lumby

I have noticed recently when switching the engine off, on WRX, as the engine noise dies away there is a brief rattle that last literally a second. Any clues to waht this could be or similar experiences.


Any suggestions appreciated

Lumby

Sandman

Lumby
you may be experiencing "run on", this basically means the engine continues to run on after the ignition has been switched off. common causes are high combustion chamber temps due to incorrect timing,incorrect fuel grade ,weak mixture and too high idle speed,depending on age could also be a build up of carbon deposits inside combustion chambers yhe old term "de coke" refers to the removal of such deposits.Hope this helps
Sandman.

lumby

THANKS BOTH OF YOU FOR YOUR HELP , I THINK IT IS MORE LIKELY TO BE LOOSE HEATSHIELD/ EXHAUST RATTLE , AS I AM NOT REVVING ENGINE WHEN I SWITCH OFF

CHEERS

JohnD

iTrader: (5)

Running-on was a problem back in the 60`s and 70`s I remember owning a few cars which would do this. I would engage 1st gear, switch off the ignition and release the clutch to stall the engine before it could run-on. Manufacturers started to install fuel cut-off solenoids to prevent fuel flow after ignition switch-off. Run-on was often refered to as "Dieseling" One problem with run-on was that the engine could momentarily stop as a piston approached T.D.C. then run backwards as pre-ignition occured! with a lot of timing chain rattle.
Enough of the history lesson! With electronic fuel injection fuel flow ceases immediatly the ignition is switched off. I would be most surprised if the engine was, indeed, running-on, I have never experienced a fuel-injected car running-on. As the Subaru engine "rocks" quite a lot as you switch off it could possibly be the exhaust pipe or heat shielding rattling. Get someone to peer under the bonnet and front of the car as you switch off to isolate the area the noise comes from?
Regards JohnD
PS You`re not revving the engine as you switch off are you?

[Edited by JohnD - 1/5/2002 1:41:16 PM]