Date: Sat, 15 May 2021 02:25:22 +0000
Reply-To: Richard Koerner <rjkinpb@SBCGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Richard Koerner <rjkinpb@SBCGLOBAL.NET>
Subject: Crummy Vanagon performance
Content-Type: text/plain; charset=UTF-8
Hey all,
A Vanagon owner in Canada is frustrated. To add to frustration, there are issues with posting things to Vanagon List and getting replies. I am here to help. So....I cut and pasted Gil's original message, and am posting, down below. I will do whatever I can to help, as a way to keep the conversation going back and forth. Gil is the guy's name.
Hi Folks,
I have a 1985 Westfalia GL original 1.9. I have owned it 18 years. Mileage
is uncertain as odometer was broken at 77,000km before I bought it.
I've been battling the Vanagon Syndrome for years not knowing it was a
"thing".
Basically it would lose power like it was out of gas and die somewhere on
the highway. We would either wait awhile and it would come back or it won't
start up again at all, and then we would tow it somewhere and get some
expensive repair done which may or may not have fixed it.
The last breakdown was in June 2020, 200km from home, and it was towed back
home and has been sitting in my garage since. Currently it starts nicely,
and idles well for a few minutes at about 900RPM, then idles rough, no
response on throttle, with high gasoline vapor in exhaust and loud
backfire. Attempting to drive stalls the vehicle.
Here's all the things that have been done in the last 2 years to try to
solve this by a local non-VW mechanic. My apologies for the long read!
Cylinders:
Test: Run Engine to operating temperature;
Remove Spark Plugs; Ground Ignition Coil output;
Inspect: Exhaust normal color during starting and running;
Measure compression at each Cylinder: 1: 105PSI;
2. 115PSI; 3. 110PSI; 4. 130PSI;
Place endoscope inside Cylinders and capture images;
Observation: Oil is not being burnt in the Combustion Chambers;
While the above measurements are low, the Engine should still run; No
abnormalities found in images;
Ignition System:
Inspect:
Spark Plugs: Found to exhibit electrode wear - replacement required;
Ignition Wires: Found damaged, patched with electrical tape - replacement
required;
Distributor Rotor and Cap: Found with arc burning on electrodes and
discoloration marks on sidewall after the electrode- replacement required;
Distributor Hall Sensor: Found with damaged connector - replacement
required; Ignition Coil:
Primary resistance: 0.83 - 0.14 = 0.69Ω - Range: 0.42 - 0.76;
Secondary resistance: 3053Ω - Range: 2400 - 3500; Throttle Idle Adjustment:
Found screw free of carbon build up;
Test:
Ensure the above findings do not exert undue influence upon testing;
Disconnect the Idle Stabilizer - as per client supplied manual; Unable to
start;
Reconnect the Idle Stabilizer;
Run Engine - difficult start with rough idle;
Inspect:
Extremely rough idle;
High gasoline vapor in exhaust, with violent backfire;
As Engine warms idle stability worsens until Engine stalls;
Observation:
Above may indicate weak spark due to Ignition Coil heating;
Repair:
Source, acquire, and install replacement Ignition Coil - Intermotor
018-1068-4 E534;
Test: Run Engine - difficult start with rough idle;
Observation:
Improvement minor;
Test: Capture ignition signals with oscilloscope;
Inspect:
Hall Sensor output malformed - slow rise time;
Ignition Coil output malformed - partial discharge at required time with
full
discharge shortly after;
Idle Stabilizer is functioning correctly by continually making adjustments
to correct
the above delayed Ignition Coil discharge;
Observation:
The above partial discharge is consistent with the marks found on the
Distributor
Cap side wall after the electrodes;
The malformed Hall Sensor output may cause failure to correctly trigger the
Ignition Coil Module;
Repair:
Source, acquire, and install:
Spark Plugs: ACDelco 194332132 - gap as per client supplied manual;
IgnitionWires: ACDelco89021012;
Distributor Hall Sensor: Intermotor LX538;
Install:
Distributor Rotor and Cap: Champion 18-0748-2 PTK1025 - client supplied;
Test:
Start and run Engine- difficult start with rough idle; Capture ignition
signals with oscilloscope;
Inspect:
Hall Sensor output improved - some slow rise time remains;
Ignition Coil output improved but remains malformed - lessened partial
discharge
at required time with full discharge shortly after;
Idle Stabilizer is functioning correctly by continually making adjustments
to correct
the above delayed Ignition Coil discharge;
Observation:
Hall Sensor providing better signal to ignition module;
Ignition Coil Module is not driving ignition coil correctly - replacement
required;
Repair:
Source, acquire, and install Ignition Coil Module - WVE 6H1020;
Test:
Start and run Engine - greatly improved start and idle;
Capture ignition signals with oscilloscope;
Inspect:
Hall Sensor output greatly improved - appears normal with sharp edges;
Ignition Coil output greatly improved - appears normal with square form;
Disconnect Idle Stabilizer;
Repair: Test:
Start and run Engine - greatly improved start and idle; Inspect:
Engine idles quite well without assistance of Idle Stabilizer;
Reconnect Idle Stabilizer;
Fuel System:
Inspect:
Temperature Sensors: Resistance within specification for cold Engine;
Above signals found at DCM connector;
Test: Run Engine to normal operating temperature;
Inspect:
Temperature Sensors: Resistance within specification for hot Engine;
Above signals found at DCM connector;
Observation: Temperature Sensors: Both are functioning normally;
Inspect: Oxygen Sensor: Found disconnected - reconnect;
Test: Run Engine to normal operating temperature;
Inspect:
Oxygen Sensor: Found to have alternating high/low output;
Above signal found at DCM connector;
Observation: Oxygen Sensor: Functioning normally;
Repair:
Vacuum lines: Found one failed.
