Stumble/miss/hesitate Was: 82 wiring diagram PDF needed...

[mk1mark at gmail.com (Mark F.)]

On 9/30/06, Karl Krupke <kkrup62@hotmail.com> wrote:
> Heya,
>     Yeah, as Cathy says just because you've replaced a component don't
> assume the new one is good, not always the case unfortuneatly.


The distributor only has about 10,000 miles on it, so I'm looking
elsewhere first, but Murphy's Law might have something to say about
that theory...  :)


> As much as
> possible try to isolate components, test for function one at a time,
> systematically. Time consuming and rewards are slow, but it's the only way
> to track down some problems.


That's basically the way I'm going about it.  A nasty flu this week
kept me from troubleshooting, but I'll be back at it again tomorrow...


>     Also, from your description, I start hearing this little voice in back
> of brain saying "Vacuum leak". A cracked boot might appear and feel intact,
> but under load or acceleration, when the engine pushes against the mounts
> the boot will flex and open up. It can be cyclic, in that you make a leak,
> the engine coughs and the flex reduces; now the engine has good flow and you
> start the cycle again. Hope that makes sense...


I just put this engine together less than two months ago, and was
pretty anal about putting all my best parts on it (including the
rubber bits).  My first guess was a vacuum leak as well, so I
thoroughly checked every component that could be leaking (including
spraying ether around them) and I am confident there are no vacuum
leaks.  The fact that it consistently runs fine for the first 10
seconds or so (a bit longer on colder mornings), rather than a more
random problem also points to something else...

It might be the swapped in knock box (from an 86 GLI), since it taps
into engine vacuum to determine load (changing load on the engine
seems to exaggerate the problem).  I'm going to try my friend Sean's
knock box tomorrow since that's a quick two minute procedure...

To me it seems like the engine is getting a weak or improperly timed
spark.  The fact that it ran ok for a day after I put new plugs and
wires on it points to a spark issue, but who knows, maybe that was
just a coincidence.  When building this car up I discovered many
electrical problems, and the fuse box area is quite warm when running,
so I may also swap in another fuse box for the hell of it...

If it's a fuel issue it could be the fuel pump - which might explain
why it runs good initially until the pump quickly overheats...  I
should also check the screen at the fuel pressure regulator for a
buildup of crap.  The car sat for a while before I resurrected it,
which doesn't help...

Arrrrggggg...  I hate problems like this.  It's much easier if you
have NO spark, or NO fuel...

Later,

Mark.
75
82
82 Caddy