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motor make weird sound when u turn it off

1K views 5 replies 3 participants last post by  gros16 
#1 ·
ok after i have run the for lets say 5min when i turn it of it generally makers this really rought sound as if its still trying to kick over or some thing hard to explain but if u heard it u know what i mean.
The engin is a stock standard XF fairmont of a mates which does idle a bit hi could this do it?
 
#2 ·
Firstly - Im not really sure of the setup on the XF motor but:

If it has a Throttle Positioning Solenoid it may not be operating. The throttle positioning solenoid is a switch which basically sets the idle for the car when the ignition is turned on, and then when the ignition is turned off the solenoid lets the throttle drop below idle hence killing the fuel to the cylinders.

When I first got my XD the idle was set using the fast idle screw (which is not good). If I was running it on petrol (its duel fuel) and I turned it off when it was hot it would splutter and try to keep running for about a second or two. All I had to do was reset the Throttle Positioning Solenoid to control the idle and it was fine. The main reason I think it was disconnected was it lacks the power to actually push the throttle body without tapping the accelerator in the car.

If your car if EFI, or that isnt applicable:

What fuel are u running in it?

If you run low octane fuel (like standard unleaded and selected bad quality LRP) you can get 'run on' in higher compression engines. (this is where the engine wants to keep running after the ignition is turned off which feels like the engine shaking violently)

Ive found if you run those engines on BP ultimate or similar high octane unleaded with some upper cylinder lubricant mixed in with the fuel it has no troubles.

Good luck. Matt.
 
#4 ·
** This isnt an easy procedure, if you think any part of this is too hard, or confusing it is best to find a person with a workshop manual and consult them before trying.**

If you take the air filter assembly completely off to expose the carby you should be able to gain access to it.

Hard to explain what it looks like. It sorta like a central locking motor, its a solenoid with a pushrod which contacts a flat paddle on the throttle linkage. (just touches on it, not connected by a linkage etc) It should have 1 wire running to it from the engine bay (which should be connected, good to check this). Make sure your not looking at the automatic choke, I think that has 2 wires running to it???

If the car is automatic choke, warm the motor up to normal op temp. If its a manual choke dont bother. (this eliminates the autochoke from the system).

Now if you get a friend to turn on the key from accessories to ignition while you look in the engine bay around the carburettor. You should hear a 'click' when the solenoid lifts and see the throttle increase. If you dont hear a click get your friend to push on the accelerator and see if you hear a click then.

If you hear the thing click, but it isnt pushing against the throttle paddle the engine has its idle set by the fast idle screw. If it did push against the paddle and raise the throttle, your problem is elsewhere.

If it doesnt contact the throttle, turn the key onto ign, and make sure the solenoid has lifted. Now loosen the retaining nuts on the solenoid and raise its height until it just contacts the throttle plate. Turn the key to off. Now find the fast idle screw (screw that the throttle previous rested on) and unscrew it until the throttle paddle rests on the solenoids retracted position. (this is only a guide, the fast idle may need to be readjusted so that the choke operates correctly).

When you turn on the key to ign, the throttle should now lift up. If it doesnt, push on the accelerator and you should hear and feel a *click*. (this means the solenoid is wearing out and lacks the power to overcome the spring. If this happens you may need a new one).

See if the engine starts, and adjust the idle by adjusting the position of the Solenoid. I recommend you do this with the air filer on, as it gives a better result.

**If all of this fails and the thing wont run - reset the idle using the fast idle screw and retract the solenoid away from the throttle paddle so it doesnt touch.

If this made no sense at all, you can get a gregory's manual from the local auto supplier. They only cost about $49 and they come in handy for explaining all of these inner workings.

Hope you have some luck with it. It took me about a week to get the car running right, and that was after I purchased a workshop manual.

(And as for the flashlube, im not sure about your model. I know my XD which has the Alloy Head I not Alloy Head II doesnt have hardened valve seats and needs flashlube. If the XF was designed for unleaded fuel only, then it doesnt need the flashlube. If it was designed for Super fuel (or LRP these days) then it most likely will.)
 
#5 ·
I have heard of this happening in a mates VC commodore. Car had many k's on it. what was happening was that there was so much gunk in the motor that when it had run for a while the crap inside got so hot that when he turned it off it still ignited a bit of fuel and the moter would turn over a few times really roughly.
 
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