1988 Porsche 924S

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Woodcutter

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Behave yourself Paul_arse!

So we have had a slight hiccup, car is idling very high at about 2500rpm which is a sure fire MOT failure, so we have re-booked for 4th August.

Hopefully that's enough time to figure out what's wrong. Seems to be an air intake issue but not sure why....I'm hoping @pablo can solve it while I just wash it! :p
 

Gambit

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Woodcutter said:
Behave yourself Paul_arse!

So we have had a slight hiccup, car is idling very high at about 2500rpm which is a sure fire MOT failure, so we have re-booked for 4th August.

Hopefully that's enough time to figure out what's wrong. Seems to be an air intake issue but not sure why....I'm hoping @pablo can solve it while I just wash it! :p
Click to expand...

ahh welcome to the land of k-jet fuel injection! look for a throttle closed switch, or the aux air valve
 

Paul RS

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K-Jectronic is hateful stuff. It's what's used on RS turbos, gave really random bother on mine that fixed itself lol.
 

pedenjohn

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I was told you can check for a split hose by spraying them with carb cleaner and listening for a rev rise. Though I would have thought a hose split would just have left it lumpy. Possibility of maybe a blocked oil breather? I duno much about them to be fair.
 

Mark_C

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It's not k-jetronic if it's a 944 engine.

Only the 924 had that.

2.5 engine has an ECU, electric fuel injectors, single channel ignition driver with a distributor.

have had 2 at home recently as non starters that we've had to rewire completely
 

Woodcutter

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Mark_C said:
It's not k-jetronic if it's a 944 engine.

Only the 924 had that.

2.5 engine has an ECU, electric fuel injectors, single channel ignition driver with a distributor.

have had 2 at home recently as non starters that we've had to rewire completely
Click to expand...

Any idea on what's causing the high idle?
 

Mark_C

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I'd say you have a faulty throttle switch OR IACV (If present) if you have DEFINITELY not got any air leaks - but air leaks are extremely likely because those big old rubber hoses perish like mad
 
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Mark_C

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I might be able to lend you one of each off the one I currently have in the yard as long as the owner doesnt come back from holidays to take it home, just to test thats what it is.

Will fire you details on how to test the ones you have.
 

Jason

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Rubber hoses seem to perish alot on them, last year we put on new fuel hoses in the engine bay, idle was fine then though
 

Mark_C

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Make sure as well no-one has been tweaking at the throttle bypass screw..Could be chasing tails if that's all it is.
 

Mark_C

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Whip off the ECU and stick a tester between 3 and -ve, you should get infinite ohms closed throttle falling to 0 at full throttle. Even a tiny movement should yield a change. there's some adjustment in them
 

Woodcutter

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Just picked the car up and drove it about 1.5 miles and the idle issue has magically cured itself!
 

Woodcutter

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Jas Lad said:
Surprised it was idling high cause it was ok before!
Click to expand...

Must have been something needing cleared out after sitting about for so long.

Did your Dad ask the previous owner if he had any of the old handbooks or anything?
 
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