[T3] Bad day at the (FI) office

[Daniel Nohejl]

Usually, my wife, Jessica, posts here but I’m the co-owner of the 69 Type 3 with stock “B” FI that she has posted about in the recent past and I was the one who drove it around today and had a few experiences that make me want to install the pair of 32 PDSIT’s I have on the shelf, especially now that I can’t drive to work tomorrow!!!!

I’ll preface this rather long post with something that came up yesterday when Sean (who also posts to this list) came by. In specific, he noted two things about our motor: one was a lack of power with the pedal floored and the other was a hissing sound like an air leak in the engine bay. 

As to the pedal, I feel like I’ve always kind of had to finagle it to get harder acceleration. Generally, if I just floor it, nothing really happens as I discovered to my dismay a few months ago when trying to pass someone on a country road. I actually had to fall back behind the car I was trying to pass because I couldn’t really accelerate. But this was with another motor with mostly entirely different FI components. In other words I always kind of worked around what I thought was a quirk of the FI system. I sort of slowly work towards full throttle and when it feels right, I go for it and usually it works fine…..sometimes it seems like it takes a little while for the motor to catch up with the throttle position if that makes any sense and sometimes it’s all fine.  Anyway, today, the motor seemed a bit underpowered and it was difficult to get the extra acceleration I wanted at times.  Overall, the car was still quite drivable, just not as peppy as it has been of late. 

Also, while driving home from work today, I got random hiccups/bucking….sometimes while accelerating, sometimes when decelerating. When I finally got off the highway, the idle dipped way low and the motor almost stalled. It did that a few times but then recovered though it happened a few more times at a few stop lights.

Then, I stopped for an errand and afterwards the car wouldn’t start. After some poking around I realized that  the hose from the AAR to the IAD had been leaning on the “porcupine” ground cluster and it had broken one of the grounds. Not the injector grounds, but the other one.  I say “other one” because I’m not really sure what else grounds there. According to the wiring diagram in Bentley, there should be two wires in that single connector just like the injector grounds. Those should be wires 11 and 31. I only have one wire and the number collar that Joe put on it when he made the harness has vanished. In my head, that’s the ground for either the TVS or the pressure switch. But those being disconnected wouldn’t cause the car not to start so maybe someone can enlighten me as to what ground that is? If it matters, it’s what would be the only wire grounded at the case in a 68-69 system. Here’s a link to a pic of the wire, now with a new red connector because that’s all I had and with the hose moved out of the way. 

http://www.thesamba.com/vw/forum/album_page.php?pic_id=1477735 <http://www.thesamba.com/vw/forum/album_page.php?pic_id=1477735>

Once I fixed the connector the car started up fine. Of course, I thought that wire had been the cause of my bucking and hiccuping but I was wrong. 

So now on to the hiss!!! You can clearly hear it here, in the vicinity of the IAD:

https://www.youtube.com/watch?v=AGZ3KKKfyNU&feature=youtu.be <https://www.youtube.com/watch?v=AGZ3KKKfyNU&feature=youtu.be>

But if there’s a vac leak, why does it idle so smoothly except for once or twice every minute or so?

When I listen around with a length of hose to my ear, the only place I specifically hear hissing is around the elbow/boot from the IAD to the oil bath. There’s nothing down by the AAR to IAD hose, nor near where the MPS and pressure switch vac lines join the IAD. No sounds down by the injectors, nor where the runners meet the head where we have the correct bakelite spacers. I can’t really pin it down and spraying with carb cleaner didn’t reveal anything. In my experience, if there’s a vac leak at idle, it produces a regular pulsing effect where the idle goes from normal, then dips, then goes back to normal, etc. In our current situation, the idle will be fine for minutes at a time but then will hiccup (go rich on the AFR meter and dip) and recover to normal.

Now, at idle, the hiccuping is worse if the headlights are on, but weirdly there’s no major voltage drop when the hiccup happens. Here’s a video. A few seconds in I say “hmmmm” and that’s when the motor almost cuts out. You’ll see that the AFR goes rich but nothing crazy happens with the voltage. If there’s actually a vac leak, then why is the idle stable for long periods of time followed by one or two hiccups? The more I kept the motor running, the more frequent these hiccups became at idle but they were never as rhythmic or predictable as the “hunt” one gets at idle when there’s a definitive vac leak

https://www.youtube.com/watch?v=lse2TyHcNkA <https://www.youtube.com/watch?v=lse2TyHcNkA>

We’re really not sure what to do now other than reseal all known vac leak points even if there doesn’t seem to be any issue.


Sorry for the length!!!


Daniel



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