RE: 75 misbehavin'

[Lars Arvidsson <arvid@domain.elided>]

[David wrote]
A few questions remain in my mind, so please give me a moment more.
Did you find that the idle ever hunted up and down?
Would the kangarooing only happen when you tried to drive away?
Had you done a continuity test on the TPS?

[Lars replies]
Yes, the idle was hunting, but previously I've also found that the ICV
was sticking. (see below)
As long as the idle was 850 rpm +/- 200 rpm the idle was fairly stable,
but in severe cases,
often when cold outside (well below zero C) the idle valve got stuck at
wide open, and then the idle
was unstable. So that I blame the ICV.
And yes, the kangarooing only occured when driving. With shift in
neutral and pushing the throttle
the rev was pulsating, I think it's called "surging" in English.
Yes, I've tested the TPS several times, but never found anything
unusual.

[David wrote]
My feeling was that the idle switch is responsible for the hunting idle
in conjunction with a slow idle-speed-controller, but that the poor
running
you experienced is due to the rotors having lost their correct
resistance
due to the goo melting on the top of the rotor.  You said that you had
already soldiered up the wire in the 6 wire connector, so it can't be
that,
even though the symptoms are perfect!

[Lars replies]
Yes, the ICV is bad, it is stuck sometimes. washed out with WD-40, then
it works for a few weeks.
The WD-40 turns rust-coloured, wich is surprising since the ICV is
alloy. I guess the sealing to the magnet
parts is bad, and the magnet part ought to be made of iron.
I will replace both the ICV and the TPS.
My old rotors looked fine, but i replaced them due to wearage at the
spark-gap.
And I've soldered up the 6 wires this very weekend... earlier I've only
cleaned the connectors.


[David wrote]
When I cleaned my TPS some years back, it was rust that had caused
my problem, judging by the colour of the discharge.  I had a definite,
reproducible problem with continuity on the TPS at idle.  After WD40 it
was gone.

[Lars replies]
I wasn't able to take it apart without damaging the housing (maybe I'm a
coward...:-)  )
Did you find any signs of grease inside, that was supposed to be there?
I still wonder what it was, that coloured my WD-40...
How is the sealing at the throttle axis made? Is it a rubber ring? I
guess that moist from the intake
can find it's way down to the TPS. I keep asking myself is I have a
broken rubber sealing floating around inside the TPS...?
Btw, is there a full throttle switch inside the TPS as well? I've never
heard any "clik" from it. Maybe it's long since gone...

cheers, mate
Lars

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