 4.0 Auto 4x4
K&N FIPK
Flowmaster muffler
(K&N and Flowmaster were installed 1+ year ago, problem started recently)

Sometimes, when I start my XJ, it'll crank over, catch, then instantly stall if I don't have my foot on the gas. When it refuses to idle, if I open the throttle, I get a whistling sound from the driver's side of the engine bay.

I can get it to idle (although it's a low idle) if I downshift to '3' and compression brake for 20ft or so to build vacuum.

Problem tends to occur more on cooler mornings (50*F... this is CA afterall) and goes away on it's own after compression braking/engine warms up.

Because of the whistle, I'm almost certain it's a vacuum leak, but was hoping someone would recognise the symtoms and know exactly where the leak likely is. :roll:




Oh, one more thing. A part of my engine wiring harness touched the exh manifold and melted away the insulation on a couple wires.

It's the section of harness coming out of the front of the fuel rail, going down in front of the engine, and connects to the O2 sensor in the exh downpipe.

The melted part is right next to the thermostat housing, about 1" of insulation on all the wires (4?) is gone, and they're in contact with each other; I'd like to find a plug-in replacement harness section, if available. Anyone have the part number?
Also- what's the effect of these wires shorting on each other? How is it affecting driveability? :dunno:

???

??

Fix the wires, thats almost certainly the problem. The computer can't make good decisions if the signals from the sensors are all screwed up.

The whistle is just your intake.

j99xj said:

The whistle is just your intake.

Click to expand...

Even though it never made noise before? Both symptoms showed up about the same time, but I've had the intake installed for over a year with no whistling.

Maybe you never started it with your foot on the accelerator pedal until recently? On a cold start, increasing the RPM's on startup, the suction sound will be considerably louder than normal.

Update: the whisting seems to only occur at part throttle (around 20-50%). If I let off the gas or get on it more, the whisting goes away.

If the wires going to the O2 sensor were shorted together, would that have the effect of opening my EGR all the time?

Would an open EGR cause whistling?

No EGR on a 2000.