Almost there...higher speed running.

[JPower6210]

Good morning folks-

I am working on my early 76 FI Westy and struggling to get performance where it should be. The bus is fairly new to me, and I have a visit scheduled with Colin at the end of September. I seem to be in a bit of an ACVW desert, haven't seen but one other bus and that was in a town 30 miles away.

Here is what I have-
Early 76 2.0 with fuel injection intact-
I bought the bus after it had been sitting for a long time- heads were replaced with HAM heads due to some valve issues.
I replaced:
fuel lines and filter and pressure regulator-
ignition system- Bus Depot SVDA with Pertronix, new plugs and wires.
TS 2
exhaust

The symptoms: starts and idles great although the idle might be a touch low. Starting out it sometimes stumbles, and at higher speeds I get what feels like a bit of a misfire/light bucking at 3/4 throttle. Sometimes applying full throttle resolves it. Bus is running around 375=380 with a DD gauge on #3. I get a lot of popping out of the exhaust.

I have timed it to 28ish with hose off and plugged, and it runs right around 8 with the hose back on. I say "ish" because the timing floats about 4 degrees at the high end and a couple of degrees at the low end. I have oiled the distributor wick. Fuel tank was clean, and it is all fresh gas. Mileage seems low, but hard to tell since I am not doing long runs with it until I get this sorted out. Injectors were cleaned and flow tested at Cruzin. Seals are all new, and I have smoke tested and resolved, I think, all the vacuum leaks, including running an all new line for the brake booster. FI system checks out for specs from the manual.

I feel like it is running a bit rich, based on the mileage and popping in the exhaust, but I am really hesitant to get into the afm until Colin is by my side. I'd rather have the correct DVDA distributor for the bus, but I have not been able to find one yet. And at least it is not the 009 that was there when I got the bus

Not sure where to go from here- the timing float bothers me- seems like it should be steady- Thanks all!

JP

[sgkent]

need to set the idle CO and see where the at RPM CO is.

[JPower6210]

I was afraid you would say that- I don't have access to a meter at this point. And, for some reason, I am really hesitant to get in that afm box- mine does not look like it has been opened up previously- But, I'll take a look at the LM2 meters and read up on the AFM-

Thoughts on the timing fluctuation?

[Bleyseng]

Worn out dizzy, advance weights are sticking due to old hard grease....Take the dizzy apart and clean it. Check for play in the shaft and have it rebushed to correct shaft slop. Install a Pertronix electronic ignition unit and store the points and condensor in your stash.

[tommu]

I believe this is running the Busdepot DVDA with pertronix? I have the same. Are you sure the magnetic ring is far enough down on the distributor? It's base should be level with the module base. My bus depot DVDA has sticky mechanical advance which I'm waiting to level out. I was getting a false idle timing reading.

Using a meter to view mixture is very helpful and wiring in an LM2 is straightforward. You can just take it through the engine hatch for diagnosis if you're concerned about running it up front. Do you have a bung on your CAT you can use?

I was the first to open my AFM too - and now I'm driving round with easy access to it for tuning. Follow Colin's advice for opening it, you don't need it to be out of the car. Then let us know what happens when you nudge the wiper a little. I'm running 9 clicks richer and this resolved cold start hesitation for me.

[tommu]

Ray's posts in this thread were very helpful for me when I had Pertronix issues:
https://www.thesamba.com/vw/forum/viewt ... highlight=

[JPower6210]

I believe this is running the Busdepot DVDA with pertronix? I have the same. Are you sure the magnetic ring is far enough down on the distributor? It's base should be level with the module base. My bus depot DVDA has sticky mechanical advance which I'm waiting to level out. I was getting a false idle timing reading.

Using a meter to view mixture is very helpful and wiring in an LM2 is straightforward. You can just take it through the engine hatch for diagnosis if you're concerned about running it up front. Do you have a bung on your CAT you can use?

I was the first to open my AFM too - and now I'm driving round with easy access to it for tuning. Follow Colin's advice for opening it, you don't need it to be out of the car. Then let us know what happens when you nudge the wiper a little. I'm running 9 clicks richer and this resolved cold start hesitation for me.

I am running the SVDA from Bus Depot- I am thinking it might be worthwhile to pull it and check the advance- clean up, etc. I'll check the magnetic ring, but I think it is down level.

I don't have a cat on my system, but probably have the ability to weld in a bung for the LM2 somewhere in the exhaust- could also use their tailpipe adapter.

[sgkent]

It is not uncommon for there to be worn traces in the AFM causing bucking. Likewise it is not uncommon for a prior owner to have tweaked the AFM trying to compensate for a vacuum leak. It is also not uncommon for worn plug wires and old distributor caps to track to an adjacent cylinder causing mis-fire and back fires. It is also not uncommon for the grounds under the plenum to need attention.

