idle issues with '87 4kq, THERE BACK!

[Luke Rickert]

With the archive search engine MIA I am forced to bring up a topic which
has surely already been well addressed. I apologize. 

I sent a message out a couple of weeks back about idle stability
problems during cold start-up for my '87 4kq.  Since then I have cleaned
the ISV, checked and replaced both of the temp sensors in the upper
flange, replaced the O2 sensor, and checked the idle switch.  I cleaned
the ISV first which partially alleviated the symptoms, the other work
didn't make any noticible change to the cold idle.  The probelm was
partially mitigated until Saturday night when I tried to go watch the
final F1 race, the car returned to the same large oscillations as before
I did anything. It happenend again last night but today when I went out
to test it, everything worked as it had after the initial ISV cleaning. 

Given that I have the problem at night, when it is cooler than the day I
suspect a temperature related problem, perhaps the idle position switch.
I am considering removing the idle switch and seeing if it still works
after spending some quality time in the freezer. Unfortunately, the
switch in question does not look like it is going to come out very
easily, so I would like to be fairly certain that it is guilty before
removing it. 

Are there any theories out there? I am going to go test the switch again
tonight and see if it works.  I should probably also go pull the
controller from under the dash and test the ISV, I know that it is
getting power, but not much else.   One more point, I do get a little
bit of "dieseling" when I shut down, which according to the manual can
be caused by a leaking ISV. 

thanks for the help

luke 


--- 
Luke Rickert
www.engr.orst.edu/~rickert