Differences in ECU between the years?

[1977_L63H_P27]

[SGKent]

then lean it a turn on the screw by opening (counter-clockwise) and see if the RPM increases. If it does then that is why it idles slow.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[1977_L63H_P27]

[SGKent]

I tried to find a diagram for the 1977 vacuum lines on an automatic and could not come up with one. I found one for a 1976 but some parts changed in 1977. On the 1976 diagram, the plenum has two nipples. One goes to the decel and fuel pressure regulator and the one on the oppisite side goes to the vacuum modulator.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[1977_L63H_P27]

Thanks for all the help volks, but I'm fed up. I'm now in the market for some good dual carburetors.

Went out there this morning, hit the key and she started right up and purred along. I leaned the mix out one turn and the exhaust smelled better. Then, after she warmed up, decided to take her around the block. Seemed to be a little on the weak side, but smooth off of idle and drove pretty well. When I got home, I stopped and put her in reverse to back into her parking spot and she died...

Now it's back to starting and dying within a few seconds. If anyone needs fuel injection parts, including four rebuilt injectors from Fuel Injection Corp., give me a shout
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[Wildthings]

Have you done your diagnostic checks through the wiring harness from the plug on the ECU? This should catch any problems in the harness and the connections between the harness and the senders. Check carefully that all the pins are correctly installed in any and all of the plugs. If they have backed out especially from the ECU plug that will cause hard to find mystery problems.

[1977_L63H_P27]

[germansupplyscott]

[SGKent]

[vw76westy]

what happened to this comment you made

[1977_L63H_P27]

[SGKent]

that is too bad. We had to rebuild our 1977 FI and getting it perfect is a pain. So is tuning a carb for that fact, especiially if your state or Federal smog laws change to be more conservative, which is pretty likely given the lobbists pushing for getting old cars off the highways. If the frustration wears off and you decide to work on the FI again, let me know and I will help you work thru it.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[SGKent]

[1977_L63H_P27]

[rainierdeklark]

The FI system is fantastic. You just have to measure every component, which is possible with a regular multimeter. Check if the vacuum-can on the distributor is not leaking and if every vacuum hose i tight. Then check if the CO level is around 2% (without catalic converter). If it's slightly off, you can adjust it with the screw on the AFM, otherwise you have to move the arm in the AFM a bit.
I'd rather drive with the FI system than with old and most likely worn dual carbs. Those are nearly impossible to adjust to complete satisfaction.
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Modern cars are nothing but visual pollution !
www.klarkclassiccars.se

[1977_L63H_P27]

Okay..so I took a breather. Left it alone for a few weeks. Then I came back here and started reading. Steve (SGKent), you ended up helping more than you know. I found a couple of places where you'd posted a link to this
http://www.thesamba.com/vw/archives/manuals/afc_fi_training_troubleshooting_manual.php
trouble shooting manual.

I started early today by taking most of the plumbing back apart. Then started testing each piece in order. I even made a makeshift fuel pressure guage from a cheap tire gauge. It worked great! After testing each piece, and getting good readings, I started connecting the plumbing. I guess when it backfired it knocked something off that I just couldn't see before, because after it was back together it ran perfectly. I've only driven her about 8 miles but she really is running great.

I still have a low idle, but I can deal with that . Thanks for all the help volks, and if you're considering FI, DO IT!
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[SGKent]

I am very glad to hear that. Here is why - one it is a load off your mind and you can enjoy the bus now, but more so, adding dual carbs doesn't lower the frustration, in fact the set up was likely to be more of a pain than finding the FI problem was.

If you enjoy reading, get a book from Amazon called Bosch Fuel Injection & Engine Management by Charles O. Probst, SAE. It covers so much more of the design and how it works. I am one of those people who have to be able to build it in my head to work on it and his book really helped me understand how FI works. I am no longer intimidated by the L-jetronic system because of his book.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[SGKent]

btw - you can slightly open the screw on the throttle body and it should speed up your idle. Check your timing too.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[1977_L63H_P27]

[SGKent]