The fact the distributor advances to about 28 -29 BTDC then falls back to about 8 shows the advance is working. Make sure it does that smoothly four or five times to be sure it is not occasionally sticking. Stay out of the AFM, tweaking there only makes it worse. Check the PVC valve to be sure it is not perforated. Do that by applying a light vacuum to the small hole on top and see if it holds. Any airleaks in the case - missing dipstick, missing oil cap, loose valve cover combined with a leaky PVC can create enough unmetered air to cause issues. Last - were it me I would go back to points while troubleshooting everything. A goofy electronic ignition can cause all sorts of issues. So can corrosion where a spark plug wire plugs into a cap, or a bad plug wire or rotor.

[Amskeptic]

I am running the SVDA from Bus Depot-

You are close. Don't hyperventilate. Your mission is to check what you have for proper function. I have been running across a number of new SVDAs that have not been advancing correctly. The last one was hanging the timing at 16* for too long as the revs reached 2,500 rpm. Then it hung at 28* at 3,400 rpm, a correct spec, yeah sure, but then it kept advancing when I did the blip up to 4,000 rpm. That is a not-good thing.

By the way, timing scatter can be an indication of a crankshaft floating back and forth due to excessive end play. You'd be surprised. You can *see* the distributor rotor jerk back and forth when you move the fan pulley back and forth.

Generally, if you have a light hesitation at moderate throttle/rpms, you may have:
a) slightly inadequate timing for that rpm
b) slightly too lean (go crank on the AFM mixture screw clockwise a turn for your experiment)
c) aforementioned lousy spot on the AFM wiper
d) a hairline crack in the s-boot or some other overlooked vacuum leak
e) a leaky EEC valve on the air filter that has actually taken out your vacuum advance
f) an ignition breakdown, you'd be surprised at the global effects of one stupid spark plug connector being out of spec
g) the Universe is toying with your sorry ass
Colin

[sgkent]

g) the Universe is toying with your sorry ass

that happens to me all too often...

[JPower6210]

OK- so I pulled the Pertronix and went to points. After a bit of a false start with a set of Bosch points that were bad out of the box, I got the dizzy back in, with working points, timed it to 28 degrees before TDC with the vacuum hose off and it is running great! Then I go to the gas station and fill up- I make it back home, no problem. I take it for a short ride down the street and it dies on me turning back into the driveway, but starts back up. Then it won't start again a couple hours later. I check the points, and all seems well. I get it to start one time, and push the throttle a little in the engine compartment and it dies again. Won't start. Fuel pump runs when air flap is pushed with a chopstick, but I am thinking that I have a flow issue maybe. It didn't sputter and die, it just died. Maybe topping the tank up stirred stuff up and plugged the filter? I took the cap off and no whoosh of vacuum. I have a fuel pressure gauge but I can't it for a couple of days. Am I missing something easy?

JP

[sgkent]

spark
fuel and air
compression

Which one is missing?

Check for spark first. I am betting that the problem is somewhere in that area, maybe a bad ignition switch. You did put points lube on the lobes so the points rubbing block didn't break or wear down without it?

[Amskeptic]

spark
fuel and air
compression

Which one is missing?

Check for spark first. I am betting that the problem is somewhere in that area, maybe a bad ignition switch. You did put points lube on the lobes so the points rubbing block didn't break or wear down without it?

Global engine quit (no evidence of firing while cranking) is usually ignition-related, followed closely by an electrical interruption in fuel delivery system.

Go over prior work with open eyes.
Colin

[JPower6210]

Thanks all for the advice- I replaced the points again- the set I had in previously were used- no joy, but they tested ok with a light. I used a chopstick to move the afm flap to check for fuel pump- yep. While I was messing with putting the air filter back on I noticed that it looked like the afm plug might not be seated fully and worth a check. I checked the sockets to make sure none had receded and fully seated it.

Started up- I reset the timing and reset- and things are back to good. Now I need to get going on the wiper refresh and finding someone that can align the bus. I am going to continue trying to find the correct dizzy and try and get the pertronix to be functional, but right now things seem to be good. I am determined to stay out of the AFM until Colin is here at the end of September

[Amskeptic]

Thanks all for the advice- I replaced the points again- the set I had in previously were used- no joy, but they tested ok with a light. I used a chopstick to move the afm flap to check for fuel pump- yep. While I was messing with putting the air filter back on I noticed that it looked like the afm plug might not be seated fully and worth a check. I checked the sockets to make sure none had receded and fully seated it.

Started up- I reset the timing and reset- and things are back to good. Now I need to get going on the wiper refresh and finding someone that can align the bus. I am going to continue trying to find the correct dizzy and try and get the pertronix to be functional, but right now things seem to be good. I am determined to stay out of the AFM until Colin is here at the end of September

I'll be there if I get there . . .
Colin