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Low idle + spiking oil pressure.

A

Alexw

Member
Hi there,

I usually post in the 944 forum, but I moved my dads '83 924lux the other day (I put my 944 next to his 924 in the garage [:D]) and i noticed the idle seems to be a bit low, hovering around 750 - 775 rpm and feels rickety when it dips low, you can feel the vibration through the whole car. Could this be engine mounts? Does it have an ISV like the 944?
Also the oil pressure guage kept spiking for no apparent reason, it was at about 7 (i'm assuming not bar?? That kpa(?) reading, im not sure [:)]) when sat idling but would suddenly spike to 10 (maximum of readout) for a second then go back to normal. Guessing again, would this be more likely to be the sender and not a problem with the engine?
 
ISV problems in VWs at least usually manifest themselves as vast fluctuations in revs, 1000rpm or more is not uncommon. You'll need to confirm this with someone else but i don't think the K-Jetronic system has an idle stabilisation valve of the sort that is known to cause problems, it's usually Mk2 Golfs with LE-Jetronic or whatever that suffer. Checking your throttle body, metering head and all the breather pipes for that brown sticky gunk would be a good place to start making some eliminations, carb cleaner will remove it. Breathers are often overlooked and in some cases left broken or removed completely but i promise you they're integral to a smooth running engine. However it may just be that it needs setting back up on the exhaust gas analyser and the ignition timing and idle speed resetting. If it only happens when it's cold check the Control Pressure Regulator, Thermo Time Switch and Warm Up Injector, mr Haynes has all the procedure for this.

As for your spiking oil pressure i have a suspicion that low quality of power/signal to the measurement system may be messing with unsupressed sensitive electronic instruments such as the gauge, or that engine judder is causing bare wires to short or connect badly. It's only a guess i'd have to see the gauge moving to be sure but either way i suspect if you sort your idle out you'll see an improvement or cure to the gauge flutter.

One of the moderators '924nutter' will be able to advise you better than me.
 
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