XJR Tapping Noise

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XJR Tapping Noise

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XJR Tapping Noise - 2/4/2008 9:17:14 AM

kmschaer

Posts: 3
Joined: 2/4/2008
Status: offline

I have an 04 XJR. I am getting a faint tapping noise from the drivers side firewall area heard inside the car. The tapping is rythmic and does not change with engine RPM.

Any Thoughts?

Post #: 1

RE: XJR Tapping Noise - 2/4/2008 4:32:20 PM

FactoryJaguarTech

Posts: 2972
Joined: 1/6/2008
Status: offline

Sounds like your purge valve. Was a common issue on 04 XJ. If you replace it, the noise should disappear. Bear in mind I am not there to hear it. So best guess only.

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RE: XJR Tapping Noise - 2/6/2008 5:40:31 AM

kmschaer

Posts: 3
Joined: 2/4/2008
Status: offline

Good call on the purge valve. I have isolated it as the suspect component. Does the ECM send a pulsed output to the valve? It was my undersatnding that the valve remains in a fixed state once the car is running and is between 1/4 tank an full. Wondering why a tapping noise if the signal is fixed. The ECM is not setting and DTC codes, so I assume that vaccum is being held in the canister. There was an issue with the vent valve earlier this year which was setting a gross evap leak code. It was still under warranty and the dealer took 4 trys to get it right. Replaced gas tank filler neck, gas cap, and two reset visits..... 5 days in the shop for a vent valve

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RE: XJR Tapping Noise - 2/6/2008 3:35:38 PM

FactoryJaguarTech

Posts: 2972
Joined: 1/6/2008
Status: offline

It is a pulse width modulated signal sent to the purge valve. If it was stuck open all the time, the car would likely run rough and smell of fuel. The ECM only wants to allow metered amounts of fuel vapor into the engine to be burned off.
The PWM is why it ticks like that.
Glad you found it.

_____________________________

If it ain't broke, don't fix it!!!

(in reply to kmschaer)

Post #: 4