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1990 Westy lurching or missing
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clmb512
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Joined: September 21, 2004
Posts: 8

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PostPosted: Wed Sep 22, 2004 1:19 pm    Post subject: 1990 Westy lurching or missing Reply with quote

Hi Everyone,

I'm Chris, and this is my first post here at Samba. I recently bought a very low mileage, clean, clean, clean Westy. I've wanted one for a long time and I'm happy I finally got the one I wanted even though I paid a premium price for it.
Anyway, I drove it down to Yosemite this past week and it ran perfectly until we started driving home. On the way back it started to lurch a little almost like it was missing or something. It wasnt backfiring when it did this. At highway speeds it became quite pronounced and seemed to do it going uphill as well as down hill at almost all rpm ranges. Since it has such low mileage I figured it hadnt been operated very frequently and it may have some sludge in the fuel line or fuel filter as well as maybe a clogged fuel injector or two. I decided to stop and get some STP gas treatment and see if that helped. After stopping and pouring the stuff in the tank and restarting the problem immediately stopped. Obvisously this was too quick for the gas treatment to have any affect.
A VW mechanic recently told me that the MAF sensor (Mass Airflow Sensor) on these are prone to going out and that I should consider carrying a spare with me. Could this be the problem? Why would the problem stop after shutting down and then restarting?

Anyone have any ideas what may be causing this?

Thanks,

Chris
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[email protected]
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Joined: March 16, 2003
Posts: 165

jsdesign@thecia.net is offline 

PostPosted: Thu Sep 23, 2004 1:14 pm    Post subject: Reply with quote

You didn't say what year.
Without knowing that, replace the fuel filter. It could get shed some of it's dirt when it is shut off. The other possibility, has happened to several of mine, is the cat is breaking up inside. Large pieces of the honeycomb can block the opening to the muffler. When you turn off the engine, they drop away for a while.
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'65 standard bus
'87 Vanagon Westfalia
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clmb512
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Joined: September 21, 2004
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PostPosted: Thu Sep 23, 2004 1:52 pm    Post subject: Reply with quote

Its a 1990 Westy GL. I put that in the topic but didnt put it in the actual post, oops. Thanks for the suggestions. What is the "Cat"?
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Alan Brase
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Joined: March 28, 2004
Posts: 4532
Location: Cedar Falls, Iowa
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PostPosted: Fri Sep 24, 2004 8:15 am    Post subject: Reply with quote

This could be the so-called "Vanagone Syndrome".
When you shut off the ignition, it resets, so it starts working right again. It only happens under certaiin conditions and only to some cars. Not all need the fix for some reason.There is a $125 VW factory patch harness that goes between the harness and the AFM.
Go to the Vanagon.com list and search the archives for Vanagon syndrome.
Tons of stuff there, not all relevant, however.
I'd say most AFM's last 150k miles or so. (In this case, it's not a MAS, it measures volume, not mass- not as good as a MAS, but different.)
Also,it's possible that you've got some rust in the fuel tank from sitting around so long. there is no replaceable filter ahead of the fuel pump, but a screen in the pump itself. pinch off the inlet hose and take the hose loose and dump the contents onto a paper towel. You might have to ADD a filter ther if there is rust present.
Al
69 doublecab, Vanagons
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brandon043
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Joined: July 02, 2004
Posts: 6
Location: PA
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PostPosted: Fri Sep 24, 2004 8:57 am    Post subject: My Story Reply with quote

Had a similar problem with my '86 van - lurching or bucking to the point that it could not be driven. Most of my driving is in the city, and I was afraid to take it on the highway like that, so I'm not sure how it would have acted...maybe like yours, maybe not. Took care of the fuel system (new pump, regulator, filter, etc.) and it still did it. Checked all ground strap contacts, etc. Still did it. Verified the temperature sensor had the correct resistance. Turning off the key and restarting generally took care of it, and if I could drive through the hiccups, sometimes it would go away.

One day, however, it got so bad that it would not re-start, so in my frustration, I smacked the ECU panel mount under the rearmost seat. To my surprise, this had an effect and it did, indeed, start back up.

So, I bought a rebuilt ECU of the latest version (suffix D on the part number) from vanagain.com, installed it, and the problem has been eliminated.

The only thing not right now is a slight idle surge during warm up, which may be because the Idle Control Unit was not upgraded as well. I'm living with this, but am saving up for one. Fuel mileage is 19+ mpg in the city. Exhaust smells healthy and the O2 sensor is new. 190k miles, by the way.

Hope this testimony helps you. The problem may get progressively worse and eventually leave you stranded...like it did to me.

Incidentally, I also am theorizing that a ~53 mph rattle/buzzing suggests excitation of a natural frequency of the ECU mount, and may be the culprit. I'll be stiffening the mount either by coining/bending the mount or by welding on two 1/4 in steel rods in an X-shape so I don't have to spend the money on another ECU!
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clmb512
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Joined: September 21, 2004
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PostPosted: Fri Sep 24, 2004 6:50 pm    Post subject: Reply with quote

Thanks for the suggestions.

Sounds like I have a few things to try over the next couple of weeks. I guess I'll take it one at a time and see what solves the problem.
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wayoutjake
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Joined: September 19, 2004
Posts: 26
Location: Louisville, KY
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PostPosted: Sat Sep 25, 2004 2:35 am    Post subject: Reply with quote

Vanagon Intermittent Syndrome?

http://www.thesamba.com/vw/forum/viewtopic.php?t=84419&postdays=0&postorder=asc&start=500

I hate that.
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85 GL 2.1
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