(08-31-2019, 11:31 AM)tmanstein Wrote: New here
Got here because I had a fast idle, figured out it was a rat chewed vacuum hose. While researching I removed and cleaned the ISC and replaced the gasket. After putting all back together here is what I have:
Cold Start - 1200rpms down to 700-750.
Hot Start - 600 working up to 700-750.
This is great compared to what it was 2000cold 1600hot, so fixed the big problem but get this.
In doing the test that FixKick describes, I can remove the electrical plug to the ISC with no change at all. I can also plug the air inlet to the ISC with no change at all. If I read correctly it should stall/drop to 400. Am I digging too deep or do I have a problem?
1994 Sidekick 4dr, 5spd, 16Valve Gen1(I think, see pic)
Thanks in advance
Tman
1994, 8 valve engine? or 16valves. what transmission? M/T or A/T?
the (8v sure does race idle too fast for any vacuum link from any source and vast possible)
1200rpm cold is only controlled by the IAC thermal controller in the base of 8v TB ,or the 16 is v the IAC bolted to bottom OF TB. very differently but works same. so that was all normal.
IAC is the cold engine idle controller. ISC electric is hot controls.
hot RPM is 800 RPM only +-50rpm so 750 to 850 is normal and regulates there, ECU does regulation of it.
when you remove that ISC plug , the valve must closed 100% and that will cause huge RPM drop if not, the the ISC is not working at all.
ISC test 101:
hot engine 180f or more.
idle 800 is normal. never 600 ever. HOT engine.
turn on Head lamps and heater fan (not AC) at same time. and see RPM hold at 800 RPM, this proves ISC works and regulates. it can take a second or to to catch up and hold 800. but will regulate.
if automatic trans, shifting to DRIVE from park RPM holds at 800, or ISC is dead. if it falls far.
http://www.fixkick.com