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danno
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PostPosted: Mon Aug 13, 2007 7:32 am    Post subject: computer memory? Reply with quote

so does the computer in my 86 vanagon have a memory in it that it works off of and gets better (thats how it works in my 95 saturn I think) or is it all preset conditions that that determines how it runs.
just asking because after I discconected the battery to weld a cracked exhaust bracket it ran worse afterwards not a lot worse just the idle is a little week could this be related to the battery discconection or not a chance wrong tree?
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Volksaholic
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PostPosted: Mon Aug 13, 2007 8:43 am    Post subject: Reply with quote

I could be wrong, but I seriously doubt the Vanagon ECU is adaptive like many of the newer cars. I know the Eurovan transmission is supposed to have an adaptive controller.

There are two things I would check if I were in your shoes... if you haven't already. First is the oxygen sensor and its wiring. I only mention this since you said you were working on the exhaust brackets... I wonder if it got loosened up or the wiring got damaged. Second would be the electrical ground connections, especially the engine and trans to body connections. I'm assuming you were using an electric MIG or arc welder. If you clamped your ground somewhere on the body rather than on the engine/exhaust you will have been running your welding current through the engine and trans ground connections. That's not bad but if the connection were already getting questionable I can see how some arcing may have made it worse.
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danno
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PostPosted: Mon Aug 13, 2007 9:05 am    Post subject: Reply with quote

it was a mig welder and the ground was placed on the exhaust bracket close to where the welding was going on.
I was not sure about the adaptive computer just thought I would ask.

thanks for your reply
Dan
Comox bc

86 vanagon
95 Saturn SW2
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tencentlife
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PostPosted: Mon Aug 13, 2007 9:20 am    Post subject: Reply with quote

Yes, there is some volatile memory in the ECU, which is alluded to in Bentley in the section on checking the O2 sensor function. And I, too have experienced the same phenomenon as you have, that after disconnecting the battery the van seems to take some time to "relearn" how to run smoothly. It's bad enough that I go to great lengths not to disconnect the battery. I can't offer any credible explanation, though; it's one of those mysteries that's embedded in the ECU. The whole thing runs on memory since the datamaps are in ROM anyway, but this is something different. Some electronics geek could probably tell by looking at the chips on the board inside what type of memory it has, and perhaps speculate on how it works or why it has that.
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Dogpilot
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PostPosted: Mon Aug 13, 2007 9:29 am    Post subject: Reply with quote

It is actually obscure and little known, but the Digifant I needs to be reset after maintenance. Codes are generated on the 922-D version of the ECU.


"When resetting the ECU, the engine must be at normal operating temperature, all electrical accessories must be Off, the idle stabilization system must be okay, and the exhaust system must be leak-free.

With the engine off, disconnect the crankcase ventilation hose from the emission control valve atop the valve cover, then plug the hose. Start the engine and let it idle. Disconnect the blue coolant temperature sensor harness connector.
Let the engine idle for one minute, then reconnect the harness connector. CAUTION: DO NOT reconnect the coolant temperature sensor harness connects, while the radiator cooling fan is running.
Turn the engine off and reconnect the crankcase ventilation hose. Erase the OBD fault memory.
NOTE: Disconnecting the coolant temperature sensor with the engine running generates fault code 2312."
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danno
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PostPosted: Mon Aug 13, 2007 9:29 am    Post subject: Reply with quote

well if it thats the case i am just going to drive it for a while to see if it sorts itself out.

Thanks Dan
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brackish
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PostPosted: Mon Aug 13, 2007 4:43 pm    Post subject: . Reply with quote

Fascinating Dogpilot. One question about the procedure - "erase OBD fault memory" - Is this something that happens as a result of the process or something that one has to do? If it is a a step in the process, how does one do this?

Thanks
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Dogpilot
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PostPosted: Mon Aug 13, 2007 5:11 pm    Post subject: Reply with quote

Only the California late model Vanagons had the check engine light and the necessary switch to reset the codes. If you go to my public disk and download Digifant Test Tool.PDF you can add your own to any 86-91 Digifant with a 922-D equipped Digifant.

http://homepage.mac.com/WebObjects/FileSharing.woa...mp;lang=en

RETRIEVING CODES (DIGIFANT System)

Turn the ignition ON. Connect the black end of the jumper cable to the black diagnostic connector in center console under shift boot. Connect the white end of the jumper to the white diagnostic connector.
After five seconds the OBD CHECK light should begin to flash. Remove the jumper, but do not turn off the ignition. Record the flashes.
When code 4444 or 0000 appears, then either turn off the ignition or reinstall the jumper to end code readout.
Possible wiring faults should be checked and corrected before replacing a suspected component. Once the fault is corrected, the permanent fault memory should be erased as described below.

