04-22-2019, 05:20 AM
(04-22-2019, 04:59 AM)fixkick Wrote: hello Tquick;
yes these old cars are very hard to diagnose until 1996.
G16A TBi ENGINE.
1100 RPM MEANS VACUUM LEAKS, (LOTS OF PATH , LEGIT AND NOT)
THE ISC IS PWM MODULATED 100 TIMES A SECOND.
There are vast kinds of voltmters for 50 + years, even DMM meters many will see that 200Hz square wave as 0volts (blind to AC it is) scope sees truth never any dmm but say RMS meter.
hard starting and bad hot idle.
well are the spark parts fresh plugs wires and cap ./rotor or 25 year old.?
the IAC adds air cold , the ISC im not sure cold it is a hot running device, but may be open 50% at cold start.
The IAC air must happen or the engine wants to flood.
IAC is thermal in the base of the TB under 3 tiny screws (and cap)
isc signal some dmm show 7v 1/2 of alternator voltage others 0 or any wild thing, 7vdc is averaging of a square wave.
http://www.fixkick.com/IDLE-AIR/iac-wave1w.jpg
the ISC is here. pin B14, the other end of ISC is battery voltage (lite-green/red) lite-green-white wire is modulated by the ECU 200 times a second.
http://www.fixkick.com/INJECTORS/89/89-90schem1.jpg
I should say it runs great and idles smooth when warm but it does stay around the 1100 mark, but is it possible that the tach in not accurate?