Date: Sun, 3 Nov 2002 12:57:23 -0800
Reply-To: Doktor Tim <doktortim@ROCKISLAND.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Doktor Tim <doktortim@ROCKISLAND.COM>
Subject: Re: YAHOOOO (well, almost)
In-Reply-To: <NBBBLKPACPEEKLBIBDMMKECPFCAA.laurence@alanasmith.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 08:11 AM 11/03/2002, you wrote:
>Hard to beleive isn't it? One small ground wire can cause so much
>frustration and expense.
The opening paragraphs of the FI section in Bentley clearly states
verifying no vacuum leaks, no ignition problems, then verify grounds and
terminals BEFORE attempting diagnosis of the FI system components. Then
next comes verifying the fuel pump and pressure regulator. You can't skip
that just cause you don't want to buy a gauge. Then and only then are you
ready to start diagnosis of the Black Box and everything else hooked up to
it. When you skip steps in the procedures you are not following procedure.
Not following procedure is the way to waste the most money until you go
back and confirm the skipped steps.
And guess what, before any of that, you must know compression balance.
That's why the engine system comes before the FI section in Bentley. Did a
first time inspection of engine on a Vanagon last week. They had had the
"tune up" and it just wasn't running right. Within the last 2 years
maintenance history showed, new plugs, then a month later new wires. Full
history of 91 Vanagon shows no brake fluid renewals, no full coolant
replacement ever, a not one compression test.
I pull the plugs and at 15k they have more than 0.2mm wear, but all are
clean. Warm compression balance shows 150/123/136/149. Spec is 118 min not
more than 44lbs variance. I am in spec but barely. Wire connectors at the
plugs were all coated an even green with corrosive crusts. New plugs and
new wires with dielectric grease for everything. Hook up to watch oxy flux
at 0.1 to 0.9 volt. Because I have the compression test, I know this is
corraboration of the range of the FI system adjustment being exceeded,
confirmation of the proper system response and operation, and don't spend
the next hour or two wondering what else might be wrong. Ergo, idle is
starting to hunt a bit because the exhaust is being contaminated by poor
combustion in one cylinder.
So, new plugs were put in with corroded terminals, then new wires were put
on and contaminated the new terminals, and a year later they come to me. In
the end, the cause was not poor spark, though that would have become a
problem sometime sooner rather than later.
There is no need to be buying a bunch of FI parts with money that should be
reserved for a rebuilt motor or the tools needed for the next proper step.
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