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SlalomVan
Samba Member
Joined: March 28, 2006
Posts: 127
Location: Seattle, WA
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 Posted: Tue Apr 27, 2021 4:48 pm Post subject: Could it be "Vanagon Syndrome?" |
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I have a strange situation happening and I am reaching out here to the great minds on the Samba for thoughts and guidance. My Orly Blue 1988 (2.1l) Vanagon started exhibiting an intermittent engine stumble. The motor was rebuilt two years ago and starts right up, idles great and has been running really strong since the rebuild with no problems before this issue cropped up. It still runs great – except for the intermittent stumble. Is it “Vanagon Syndrome” I thought to myself. Nah, couldn’t be! City Streets, cruising on the freeway -doesn't matter. Happens at all different RPMS or speeds. Sometimes it is just a little hic-up, other times the motor dies and is hard to restart. I have spent hours researching and reading up, mostly here on the Samba, on what could possibly cause this issue. With a list of suspect parts and things to check, I started swapping them out one by one in an attempt to help isolate the issue. I have the luxury of having another great running Vanagon, my daily driver. So I know the parts are in good working order. No luck after a couple months of trying one thing after another.
Here is a list of the things I have either replaced with new parts or swapped out from my other Vanagon:
- Checked entire engine bay for vacuum leaks – all good.
- Ignition switch (new)
- Fuel Filter (new)
- Distributor/ Hall Sensor (swapped)
- Distributor Cap/Rotor (new
- Throttle Body Position Switch (adjusted and working)
- Fuel Injectors (swapped)
- Air Flow Meter / Airbox (swapped)
- Ground Straps – trans to body / engine to body (new)
- Fuel Pump Relays (swapped)
- Oxygen Sensor (unplugged – no difference)
- Idle Control Unit (swapped)
- GoWesty Signal Filter for Air Flow Meter (installed new as a last ditch – almost – effort)
Things I have not done yet:
- Installed New O2 Sensor
- Replaced Temp II sensor
- Replaced Fuel Pump
- Replaced Spark Plugs and Plug Wires
Looking for thoughts, ideas or advice on what next to try. Thanks in advance!
_________________
1989 Vanagon GL - 2.1 (White - "Northlake" Totaled/Gone)
1988 Vanagon GL Wolfsburg (Orly Blue - "Poulsbo" - Sold)
1989 Vanagon G - 2.1 (White - "Kingston") - Full rebuild underway - Last on the road in 1997 |
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32634
Location: Reading Pennsylvania
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Howesight
Samba Member
Joined: July 02, 2008
Posts: 3274
Location: Vancouver, B.C.
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| Posted: Tue Apr 27, 2021 5:05 pm Post subject: Re: Could it be "Vanagon Syndrome?" |
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I had a similar problem years ago when still running the WBX engine. It turned out that my ECU was malfunctioning due to a crack in the copper traces.
The Digifant ECU connects to the large connector via the Printed Circuit Board itself. The PCB is therefore subjected to whatever bending, twisting, pulling forces which the connector and cable exert on it. The ECU goes through temperature changes as well as it generates heat.
The hiccup problem arises from cracks in the copper traces on the PCB which can cause the ECU to "reboot" or similar mischief. The one notable marker of this PCB fault is that the tachometer needle very rapidly bounces to zero rpms and then back to the correct rpm's. Note that a faulty or intermittent hall sender in the distributor (usually failing in the wiring, not the sensor) can also cause this tachometer bounce.
One other possible cause that comes to mind for me is an ignition switch that has gone intermittent. These switches are cheap to buy and easy to replace.
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'86 Syncro Westy SVX |
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MarkWard
Samba Member
Joined: February 09, 2005
Posts: 17155
Location: Retired South Florida
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| Posted: Tue Apr 27, 2021 5:10 pm Post subject: Re: Could it be "Vanagon Syndrome?" |
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There’s a thread about converting the 5 prong relay in the engine compartment for a conventional 4 pin. I recall it powers the ECU. Don’t have the thread handy. Not sure of the year break either.
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32634
Location: Reading Pennsylvania
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4Gears4Tires
Samba Member
Joined: October 08, 2018
Posts: 3054
Location: MD
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| Posted: Tue Apr 27, 2021 5:36 pm Post subject: Re: Could it be "Vanagon Syndrome?" |
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I am chasing the same issue right now. In order of probability, some things you can try:
- Inspect your alternator wiring harness, unbolt it from the alternator and check the leads for cracks/broken insulation especially the blue wire
- Reflow the solder in the ECU with a soldering gun or baking it in your oven
- Check the temp2 sensor that it is fully seated and the contacts are clean
- Pull your plugs and note if any are black/wet/etc
- Verify spark plug gap when pulled, .028 is the spec
- Verify timing and when you do, see if the timing light drops light flashes when holding it at 2000rpm
- Adjust your valves
_________________
'87 Syncro
Ferric Oxyhydroxide Superleggera Edition |
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SlalomVan
Samba Member
Joined: March 28, 2006
Posts: 127
Location: Seattle, WA
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| Posted: Tue Apr 27, 2021 5:43 pm Post subject: Re: Could it be "Vanagon Syndrome?" |
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| djkeev wrote: |
Things you don't mention......
ECU ground wire?
Swap ECU's ?
Swap throttle bodies?
Spark plugs?
Plug wires?
Corroded 7 pin connector terminals in the firewall junction box
Wire from alternator to junction box? |
Forgot to mention in my list of things that I have tried:
- Swapped ECU
- Swapped Throttle Body
Next up I will check wiring to and from the alternator and the 7-pin connector in the box by the firewall.
