Next question: idle speed

[rudar]

So I think amongst all other problems on my 1991 MT 8v tracker, the idle speed's a bit high. It hovers around 1000-1200rmp by the tach on the instrument cluster, and when first starting, it races up to 2500 for a few seconds, which seems excessive.

The procedure for checking it, according to Chilton, which seems the best manual I have access to, involves hooking a Duty Meter (which I don't have) to the DC-DLC, and then detaching the noise suppressor connector and attaching Suzuki Adapter wire (or equivalent specific tool) between the suppresser and the detached connector, and attaching the tachometer to the adapter wire...

A duty meter I imagine I can find, hopefully cheap. But what the heck is that adapter wire or equivalent, and how would I get my grubby paws on one? Or are those instructions obsoleted by today's fancier dwell-tach meters, and I should follow the instructions that came with the meter (which, of course, I can't find...)

[rudar]

Pondering this over coffee this morning: Could a dwell meter double as a duty meter? Isn't that essentially what it's measuring? As in, 45* of dwell on the 4-banger scale would be the same as 50% duty cycle?

[jtgh]

those are all good questions.
yours is just like mine so I can help you.
assuming someone didn't bugger the screw on the butterfly valve you are good.
don't touch that white painted screw.

first off, your check engine lite must be on at key on, no start and off when running.?/?
this is important, as some failures , block the ECU idle features. (with IAC)
ok assume all is good.

you have the hidden bleed screw on air horn, use it to set hot idle. see my photos.

if you dont have air leaks ,just adjust this bleed.
if cold is too fast,
then adjust IAC 5mm screw at its end.
it is a tricky triple compromise here, bleed , iac, and 50% DC.


see last photo for location.
fresh-air for start and idle

fast idle page.
racings-or-highIdle


keep in mind 8v always race to fast, for any illegal air leak. Tis normal for leaks.
cracked hose, etc.

Now the Duty cycle .
ignore that tach connection use dash tach, or a IR tach like i have.
then hook any volt meter to IAC wires (backprobing with needles)
so 50 % is 1 half of 14.7v running voltage.
round to 15 volts , divide by 2 get , 7.5v
so do the setting as stated for 7.5v on the meter.
it is really a square wave that signal so when it is hi for 1/2 the time and then low for half the time, you get 50% of alternator out put. see?
the special meter is not needed and in newer manuals they explain this method better.

one last trick see that dash pot on the throttle body back side.
it will hold the idle high as you start car and then after a few seconds after start, it must fully retract and NOT touch the throttle crank.
if it does not do exatly that , it is bad. ( it has a hidden spring inside)
let me know how you do.

all the DC stuff is just show ECU can raise the idle hi or low by same about, around 800 rpm ( you are centering its command authority)