Date: Fri, 24 Nov 95 18:32:08 0800
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: Steve Hoge <steveh@emu.com>
Subject: Throttle Switch Thrombosis
Isn't fuel injection FUN?
OK, the latest on my Digifant-equipped '89 Syncro is that I'm getting
an incredible surge/lag effect as I accelerate/decelerate. Touching
the gas causes it to accelerate (smoothly, and with good power), and
letting my foot off causes it to instantly and dramatically
decelerate. When cruising at speed on the freeway, where the car
should be subtely balanced between the two, say around 3000rpm, it
can get into a violent oscillation and shuddering effect - very
scary.
I don't think it's related to the bad gas I got a couple of weeks ago
(see the Techron posts), but it *did* start to happen pretty soon
(but not immediately...) after I cleaned the Panamint dust out of my
engine compartment with the hose (I took the precaution, suggested
by a correspondent, of unplugging the distributor and covering it
with a plastic bag, but otherwise pretty much sprayed all around.)
According to my reading of Bentley, this surge/lag is the same affect
that I should see if the throttle switch gap is too big (ie, >
.01mm). However, I can't see how moisture in the engine compartment
could have affected this clearance. Unplugging, cleaning and
reseating the connector between the throttle valve switch and the ECU
(done at midnight under a streetlamp...) *seemed* to help for awhile,
but the effect eventually returned.
Is it possible that I've toasted my throttle valve switch? Water in
there somewhere making intermittent contact? How expensive are these
parts? Of course, Bentley makes disassembly look easy but in reality
it's wedged beneath manifolds, my (non-functioning) cruise control
stuff, etc.:-P Also, I believe I'd have to do a idle recalibration
after reassembly, no?
A larger question: is there any "Idiot's Guide to Bosch Fuel
Injection Systems" out there that I could read to get better theory
of operation on my FI system? I've perused our FAQs and there're
lots of good details on FI but I didn't exactly come up with a global
overview of the system. Anything short of enrolling in a German
technical institute to get a better understanding of this stuff?
Steve Hoge
'77 AutoLoaf (Da Rust Bucket)
'89 Syncro GL (Da Shudder Bucket)
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