82 Air Cooled Vanagon bucking issue

[joethebeekeeper01]

Hello All,

First time poster long time lurker.

I have a 1982 Air Cooled California Emissions Vanagon. I recently replaced all of my vacuum lines to cure a cold start problem. The van was running fine otherwise but had difficulty starting on cold mornings. After replacing the lines the van starts up with out any issues but now the van likes to buck under acceleration, the harder you accelerate the worse it is. You can simulate this with the van parked by quickly giving the van gas. I would put to old vacuum lines back on but they pretty much fell apart when I took them off.

Here is a link to a video of how it behaves while parked. van issues

First thing I did was check my grounds and cleaned them. I also cleaned the connections on the starter (now the starter turns over with more vigor) but Problem persisted.

I do have a Bentley and have done some basic tests:
Fuel pressure is ok
Testing the ECU through the wiring harness and everything was within specs
Tested the AFM and everything was within specs popped off the cover and the traces looked to be in good condition.

I replaced the plugs, wires, fuel filter and cap and rotor (I was going to anyway).

Yes, I have samba searched and these threads appeared to be the most relevant. I choose to believe that they all fixed the problem and went on to live a happy life but no one ever confirmed whether or not they fixed their problem. figure's crossed its not the ECU...

If you have found/know of a different thread that I have missed please point me to it.

https://www.thesamba.com/vw/forum/viewtopic.php?t=320166
https://www.thesamba.com/vw/forum/archive/index.php/o-t--t-636127--.html
https://www.thesamba.com/vw/forum/viewtopic.php?t=242032&view=previous


I'm hoping that someone can point me in the right direction so I don't waste too much time/money in the wrong places.

Thanks,

Joe

[djkeev]

Previous owner probably adjusted the engine to run with huge vacuum leaks.
(Unmetered Air) ..... You fixed them.....

Now it needs a good tuneup and adjustment with a known volume of metered air.

Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[joethebeekeeper01]

Thanks Dave,

I checked the timing and it was waaaay off. I re-set the timing to 5 atdc and the surging when parked (like in my video) stopped happening at 2500 rpm but moved at 35-3800 rpm when parked. This only happens when you move the throttle to 95% as fast as possible. If you slowly/reasonably quickly move the throttle it'll rev up pretty high and I didn't notice any surging. Is this something that is normal or is there some other adjustment or another component to check out that could make this go away? The good news is, I could not replicate bucking/surging/hesitation on the road which makes me very happy.

Thanks for the help!

[RCB]

From one 82 owner to another. Check the temp sensor and deceleration valve for proper operation. The temp sensor ( part number 0280130012 ) can cause all sorts of problems if its on its way out. If the deceleration valve ( part number 071133551A ) is wonky, it causes the idle to drastically increase and decrease and sometimes cut out.

[joethebeekeeper01]

The bucking came back (it probably never fully went away) a day later. I pulled the spark plugs to see what they were looking like and they were sooty black. I cleaned them and re-installed them and the van ran perfectly. Since then I replaced the plugs with a brand new set and now the van is good to go.

I assume the the timing issue I had after replacing the vacuum lines fouled my plugs.

Thanks again for all the help.

-Joe

[Wildthings]

Set your timing at 28° BTDC @ 3500+ rpm, with the hoses going to the distributor removed and plugged. This will give you the best possible timing, even if some of the components are no longer up to factory spec, which is very likely.

Does you engine have a two switch style throttle switch setup? If so and if the switch is badly out of adjustment or otherwise faulty that could be your problem. Pull the wires off of your throttle switch(s) and see what effect that has.