Newer model ECU causing my engine troubles?

[d_walküre]

We took my 93 Weekender out to Colorado from Oklahoma a couple weeks ago and the engine gave out on us in the drive into Colorado Springs. Engine lost all power but still runs and idles, albeit pretty rough and backfires a little. It runs in what I would image "limp mode" would be. We ended up renting a truck and trailer and towing it back home... Not a cheap trip

In trying to diagnose the issue, I noticed the ECU has a date of 06/1997 on it.

It must have been swapped out a couple of owners ago because the PO left me meticulous receipts of work done in Boulder, CO. Are there any known issues with running this later model computer in a 1993?
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JesusV

1987 Vanagon GL Syncro SVX NAHT "Valkyrie"
1993 Eurovan Weekender "Camper van Beethoven"
1959 Bug

[ocelotpotpie]

Shouldn't be any issues - looks like the part number is the same.

If it was running fine before and now it's being funky, the potential ECU "mismatch" wouldn't be a concern if it were me.

[VAEV1993]

I think that 6/97 date would relate to this being a replacement ECU from about that time period. So while it seems it may not be the factory ECU, the part number itself is what you want.

023906022 for the '93 5 cyl, but the revision letter is what is important. This is an H. Is your van an auto or manual transmission?

As mentioned in the other reply above, it things were running normal before this event, then it would likely be the correct ECU, and the issue is something else...for example...our van needs the J revision and we once had an A ECU installed and it did not run well...and even backfired some.. It was pretty immediately evident though.

Perhaps it could just be that this ECU itself may have an issue...Were you able to check if there were any fault codes before you pulled it out? Of course it is also likely that there is some other cause...
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1993 Weekender - Hula
2002 Golf TDI
2017 Golf Alltrack

[d_walküre]

[d_walküre]

According to this article, http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/vw_blink.pdf my van should have a black white and blue test connector. I only see a black and white one:

I tried the testing protocol substituting my white connector with the blue one in the article. I can get the LED to light up with the ignition off, but it shuts off when the ignition is turned on.

Any ideas? Is there a blue connector hiding somewhere that I can't find? I can feel and hear either number 30 or 18 relay clicking when I turn on the ignition and then click off after a couple seconds when I turn the ignition off. And the van does turn on and runs.
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JesusV

1987 Vanagon GL Syncro SVX NAHT "Valkyrie"
1993 Eurovan Weekender "Camper van Beethoven"
1959 Bug

[Joshwa]

I’ve not seen a blue connector. Just the 2x2 black and white.

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93 Weekender TDI conversion (AHU)
93 MV TDI conversion (1Z)
Weekender rear cot
Late model cabin air filter on 93
Euro spec bumper install on 93

[d_walküre]

Thanks for the wiring diagram! It looks like I'm going to need it. After pulling down the fuse box, it looks like the yellow wire going to white OBD connector does not tie into the wiring harness anywhere. The gray wire does and gets a good 12V when connected to the black OBD connector.

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JesusV

1987 Vanagon GL Syncro SVX NAHT "Valkyrie"
1993 Eurovan Weekender "Camper van Beethoven"
1959 Bug

[Joshwa]

That's correct. The yellow wire doesn't connect to anything. At least on a 93 manual van. Just the 3 wires. Power(red), ground(brown) and k line /ecu (grey/white). Really, you can just pull the 3 wires and set them into an OBD2 female connector, to not have to use a 2x2 adapter.
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93 Weekender TDI conversion (AHU)
93 MV TDI conversion (1Z)
Weekender rear cot
Late model cabin air filter on 93
Euro spec bumper install on 93

[d_walküre]

[Joshwa]

I just read the linked file on the blink code operation. The white connector on the 2x2 is set up how the blue connector is described in the file.
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93 Weekender TDI conversion (AHU)
93 MV TDI conversion (1Z)
Weekender rear cot
Late model cabin air filter on 93
Euro spec bumper install on 93

[Joshwa]

[d_walküre]

Awesome! Thanks so much for the info. I'll try jumpering to an OBD2 scanner and see what kind of codes its putting out.
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JesusV

1987 Vanagon GL Syncro SVX NAHT "Valkyrie"
1993 Eurovan Weekender "Camper van Beethoven"
1959 Bug

[d_walküre]

Update: Got the Eurovan back running like normal... bad news is I don't really know how. I replaced the O2 Sensor, distributor cap/rotor, wires all at the same time and it runs great now! So, one of those was definitely the culprit.

Here's what most of the spark plugs looked like when the van was giving me trouble:

and some other parts I replaced...

Also, my Vag Com cable finally came in from China and I got VCDS working on my laptop:

Isn't this a beautiful thing?

Thanks for all the guidance and help from all the contributors to this forum. I could not have gotten this van back on the road by myself (not really by myself, but more self directed) without forum members' invaluable knowledge.

I was thinking of swapping this engine out with a diesel, but now that I got is back running better than ever, I think I'm gonna try and get it to 300K miles and above!
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JesusV

1987 Vanagon GL Syncro SVX NAHT "Valkyrie"
1993 Eurovan Weekender "Camper van Beethoven"
1959 Bug

[VAEV1993]

So great! Glad you got it back running right! Enjoy!
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1993 Weekender - Hula
2002 Golf TDI
2017 Golf Alltrack