Hesitation, horns, and points - oh my.

[obnoxiousblue]

Just came inside from installing a Pertronix on my 77 FI bus. Times it after, and took it for a nice drive (about 10 miles). The thing ran like a raped ape and felt great all through the gears - it even pulled a solid 60 up a good grade hill on the local highway.
Funny thing though, I went to honk my horn at some waving kids and then the bus hesitated - as in cut out - it instantly regained itself and again ran great - until I honked again that is when it cut out, again! It happens regularly and predictably, but at idle I can't seem to detect a change.
Any ideas?

**Update**
Was on the phone with our (much missed) Stuart. Who suggested I disconnect the horn, and see what happened - the problem went away! But the car started hesitating more. It's late here and I can't be out on my driveway honking the horn, so I suppose I'm in for the night. But if anyone has an idea what I might be looking for please chime in!
_________________
Mike
1964 Beetle
2001 Eurovan Camper

[Glenn]

Pertronix needs a good 12v+ power source.

I know the 6v units can miss when the voltage drops to 5.6v. I've had a number of Porsche 356 owners tell me they could drive at night with the wipers on.

Mike, you might want to add a relay, so the ignition key triggers the relay to provide a sold 12v source from the battery.

Or, just don't use the horn.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

[obnoxiousblue]

Why though would it cause issues now when the horn is disconnected?
_________________
Mike
1964 Beetle
2001 Eurovan Camper

[Wildthings]

[SGKent]

I am thinking the ignition switch is on its way out but some testing with a volt meter is warranted. That would be true whether points or electronic ignition. In fact you should not feel any difference between the two. Only long term as to not wearing out points.
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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

[vwwestyman]

For whatever its worth, my '73 does this too. It's motor features a later Bus fuel injection system and Pertronix ignition.

Just a small but noticeable drop from the engine briefly when honking the horn.

I don't know if I've tried it while idling or not.

I just attributed it to the fact that the horn takes a decent amount of current to operate and that is "stealing" the current from the motor briefly. Figure it is a slightly dirty ground or connection somewhere but it hasn't been bothersome enough for me to remember to check later.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[obnoxiousblue]

Replacing the ignition switch now. I called over to my FLAPS and ordered it at 8 am. They said it would be there by 1030. So I went outside and disassembled the bus and did a little chasing wit my volt meter. I disconnected the horn and found that the brown wire has good continuity from the switch chconnector down to the horn, the yellow and black wire has good continuity from the horn up to fuse S11 and the diagram says.
I'm hoping it is just as VWWestyman suggests - and if so will be going back to my points and condenser as I tried switching to Pertronix to ELIMINATE issues not create new ones.

Looks like Glenn was right - again.
Just once in 15 years I'd love to turn to him and say IM RIGHT! Lol

Will post back.

Some photos. Obviously at some time in the past someone cut the lock off. It's a clean break/cut so I'll see about getting it back on another time. It obviously hasn't caused any problems the past 10 years.

_________________
Mike
1964 Beetle
2001 Eurovan Camper

[Wildthings]

Still doesn't make any sense why pushing the horn button would do anything at all once the hot wire to the horn was removed.

Can't tell you what to look for

[TDCTDI]

I'd look for corrosion/voltage drops at the wire connectors before & after the ignition switch (Fuse panel (& headlight switch depending on model year.).).
The way that your switch is cracked usually only affects the start position or the ignition in the start position.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[Tcash]

If that does not work.
Note how the black wire that goes over to the coil N, supplies power to fuse S11 & S12.
To isolate which circuit the problem is in.
Pull S11 fuse and see if problem goes away.
If it goes away. Pop the fuse back in and start pulling the wires off the S11 fuse terminal one at a time until it goes away again.

If it does not go away on S11. Carry out the procedure on S12.

Good luck
Tcash

https://www.thesamba.com/vw/archives/info/wiring/baybus_77-78_key.jpg

[obnoxiousblue]

The new switch went in without a problem.
But it wasn't until I switched back to points that this funny hesitation went away. The bus is behaving totally normal now.
Could a Pertronix be THAT sensitive to voltage?
_________________
Mike
1964 Beetle
2001 Eurovan Camper

[SGKent]

If the ignition switch and checking for voltage drop doesn't get it there is one more evil gremlin that could be at work here. The coil issues a wave form that the ECU follows to tell the injectors when to fire. The horn would also issue a wave form when it is buzzing. That could overwhelm the wave form from the electronic ignition if it is weaker than a set of points, and mess with the ECU signal. So if it doesn't go away with the new ignition switch and testing voltages for corrosion, ask Telford to design you a trap that captures that horn wave as it leaves the horn. probably a choke and capacitor combination can remove it.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

I have had a bad diode in an alternator cause an electronic ignition unit to fire randomly, causing all kinds of spitting and backfiring.

[Tcash]

[SGKent]

TC - the battery acts as a huge capacitor. It alone may filter out any random wave forms that are interfering with the ECU. Also any corrosion along the path whether internal in the ignition switch, on fuses, or at connections can act as a diode which makes the situation worse (or better). Think about how the VDO tachs behave, jumping all over the place. Add a diode and it stops - in this case the diode stops half of the wave and somehow improves the signal - which can be filtering out reflected waves, or by cutting off 1/2 the wave form. Either way a diode changes things. Corrosion can act as a diode. The ECU is getting its signal from the waveform in the coil primary. Anything that alters that can have an effect on how the ECU delivers fuel. Without monitoring the waveform going to the ECU when the horn is hit I think it is going to be just trial and error looking for a fix. Dropping voltage certainly is suspect too and that is why I suggested the ignition switch. It would be the first place I would expect to see resistance build up.

Where is Telford? he should be in on this thread. He's an electronic engineer and incredibly understanding of bus circuits.
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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

[Tcash]

I am glad you said ECU.
To my knowledge Pertronix does not make a distributor that will work with Fuel injection.

"Please note: this distributor will not work with fuel injected engines."
http://www.jbugs.com/product/186504.html

There was a good thread on this, but I cannot find it.
https://www.thesamba.com/vw/forum/viewtopic.php?t=615938&view=next
http://www.shoptalkforums.com/viewtopic.php?t=146669

So unless Pertronix came out with a dist. designed to work with Fuel Injection, that is your problem.
Good luck
Tcash

[obnoxiousblue]

Tons of great info here. You guys are awesome.
I will say, after today's projects I took the bus out for a nice shake down, and with the points back in it is behaving normal again - I did clean the spades on the horn and replace one of the female connectors that go on the horn. Cleaned the contacts from the fuse to the switch, within the switch (and steering wheel ring) and back down to the horn and ground lines. The hesitation has gone away and the horn is louder and more "reactive" than ever.
I can't believe that my (preemptive) installation of Pertronix to eliminate issues created so many!
_________________
Mike
1964 Beetle
2001 Eurovan Camper

[Wildthings]

[SGKent]

[airschooled]

The Pertronix Ignitor I (oldest model) module works wonderfully with the L-Jet system. It drops right into the stock SVDA style FI distributors, though I have not tested it on a DVDA FI system. Allegedly, they're CARB compliment, so it doesn't void any emissions test, not that the refs would know…

The jumper test from the battery + to coil + would narrow down the list of suspects pretty quickly.

Robbie
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