CLEARING CODES

Make sure the ignition is OFF. Connect the jumper cable as described in RETRIEVING CODES. Turn the ignition ON.
After 5 seconds remove the jumper cable. The OBD light should flash 4444. Turn the ignition Off or reinstall the jumper cable to end the procedure.
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brackish
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PostPosted: Mon Aug 13, 2007 5:44 pm    Post subject: . Reply with quote

Beautiful! Thanks.
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brackish
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PostPosted: Mon Aug 13, 2007 5:44 pm    Post subject: . Reply with quote

Beautiful! Thanks.
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Volksaholic
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PostPosted: Mon Aug 13, 2007 6:03 pm    Post subject: Reply with quote

Very good information... I stand corrected!
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Dogpilot
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PostPosted: Mon Aug 13, 2007 6:27 pm    Post subject: Reply with quote

It will also self correct after about 30 minutes to an hour. I originally found the info buried in service bulletins concerning drivability. It seemed the vans ran poorly after maintenance, so VW recommended the mechs drive it around for a half hour or reset the computer.

Don't feel bad about not knowing it. I found it totally by accident during one of my over-complicating a repair phases. It borders on almost worthless trivia, ergo why I remember it.
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98 Disco I
08 Range Rover SC
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bucko
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PostPosted: Mon Aug 13, 2007 7:20 pm    Post subject: Reply with quote

It's safe to assume that the 83.5 to 85 models do not have this "feature"?

I always read that there were basically two "maps"; an idle and off idle map for the earlier ECU's, and these maps were not able to "learn" unless a person was to buy a perfomance chip to replace these maps.

I think I saw a post here last year of a company that supposedly sells a so called performance chip (can't see how one could squeek any more out of a 1.9 liter).
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Volksaholic
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PostPosted: Mon Aug 13, 2007 7:42 pm    Post subject: Reply with quote

Dogpilot wrote:
Don't feel bad about not knowing it. I found it totally by accident during one of my over-complicating a repair phases. It borders on almost worthless trivia, ergo why I remember it.


I don't feel bad... other than potentially giving bad information. I'm surprised I didn't notice any of this behavior with my '88. I disconnected the battery when I dropped the tank to do the seals just before our Calilfornia trip and it seemed to run fine afterwards. Then in Oakland I disconnected the power so I could wire my inverter straight to the battery power (I was tired of the wire strung from the cigarette lighter). We then drove from Oakland to San Francisco and up the coast... I never noticed anything odd about the way the van was running. Maybe I was not being in touch with what the Vanagon was experiencing?
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Alan Brase
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PostPosted: Thu Aug 16, 2007 3:43 pm    Post subject: Reply with quote

Volksaholic wrote:
[Maybe I was not being in touch with what the Vanagon was experiencing?

Perhaps you need to get inta a higher level of consciousness.?
I'm half serious here. Ever read "Zen and the Art of Motorcycle Maintenance?"
It was a classic book from the 1970's.
People still refer to it. Especially on lists like this.
Al
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Alan Brase
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PostPosted: Thu Aug 16, 2007 3:47 pm    Post subject: Reply with quote

69doublecab wrote:
Volksaholic wrote:
[Maybe I was not being in touch with what the Vanagon was experiencing?

Perhaps you need to get inta a higher level of consciousness.?
I'm half serious here. Ever read "Zen and the Art of Motorcycle Maintenance?"
It was a classic book from the 1970's.
People still refer to it. Especially on lists like this.
Al

In fact, a quick search using key words Zen and Maintenance give 9 hits, including this one!
Al
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Al Brase
Projects: 67 sunroof bug, 67 Porsche 912 Targa, 70 Westy
Dec 1955 Single Cab pickup WANT 15" BUS RIMS dated 8/55, thru 12/55
To New owners: 1969 doublecab, 1971 Dormobile
Vanagons:
80 P27 Westy JUL 1979, 3rd oldest known US
83 1.6TD Vanagon, 87 Wolfie Westy daily driver, swap meet home
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