Inspect:
Repair: Source, acquire, and install replacement line;
Repair: Remove Digijet Control Module (DCM);
Remove cover from DCM;
Remove Printed Circuit Board (PCB) from DCM;
Inspect:
DCM:
Component T402, power transistor, found with failed solder joint on output
terminal;
All other solder joints and connectors found good;
Observation:
Output of component T402 drives the Fuel Injectors - may be a source of weak
injection;
Repair:
Reheat failed solder joint on component T402 output terminal and apply fresh
solder;
Reassemble DCM and return to vehicle;
Test: Run Engine - no change in engine performance;
Repair: Disconnect fuel line from Fuel Pressure Regulator outlet;
Connect to pressure gauge;
Test:
Set Ignition to run without cranking Engine to run Fuel Pump;
Inspect:
Fuel pressure regulator found to be out of specification - replacement
recommended;
Repair:
Source, acquire, and install replacement Fuel Pressure Regulator;
Test: Run Engine - no change in engine performance;
Inspect:
Throttle:
Plate: Moves freely over full range and free of obstruction;
Control Cable: Moves freely over full range and free of binding; Idle
Switch: Operates as expected with correct signal to DCM;
Full Open Switch: Operates as expected with correct signal to DCM;
None.
Repair:
Inspect:
Air Flow Meter (AFM):
Flow Channels: Free of obstruction;
Measurement Gate: Moves freely over full range and free of binding;
Connector: Terminals on male and female sides found good;
Above signal found at DCM connector;
Test:
Run Engine;
Move Throttle to change Engine speed - Engine hesitates/stumbles immediately
above idle, change in signal from Throttle Idle Switch, and at partial
power;
Observation: Above indicates a signal integrity issue with AFM;
Test:
Run Engine;
Insert signal monitor onto AFM output;
Move Throttle to change Engine speed - Engine hesitates/stumbles immediately
above idle and at partial power;
Inspect:
AFM signal output drops to zero at immediately above idle and at partial
power coinciding with when Engine hesitates/stumbles;
Observation:
Above confirms a signal integrity issue with AFM - replacement required;
Repair:
Source replacement AFM - approximately $500 CAD and NOT available;
Remove AFM cover plate, non-destructively;
Inspect: Interior found clean and free of debris and corrosion;
Internal connections: Found good;
Potentiometer wiper moves freely and maintains contact with resistor; Wiper
pivot and slider contacts found good;
Test: Insert signal monitor onto AFM output;
Move Measurement Gate - AFM output unstable in two locations, likely
immediately above idle and at partial power;
Inspect:
AFM signal output drops to zero at immediately above idle and at partial
power coinciding with when Engine hesitates/stumbles;
Test:
Run Engine;
Move Throttle to change Engine speed - Engine hesitates/stumbles immediately
above idle and at partial power;
Inspect:
AFM signal output drops to zero at immediately above idle and at partial
power coinciding with when Engine hesitates/stumbles;
Note positions of above of potentiometer wiper upon resistor;
Stop Engine;
Test:
Inspect:
Potentiometer resistor found worn through at above wiper positions -
replacement required;
Repair:
Remove AFM from vehicle;
Source potentiometer resistor, Bourns 1288310051 - NOT available; Relocate
resistor so that wiper contacts move over unused resistive material;
Test: Attach signal monitor onto AFM output;
Move Measurement Gate - AFM output stable over full range; Repair:
Return AFM into vehicle;
Test:
Observation:
Above indicates that the AFM needs to be tuned for the changed resistance
characteristics due to moving the resistor and thus changing the wiper
contact area on such;
Tune:
With Engine running;
Change the wiper set point for idle;
Open Throttle to achieve high RPM;
Observe Exhaust for lean/rich;
Observe Oxygen Sensor for correct output;
Adjust spring tension;
Iterate the above, each adjustment affects the other, until satisfactory
performance
achieved at both idle and high RPM;
Test: Attach signal monitor onto AFM output;
Capture AFM output with Engine running;
Inspect: AFM output stable at all throttle positions;
Observation: Above has restored correct operation of the AFM;
Repair:
Ensure AFM cover plate and body are free of loose sealant;
Apply fresh sealant to cover plate;
Return cover plate upon body, ensuring sealant has filled all gaps;
Testing:
Driveability:
Engine starts reliably;
Engine idle is stable;
Engine RPM and power consistent with Throttle position - no
stumble/hesitation; Engine power good at speeds up to 70 km/h, limit of
testing;
Consistency: Engine operated very well for one 1 hour test drive;
Allow engine to completely cool;
Engine performance degraded as engine temperature approached normal on
second
test drive - retuned AFM;
Allow engine to completely cool;
Engine operated very well for third 0.5 hour test drive - check AFM;
Allow engine to completely cool;
Engine operated very well for fourth 0.5 hour drive to return vehicle to
client; (August 2020)
September 2020, again all the same symptoms have returned but worse. Van is
not able to drive beyond a few blocks without losing power and stalling.
May 2021: Soldered tantalum 15-22 capacitor to AFM and resealed with
silicone. Drained gas tank. Gas looks clear. Replaced with new fuel.
Van continues to sputter and backfire.
Any advice much appreciated!
