no idle, no charging, new alt

[ironturtle]

So I replaced the alternator in a friend's 78 SB FI which wasn't charging.

So today I get the motor back in place and the car running, and now it has a poor idle, really lopey, occasional backfire noise if I'm not giving it gas to keep it idling, and guess what, it's only making 13.1 volts. Crap.

Car will run off idle, I drove it down the street briefly.

Not my car, has become my problem, anybody have any idea to start?
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1985 RWD Westfalia, brown with flowers, 2.1 transplant, 4 speed.

[14platoon]

Check wiring. My loom was melted causing two alternator failures. Loom runs along the left hand (mines left hand drive) of the car front to rear. Previous owner had out a huge fuse in due to a short, this caused the wiring loom to melt.
Just for info some of the wire loom looked good, if you followed it up the car this then revealed a bunch of bare wires where it had melted.

[ironturtle]

So if I unplug the wires to the AFM it idles. If I plug it back in it races, then almost dies and starts to idle super rough.
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1985 RWD Westfalia, brown with flowers, 2.1 transplant, 4 speed.

[volksworld]

unfortunately you've touched a lot of stuff in the process, and odds are most likely its something you touched...most likely a vacuum leak(crack in intake boot,hose not all the way in, vacuum hoses left off or locations swapped ,head temp sensor wire not connected or damaged(check it with an ohmmeter)...you could have made the situation worse if it was lean from a vacuum leak and backfired,bending or breaking the airbox flap...try to find the problem and dont go moving timing or idle speed around,it'll just make it harder to solve...unless you moved the distributor to pull the motor....sometimes you get an engine that has problems so some idiot sets the timing by ear to get it to run at all,then you try to set it correctly and cant figure what you did wrong...also check the electrical plugs on the F.I. components,the metal wire connectors can pull out of the plastic plug and arent touching even though they're plugged in(never yank on the wires)...most vw alternators dont put out a full 14 v,especially if the battery is fully charged...does the idiot light work(it must to energize the field,a dead bulb and it wont work...if it goes out and puts out 13 it could be fine.....p.s. you can change a fuelie alternator without pulling the engine

[ironturtle]

I didn't touch the timing and won't, I suspect air or vacuum leak as well.

Frustrating.
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1985 RWD Westfalia, brown with flowers, 2.1 transplant, 4 speed.

[ironturtle]

Found it. It was a larger vacuum hose that connects to this vacuum actuated valve (decel valve?) attached to the left side engine cover hinge. I had not connected it down by the main pulley.

As for the charging, is 13.6 volts enough?

Car idles great now. Thanks for the nudge.
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1985 RWD Westfalia, brown with flowers, 2.1 transplant, 4 speed.

[Blue69Baja]

13.6 is a little low if you are measuring it at the Alt.

If the battery was a bit low that may mean the Alt is working hard... Takes a while for the voltage to build up to 13.8-14.2 or so.

An additional check:

Turn on your headlights and measure at the Alt then turn the lights off and re-measure... Rpm 1500-2000 should do.

Check see if your meter is reading close. Maybe your meter is reading a bit low... .2 is all it needs to be off to mess you up. Compare with someone else's meter.

Another check, if the battery is charged is to disconnect the coil to distributor cap wire and try to start the car. Crank it for 10 seconds or so.. Reconnect the wire and start the car.. Measure the alt voltage.

Jim
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69 Baja with a 1914...
72 Super 100% orig...W/ factory air... 56,000mi
Even the spare is original..

[Blue69Baja]