Date: Wed, 5 Mar 2008 20:42:59 -0800
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: Still running like crap, the saga continues
In-Reply-To: <Pine.LNX.4.58.0803051938450.12563@kenneke.com>
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I would so love to write the definitive troubleshooting steps.
I can not say enough 'check the basics.'
Like pretend I wrote that 5 times always, always check basics really
carefully first - like compression, fuel pressure, inspect spark plugs etc.
Btw...there's an old time rule ( I've been working on cars of all types 44
years or so ) ..it came from the carb days, but it still applies :
( this is for gasoline, not diesel of course )
Mechanical condition of the engine first ( compression, valve timing,
timing belt if that applies, ....everything that is mechanical with the
engine.
Next - everything ignition. Like make sure that is rock solid.
Spark plug wires btw - they can be VERY nebulous - it they are old, or
cheap...you can work on a car for days and in the end it'll be spark plug
wires that were 'the thing' - some tricks - watch the engine run in total
darkness, you see tiny sparks running around - bad plug wires.
Another back yard spark plug wire test- light spray them with water while
it's idling, if it stumbles, bad plug wires.
Coils - coils don't usally fail. They just get old. I put a new coil on a
fine running personal car of mine one time - it ran 15 % better, and I
thought it was fine before that.
THEN fuel system.
Also, since it's electronic, this can't be said enough :
grounds, grounds, GROUNDS.
Electronics can be nebulous too. The actual electronic components are very
robust usually, like the ECU. I seldom find a bad one.
But how the wires contact, or how the wires themselves are- wires get old,
grounds corrode.
Here's another 'rule' :
This is a Scott Foss-original ( that's me, Scott Daniel Foss ) 'Rule' -
WHERE ANYTHING MECHANICAL INTERFACES WITH SOMETHING ELECTRICAL OR ELECTRONIC
- that's a weak area .
Points are an example. A phonograph needle is an example.
Switches arcing and wearing are an example.
So.....the biggest mechanical/electronic/electrical interface in a vanagon
is the Air Flow Meter.
Moving parts, and a mechanical sweeper, like a fuel gauge sender - it can't
work indefinitely- though they do hang in there well. Its mickey mouse in
modern times even.
It's a weak link.
All modern cars have an air mass meter, no moving parts- a huge leap forward
in about 3 ways over an AFM. Compensates for humidity, barometric pressure,
etc. - an AFM can't do anything like that - it's very dumb in comparison.
Plus it has a mechanical sweeper that wears. There's a trick about
rebending the sweeper to contact a different area of what I rubs on. The
spring tension on it is adjustable somewhat in some AFM's but that's not
something you'd ever change. It's not recommended to go messing around in
there. They're a bit sensitive, and if tired, they're just tired. Best is to
have a couple good used ones to play with.
(to give you an AFM story- had this customer's 87 syncro- at right around
3.200 rpm it would not quite miss or stumble, but it was uneven. Many people
wouldn't' notice it. I noticed that the way the power curve and gearing
was, you always ended up driving it form 3,000 to 3,500 rpm, and often right
at 3,100 to 3,200 rpm.
I was hesitant about a 500 dollar AFM,, but we found other major reasons for
vibrations decelerating from 52 mph, and the customer just like to invest
money in it, and we ended up doing a rebuilt trans, repairing a broken off
engine mounting stud, a clutch, a driveshaft, and a starter and after all
that, hey, why not an AFM too, right ? And it ran dead perfect after that.
The AFM was worn and faulty. )
Also....back to the 'it's a blockage of fluids or electrons' - check your
air intake boot. Those last really well too, but need to make sure that's
not it.
Exhaust leaks 'don't usually' make an engine run incorrectly., They can for
sure, but it's not like 'if it has exhaust port leaks it can't run right' -
it can run fine with those, but of course, false air-exhaust to the O2 can
throw it off.
And....02 is not involved in starting and WOT ( wide open throttle ),
Though I've read about people finding a shorted 02 wire as 'the cause' of
poor running - and that would make the ECU stumble.
( Never have encountered that myself, but it's possible. )
And there are a lot of checks in Bentley to do too.
Resistance checks.
Also....coolant temp sensor - SO MANY times hard starting or dodgey running
has been traced to poor connection to one of those.
Can't say that enough either.
So that's all needed - the orderly procedure of testing starting from the
basics, like maybe 40 to 50 inspections and tests.
And then these 'rules' .
And some things you simply can not test, like an ECU, other than to try it
in another vanagon, or put a known good one in yours.
I get all the components 'extra' at pick n' pull junkyards, try them right
away, and if they're good, I put a number on them, so I know if I'm running
# 1 or # 2 ECU or fuel pump, etc.
\They're easy to fix - lol.
Scott
www.turbovans.com <http://www.turbovans.com/>
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
jon
Sent: Wednesday, March 05, 2008 8:00 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Still running like crap, the saga continues
See comments, below:
> OK, since the throttle body is a known area where it could be leaking I
> guess I should start with this. I've never taken one off. Is it pretty
self
> explanatory like R & R of the AFM or do I need the Bentley procedures?
What
> exactly do I fix once I get it off?
The throttle body proper is easy to remove: once you remove the air filter
assembly, unlpug the AFM and remove it's hose clamp. Then, to remove the
throttle body (I assume you are referring to the unit proper, not the
intake manifold), remove the throttle cable, two hoses, and the vacuum
hose.
Is it leaking from the boot, or the metal body itself?
> That exhaust check will be next after this.
That makes a huge difference. And, like other folks said, check your cat.
as well.
> Fuel pump and filter are 6 months old the fuel pump went out one day with
my
> 3 year old. Luckily we were in walking distance of the house. I have a
> bottle of injector cleaner in the tank that I added right now. The fact
that
> moving screws around, timing, etc. is affecting this kinda makes me think
> it's not the injectors.
Good.
> BTW, what would be great would be one of the list mechanics starting a
> "virtual repair center". The idiot at one end (that would be me) could
move
> the PC camera around while the real mechanic on the other end does the
> guiding as to what steps to do for repairs. Just rambling.....
Wow. Since I'm a very confirmed shade-tree mechanic, I'll will not be
participating in that venture! ;)
Jon
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