Thanks, all!
_________________
1989 Vanagon GL - 2.1 (White - "Northlake" Totaled/Gone)
1988 Vanagon GL Wolfsburg (Orly Blue - "Poulsbo" - Sold)
1989 Vanagon G - 2.1 (White - "Kingston") - Full rebuild underway - Last on the road in 1997 |
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32634
Location: Reading Pennsylvania
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4Gears4Tires
Samba Member
Joined: October 08, 2018
Posts: 3054
Location: MD
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| Posted: Tue Apr 27, 2021 5:54 pm Post subject: Re: Could it be "Vanagon Syndrome?" |
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Also, several people have had success with mounting the ECU upside down. This closes the stress cracks. You will have to drill new mounting holes.
_________________
'87 Syncro
Ferric Oxyhydroxide Superleggera Edition |
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SlalomVan
Samba Member
Joined: March 28, 2006
Posts: 127
Location: Seattle, WA
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| Posted: Tue Apr 27, 2021 5:54 pm Post subject: Re: Could it be "Vanagon Syndrome?" |
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| djkeev wrote: |
First pull your relay. Is it five pin?
Do the easy relay modification outlined first.
It will do no harm, might just fix your Van.
My early 90 now has the four pin relay.
Dave |
I will try that first!
Thanks, Dave!
BTW - love your thread on your recent (and previous) engine builds! Gave me the courage to do mine. Now i'm on to my third rebuild. 
_________________
1989 Vanagon GL - 2.1 (White - "Northlake" Totaled/Gone)
1988 Vanagon GL Wolfsburg (Orly Blue - "Poulsbo" - Sold)
1989 Vanagon G - 2.1 (White - "Kingston") - Full rebuild underway - Last on the road in 1997 |
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SurfaceRust
Samba Member
Joined: January 24, 2016
Posts: 160
Location: Los Angeles
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| Posted: Wed Apr 28, 2021 2:47 am Post subject: Re: Could it be "Vanagon Syndrome?" |
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How old is your battery?
I'd add to the list to check or have a auto parts store check the battery and alternator. |
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SlalomVan
Samba Member
Joined: March 28, 2006
Posts: 127
Location: Seattle, WA
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| Posted: Mon May 17, 2021 10:38 am Post subject: Re: UPDATE: Could it be "Vanagon Syndrome?" |
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| SlalomVan wrote: |
I have a strange situation happening and I am reaching out here to the great minds on the Samba for thoughts and guidance. My Orly Blue 1988 (2.1l) Vanagon started exhibiting an intermittent engine stumble. The motor was rebuilt two years ago and starts right up, idles great and has been running really strong since the rebuild with no problems before this issue cropped up. It still runs great – except for the intermittent stumble. Is it “Vanagon Syndrome” I thought to myself. Nah, couldn’t be! City Streets, cruising on the freeway -doesn't matter. Happens at all different RPMS or speeds. Sometimes it is just a little hic-up, other times the motor dies and is hard to restart. I have spent hours researching and reading up, mostly here on the Samba, on what could possibly cause this issue. With a list of suspect parts and things to check, I started swapping them out one by one in an attempt to help isolate the issue. I have the luxury of having another great running Vanagon, my daily driver. So I know the parts are in good working order. No luck after a couple months of trying one thing after another.
Here is a list of the things I have either replaced with new parts or swapped out from my other Vanagon:
- Checked entire engine bay for vacuum leaks – all good.
- Ignition switch (new)
- Fuel Filter (new)
- Distributor/ Hall Sensor (swapped)
- Distributor Cap/Rotor (new)
- Throttle Body Position Switch (adjusted and working)
- Fuel Injectors (swapped)
- Air Flow Meter / Airbox (swapped)
- Ground Straps – trans to body / engine to body (new)
- Fuel Pump Relays (swapped)
- Oxygen Sensor (unplugged – no difference)
- Idle Control Unit (swapped)
- GoWesty Signal Filter for Air Flow Meter (installed new as a last ditch – almost – effort)
Things I have not done yet:
- Installed New O2 Sensor
- Replaced Temp II sensor
- Replaced Fuel Pump
- Replaced Spark Plugs and Plug Wires
Looking for thoughts, ideas or advice on what next to try. Thanks in advance!
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UPDATE: Check ALL your grounds! Thanks to everyone for all the great input! After going through all of your suggestions and double checking, sometimes triple checking all the possible culprits, there was just one thing that I neglected to check. The small ground wire that comes out of the main harness where it connects to the ECU! I never checked this when I previously swapped out the ECU. Sure enough, both the connector and the post it fastens on to had oxidized and completely turned green. Took a wire brush to them and cleaned them up so they were nice and shiny. Even though this wire is inside the van and protected from the elements, it had oxidized to the point is was no longer doing its job all the time.
Intermittent problems are the hardest to diagnose and chase down. This issue really had me puzzled. I now have a couple hundred miles on the van since this simple fix and - no more stuttering!
Having gone through all the different scenarios and possible culprits that could have been causing the stutter was not a waste of time no matter how frustrating it was. I now know the van that much better and am more confident in my diagnosis skills.
Thanks again to the collective brain trust for all your help!
_________________
1989 Vanagon GL - 2.1 (White - "Northlake" Totaled/Gone)
1988 Vanagon GL Wolfsburg (Orly Blue - "Poulsbo" - Sold)
1989 Vanagon G - 2.1 (White - "Kingston") - Full rebuild underway - Last on the road in 1997 |
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