Is this typical " vanagon syndrome "?

[Lufti]

86 single cab 2.1 manual trans.

Starts and runs great while cold then no throttle response, farts, pops and dies...

I've got a well running 87 westy with no current issues that I've been swapping parts to and from to test the AFM, idle relay, the ECU and blue thermo sensor. These items were put in individually, ran the engine then at the end of the day of course I shot gunned everything in for a hail-Mary with the same result.

Tried running with and without the O2 sensor, no difference. New fuel filters, new fuel pressure regulator, known good fuel pump.

All electrical connectors have been cleaned up, no broken wires found, new engine ground strap.

To me, the issue is the signal being sent from the blue sensor once its out of the cold-start loop. A new sensor hasn't helped. Swapping the ECU didn't magically cure anything either.

Does the other temp sensor ( forward of the thermostat ) communicate with the ECU? It's my understanding it is just for the temp gauge.

I'm borrowing a VAG whip that supposedly cures vanagon syndrome as my next step but damned as both my AFMs work great in the Westy.

Engine has 135 to 140 psi comp all around, no coolant leaks or cracks in the heads. While it runs, it runs great.

If I'm not chasing a failed component then it must be 25 year old wiring ?

Mildly frustrated, stubbornly not giving up.

Any thought folks?

[vanagonjr]

Vanagon syndrome, at least how I experienced it on my 86, occurs after a steady state cruise for an extended time. It's a fairly violent bucking as if the power is being switch on and off. (I got a used factory harness and it cured it.)

Shutting off the engine and a restart cured it temporarily for me on the day I experienced it. I got the repalcement harness the next day.
_________________
John - 86 Wolfsburg Westfalia "Weekender"
Flint reversed 1.8T W/Passat 5-Speed
LiMBO (late model bus club) www.limbobus.org
LiMBO is on Facebook too! https://www.facebook.com/groups/
FAQ thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=525798

[crazyvwvanman]

There is a special ground wire that branches from the small bundle of wires that go to the side of the distributor. This brown wire is VERY important in closed loop operation after the engine is warm. Find this brown wire, make sure this brown wire is in good condition and PUT A NEW END on it and attach the new end to clean bare metal on the engine!

Hope that helps.

Mark

[Lufti]

Replacing the engine-ECU wiring harness sounds like the next logical step! Good, good times.

[dspieg]

Recently when I was experiencing General Vanagon Weirdness (GVW),and following months of questions, suggestions, troubleshooting, random parts replacement and much scratching of the head, my problem turned out to be nothing more than..................an intermittently bad coil.

So my suggestion is to replace your coil, it's cheap and easy and you will have eliminated one possible cause.

Ref: My thread "Not-Quite Vanagon Syndrome" or something like that.

[randywebb]

[crazyvwvanman]

That picture does not show the small bundle that goes to the side of the distributor.

Mark

[randywebb]

[crazyvwvanman]

Does the braided cable look what what would be called a brown wire?

Mark

[snowsyncro]

[randywebb]

thx, but I see 2 squarish black connectors in that pic

the bottom arrow points to one that is just to the left of, and slightly behind the distributor

the top arrow points to one that is a bit further to the left and in front of the distributor

which is which?

_________________
1986 2.1L Westy 2wd Auto Trans.

[snowsyncro]

Sorry, I meant it is in front of the distributor, in the picture, not in the van. I can see the confusion. It is the bottom arrow.

RonC

[randywebb]

thx - here is a better pic

I think it must be the brown wire that goes over to the left and is bolted to the case along with that braided cable.


also I did the search you suggested & think I found a pretty good quote from Mark:

"The harness wires to the Hall Effect unit come out of a cover sleeve before they get to the dizzy side connector. Another single brown wire comes out of that same sleeve but doesn't go to the Hall. It is supposed to be attached to a bolt on the engine and has nothing to do with the Hall unit. It is a special ground wire for the ECU internal O2 sensor logic. It needs to have a good connection or the ECU internal O2 logic will be messed up. It is a brown wire, coming out of the same sleeve as the wires that go to the Hall unit."

(That other brown wire goes to the sensor for the oil pressure warning system that is down by the water pump.)
_________________
1986 2.1L Westy 2wd Auto Trans.

[Lufti]

Ok so I had an hour to fiddle with it and did some comparing between the single cab, my Westy and a buddy's '89 van. My Westy has the ground plugged into the spade on the side of the dizzy, the other 2 bolted to the head as pictured. Even though it was a clean connection on the SC I figured no harm in splicing the ground wire and trying the dizzy connection.

Currently replacing the blue coolant sensor connector, it was iffy. Think this could be the culprit!

I did swap the OEM coil for. Bosch Blue earlier during the component swap phase of diagnosis. That hasn't made a difference either.

If I can't solve it with a new sensor connector it's looking a lot like a full engine harness replace...yeesh. I hate saying it but OBD2 would be handy about now...lol sooo looking forward to testing the whole harness from end to end.

Thanks for the input guys, it's all gold!

[tencentlife]

[Lufti]

Hooray!

Folks after a long, long time of chasing this bugaboo it has been solved with a new(er) engine wiring harness. Stuff is 25 yrs old and its breaking up. Mine was extra special fun as it was faulty on an intermittent basis.
Once replaced it runs much better and I'm glad this one has been put to bed.
Thanks for the help, much appreciated as I was losing motivation.

[captdave]

Did you try a NEW O2 sensor? I had similar problems that were fixed with a new sensor.

[Lufti]

Captdave: no I did not try a new sensor, it would do the same thing with the O2 sensor disconnected so I moved on.
The wiring harness had an intermittent fail at the coolant sensor and then several more at the idle comp dbl relay.
After almost 30 years the outer casing was broken, wires chafed, terminals corroded etc. it was crappy enough to warrant replacement rather than repair and the replacement harness is working great.