Date:         Mon, 17 May 2021 11:32:02 -0600
Reply-To:     Gil Ngai <eyebawlgil@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Gil Ngai <eyebawlgil@GMAIL.COM>
Subject:      Re: Crummy Vanagon performance
In-Reply-To:  <CAB2RwfgAWAkrZ7ORB8hHSqqbmoSzx9T5MigO6nunRz67Kavsxg@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

Hi Everyone,

Thanks for all your input! I think I am getting the emails but who knows
for sure.
I do see your comments Neil, thanks!
To confirm I do have a new fuel tank, fuel lines, square fuel filter.

Dennis, here are responses to your comments from my mechanical friend Ron:
---------------------------------------------------------------------------

*From Dennis:*

Since it starts and runs OK cold most things are close enough to run.

Yes.  Otherwise the effort to undertake repair would not have been
attempted and a recommendation to proceed directly to replace engine would
have been made.

So part of the diagnose is to look at tings that change after warm up. If
truly going rich after warm up the next steps

Yes.  This was observed after starting issue was corrected.

I take are to look at the temp 2 circuit

Yes.  Verified signal as expected at both cold and hot engine temperature
and observed at both sensor output terminal and Electronic Control Unit
(ECU).

and O2 Sensor circuit.

Yes.  Verified signal as observed at both sensor output terminal and
Electronic Control Unit (ECU).

On the 1.9L the O2 sensor is not as reactive as the 2.1L but still it can
cause some grief.

The observed signal varied as expected for an O2 sensor.

The temps 2 and O2 sensor inputs relay heavily on proper ground reference.

Yes.  O2 and Temp 1 and 2 are low level signals that are transmitted over
single conductors, which is extremely prone to reference (ground in this
case) instability.

Check for stray voltages on the O2 sensor wire outer sheath

Yes.  None observed.

and the ground side of the temp 2 sensor.

Yes.  None observed.

Also make sure the inner signal wire for the O2 sensor is not grounded.

Yes.  Verified signal wire intact and isolated from ground.

Be prepared that you can have broken wires inside the insulation and
defects in the harness.

Yes.  This would be an intermittent.  But as it does not present when
engine is cold lessens this possibility.

Resist the temptation to just clean all the grounds.

Yes.  All grounds were carefully cleaned.  Very carefully!

The more you blindly touch the more broken wires and failed connections you
can have.

Yes.  A prime reason the Bostig option is superior.

Diagnose as much as possible in place.

Yes.  Done before attempting electrical wiring work.

For aggressive cleaning

Yes.  Removal of corrosion does NOT require aggressive mechanical removal.

or sanding terminals

Yes.  Very fine grit and used abrasive applied.

consider that all quality terminals have a surface finish

Yes.  Abrasive action applied to only remove corrosion - with some surface
finish remaining.  If no finish remains, then terminal would be replaced.

to maximize contact

Yes.  Ensure electrical contact surfaces are clean.

and some type of coating or plating to control corrosion.

Yes.  See previous comment.

They also were not designed for 4 decades of service.

Yes.

If needed carefully replace with quality stuff, sealed connections to stop
further corrosion of the wire and good crimping tools.

Yes.  If replacement is needed, then quality parts and correct tools are
used.


While probably not the cause of shut down situations the poor engine health
can be a contributing factor.

Yes.  What testing beyond compression test, as specified in the Bentley
manual, is useful?

The fuel management relies on a number of assumptions.

Yes.  This was discovered.  The ECU is not much of a control system.  It
merely accepts available inputs, uses inputs to look up values in a stored
table, and outputs the look up values to fuel system mechanical
components.  It is apparent that there is no validation of inputs nor
compensation for when inputs may be suspect which results in outputs that
cause poor performance.

Bad intake valves and worn guides present the same problems as vacuum leaks
with the addition of burning combustion gasses.

Yes.  How would this manifest in a compression test?  Hot/cold engine?

Think of stuck EGR valves on other vehicles. This combination can give
faulty reading to the O2 sensor and cause it to way out either rich or
lean.

Clarify.  Not clear on what the combination is nor how such might affect
the exhaust gas composition at the O2 sensor.

Same for leaking valve covers.

Yes.  No leaks observed.  Would this manifest so strongly between cold and
hot engine?

Also make sure the exhaust is tight. If exhaust is getting out then outside
air is getting in. Fresh air in the exhaust, drive the engine richer.

No.  The exhaust is pressurized, which would prevent fresh air from
entering the exhaust stream.  Unless there is a gross exhaust piping wall
failure upstream of the O2 sensor - none observed.

Back firing, the fuel is igniting in the exhaust, not the cylinders.

Yes.  BANG!!!  Good thing for PPE!  Backfiring was greatly reduced, almost
eliminated, after rebuilding the Air Flow Meter (AFM).


Some of the parts choices are also questionable.

No.  Assumption that the domestic parts used are of lower quality is not
the case.  Parts were selected, inspected, and found to be of excellent
quality - low price was NOT used as a positive selection criterion.  Low
price parts are disqualified from consideration.

For spark plugs you want to only use plugs that are nickel plated.

Yes.  ACDelco spark plugs used are plated for corrosion protection and
cylinder head thread protection.  Further, spark plug threads, regardless
of brand, are inspected for damage and corrected as necessary.

The black oxide ones will at some point take the threads out of the heads.

Yes.  Corrosion protection plugs used with light application of quality
anti-seize, and correct use of torque wrench to apply specified torque -
cylinder head threads are safe!

Distributor cap and rotor, Bosch only.

The distributor cap and rotor were acquired while on a trip.  Thus,
selection was based primarily upon availability.  Regardless, the Champion
cap is of good quality:  Finish, electrodes, and terminals; and the rotor
is of good quality:  Finish, electrodes, terminals, and integrated resistor
within specification.



























































•••••••••••••••••••••••••••••••••••••••••••••••
*GIL NGAI* • *I TELL GOOD STORIES*
*cinematographer • **chief storyteller • instructor*
* www.dayonemedia.ca <http://www.dayone-media.com/> *

>
>