Good ol' CIS

[DeWitt Harrison]

While not as cool as the AAN boost issues being discussed, I dodged a CIS
bullet the other day. My MC engine suddenly lost the ability to idle
although, at first, I thought the engine had simply died from lack of fuel
or spark. But when it restarted OK a couple of times, I realized I just
needed to maintain enough throttle to keep the rpms up to get it back to
the barn.

It had been a long time time since I troubleshot this motor so I had to
clear out some mental cobwebs. So I looked at codes and then started
hooking up meters to look at idle stab. current, O2 sensor duty cycle and
such. While just kind of eyeballing stuff around the fuel metering head, I
noticed a little red plastic plug or cap just lying on top of the air
filter housing. Then it hit me: this must have fallen out of some hole in
the general area and - son of a gun - out of a hole in the big rubber
waffle boot above the air flow meter. And I quickly found it. Metered air
leak! Boy, could I have ever gone off into the weeds if I hadn't spotted
that.

The open port in the boot was probably something I had once deemed useless
and a reliability risk. I think it may have been the deceleration valve
stuff, part of the collection of weird gimmicks that comprise the turbo CIS
fuel system. (There is some irony here I believe.) I got the port properly
plugged and things tweaked a bit and all is well. Whew.

DeWitt Harrison
'88 5ktq