Engine over-run - Perth-WRX.com

Sayers · #1 07-09-2010, 04:05 PM

I just finished replacing all the vacuum hoses on the wife's MY99 WRX and ran the engine to make sure the idle was okay, then manually pushed the throttle to test it with a few revs. Whenever I released the throttle, instead of the engine cutting back immediately it would slowly (1-2 seconds) return to normal idle.

When I turn the car off the engine goes for a couple of extra revolutions before stopping - not sure whether this is related but it's done this for the past 6 months or so, ever since we bought it.

Just wondering whether it could be related to the IACV? Maybe needs a clean? I've not put upper engine cleaner through this one yet, but it's due.

Dawn Patrol · #2 07-09-2010, 05:42 PM

If I rev my car in neutral it usually takes about a second to drop back to idle.
Hopefully it's normal...and replacing all the hoses made your car back to normal. Otherwise I may also have a problem...

Sayers · #3 07-09-2010, 07:07 PM

I have two identical MY99s here - mine and the wife's. I usually spot problems in hers straight away because I've had mine more than 11 years so I know every squeak, rattle and roll.

It's probably nothing, but the engine definitely gives a couple of extra turns after you switch it off. It's like it's reluctant to stop.

tuna · #4 09-09-2010, 07:56 PM

no aftermarket modifications to it? fpr?

Sayers · #5 09-09-2010, 08:24 PM

No mods. I just fitted a new radiator to my own rex and while I was revving the engine to burp the coolant I realised it does the same thing as the wife's car. I can't have noticed it before on my car, which is ironic given what I was saying about knowing the thing like the back of my hand.

However, when I switch mine off at the ignition it cuts out right away. Her's sounds like it's turning over a couple more times. That's the main thing I'm trying to debug.

(I did the UEC the other night so the rain would disguise the clouds of evil-smelling white smoke drifting across the neighbour's place.)

tuna · #6 09-09-2010, 08:30 PM

definitely a stock ecu? no interceptor hiding under the carpet?

sounds like a timing issue anyway, try swapping ECU's to see if it goes away.

Sayers · #7 09-09-2010, 08:33 PM

Thanks for the reply.

I'll take a look but as far as I know it's a stock-standard hatch. If there is something aftermarket in there it's not doing much because my identical MY99 with a stock ECU seems to have more go.

dtrally · #8 09-09-2010, 10:03 PM

I don't think you can swap ECU's without recoding the immobilizer/transponder thingy Stace?

Perhaps you're noticing the extra run-on because your're looking for it while standing in the engine bay, thus the gearbox mainshaft and extra mass is adding to the flywheel effect? Try it with the clutch in and see if it's different.

fffffred · #9 09-09-2010, 10:10 PM

is the car at operating temp or cold? Could be the engine keeping the revs higher at startup to warm up??? If you can't fix it with a hammer, it's an electrical issue...
________
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Sayers · #10 09-09-2010, 10:43 PM

Normal temp. My wife gets home, puts the car in the garage, I go out to say hi and I notice the extra turn or two of the engine when she switches it off.

It's no big deal, I just want to catch it early if it's going to turn into a bigger problem.

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