Blacktop Idle Speed

[thegreatestben]

Did a bit of a search before posting,
Found the blacktop service manual online and it said to check ISC Valve in the case of a high Idle.

I was experiencing an Idle of 3000rpm, it would drop down to 1500rpm if I unplugged the valve.

I've since cleaned it and this dropped it down to 2500rpm, and by clean it I mean pulled it to bits and used carb cleaner then reassembled.

I found that my accelerator cable was a bit tight and was holding the throttles open a smidge. Loosening it off took my idle down to a steady 1500rpm.

Now this is still a bit high for my liking, and this is where I ran out of bright ideas to fix it. I can get the car to idle at ~1000rpm or lower by pinching this hose with a pair of polygrips.



Does pinching the hose effectively do the job the ISCV valve should be doing? Is my ISCV stuffed? I noticed on the back of it I can change the tension spring (I'm not sure what it is exactly, but you can adjust it in a simaler fashion to adjusting a TPS). Perhaps I have just set that wrong?

Any ideas?

[frost]

yeah pinch that hose with yellow arrow shut and see if it drops to about 1000rpm, it should be 800rpm but thats a adjustment you need to do later, if it don't drop to 1k then you have a air leak somewhere, if it does then its stuffed isc,

[thegreatestben]

Yep it does drop down to correctish Idle so I guess I need a new Valve.
Cheap or free plz

[frost]

have you tried the "spray carb cleaner around the intake gaskets to see if the idle rises" trick
oh oh and check coolant level and/or ecu water temp sensor,

[sergei]

Before buying new valve, just leave it filled with CRC over night and see if it helps.

[thegreatestben]

Before buying new valve, just leave it filled with CRC over night and see if it helps.

Have smashed it with crc and it's loosey goosey, its different to most types I've come across. Usually they are stepper motors that jam.
This one is magnetic and has a small butterfly inside it would seem. All moves nicely enough, just looking at the pic I can actually remove the magnet/switch/electronic gizmo part while its in place, I might take it off and turn the butterfly by hand and see if I can get it to idle right.

I did the spray carb cleaner thing too, everything else is sweet.
Error codes not coming up for anything except when I unplug the valve.

Also carb cleaner makes it splutter, you're thinking of engine start which increases engine speed

[frost]

yeah thats it, forgot what it was, i once mistakenly "cleaned" my isc with brake cleaner and it died, huh well seems brake cleaner is flammable but not combustible