What could be causing a '98 XJ8 to stall at idle?

Question

Every once in a while, without warning, the vehicle will stall. This only occurs at idle, such as at a stop sign, etc. Any guesses?

1998 Jaguar XJ8

I do not own this vehicle, but am considering buying it. The vehicle could potentially be very inexpensive to buy, however I'm trying to get a ballpark figure of what it will cost to repair. The seller has described the problem, so I only know what they have provided.

Answer 1

s you indicated in it's profile, this vehicle has fuel injection.
Fuel injected engines have a device called a "idle air bypass
valve". This valve is responsible for maintaining the engine's
idle speed. Hence, if it's not working, the engine will stall.
Now then, as you indicated, stepping on the gas pedal WILL
keep the engine running when it's about to stall. This clearly
indicates a faulty idle air bypass valve. You see, by stepping
on the gas pedal just as the engine is about to stall, you are
essentially compensating for a faulty idle air bypass valve in
that you're increasing the throttle and thus giving the engine
enough fuel to stay running.



You'll need to have a mechanic verify that the idle air bypass
valve is faulty. If this is indeed the case, have it replaced.
NOTE: In a situation like this, some mechanics may offer to
replace several other items related to the above. For now,
just stick with the replacement of the idle air bypass valve.
This should correct the problem. You can always return at
another date for the other items the mechanic suggested.

Answer 2

There really are too many possible causes to list.

In terms of guesses:

Most likely cause is a fuel filter that is clogging up.
I'd also recommend getting the injectors cleaned.

Other common causes.
Bad spark plugs, when was the last time you did a tune up?
Clogged air filter, so you're not getting enough air into the engine at idle.

Answer 3

COuld be the throttle body needs cleaning, thus in that area, is the Idle air control valve that could also be gunked up causing it to do what you mentioned.