1979 carburetor to fuel injection conversion

[Clatter]

Sometimes, if some really rich carbs have been at work the ring sealing can become marginal from fuel wash.
Also the soot from that can start burning off as the tune gets leaner/cleaner/hotter.
So maybe some hard run-time with a better tune will clean it up all by itself as the rings come in?


Did you put your compression gauge on it before the switchover?
Would be cool to see the numbers..


Was going to guess ballast resistor on the startup issue,
But then remembered we have a '79 CA here..

You forgot to put the rockers in on that one head!
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Bus Motor Build

What’s That Noise?!?

[airschooled]

Clatter, a progressive with no preheat, FI plastic manifold spacers, and ten years of short trips to the beach? What could possibly be getting past the rings?? Here were the plugs from 3/4:

Compression was 120psi on #2, and 105psi-ish on the others. I'm assuming the lifters weren't 100% inflated when I did the test two weeks after it got here… It drove itself off a tow truck with a surprisingly smooth and quiet cold idle, and after a lap around the block, a spark plug drop test showed nearly identical performance across the board. No visual smoke, and the oil cap didn't dance too much when left loose at idle. If those signs look good, I can get the car to pass CA smog barring any architectural issues like a performance cam, sinking valve, or secretly blocked-off EGR.

Planet Earth do not have a working PCV valve in our budget, so I'll be making another classic "raygreenwood PCV metering orifice." This has worked well to drop hydrocarbons for me in the past, without creating oil leaks. I have 3D printed 2, 4, 6, and 8 millimeter holes in various short 22mm cylinders for insertion into the PCV hose. Once we find the 'best' size, I'll turn one out of something that doesn't melt.

--

Interesting, newest test shows wildly different results in 15mph vs. 25mph tests. The manuals run the engine at an identical RPM in 2nd/3rd gears. The auto does not shift, but stays in 2nd gear and increases speed about 400 RPM.

Any insight to these readings? The new exhaust will be here next week and I can use my O2 meter on the pre-cat bung. For now, I'm just going off of AFM poking and prodding responses.

Again, the car is used for mostly around town trips and beach cruising; it will be fine to run a smog tune year-round. What are the best numbers for catalytic converter life?

--

In other news, the "Motor" manual that EVERY shop around here swears by has a '79 CA as needing a Cat and EGR. See for yourself…

So how can we educate the state about this likely error? Only the Motor manual makes this error; the Mitchell guide is ironically correct. The '79 CA plenum doesn't even have a point to mount the EGR valve. (Unfortunately, I don't have a '79 plenum. )

More tuning will wait until I get the gas cap keys in the mail… Then it will be a full tank of premium, to keep the NOx down, of course.

Robbie
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[pittwagen]

This question is for Clatter:

[SGKent]

lean misfire maybe on the HC, or some kind of misfire, old fuel

The one thing on the plugs that caught my eye is the carbon trail up the plug and how wet the threads are. Were they loose in the heads?
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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

[Clatter]

[pittwagen]

Thanks for that. I wonder if the signal would be compromised if I literally unplugged the O2 connection and plugged the 2 wires into a relay triggered by a switch on the dash.

I have removed all the left side CA only exhaust and tin and replaced it with the 79 federal parts. I have an Empi header with a Hedman collector (same bolt pattern as the Empi flange) that has an O2 bung (where the O2 sensor now resides) and a 2.25" turbo and tailpipe. Exhaust flow is improved in the collector area. There is a noticeable increase in mid range power. Too bad that was not an option for you CA folks.

I was going to remove all the CA FI parts topside. It just runs very well and I don't really want to mess with that. Being able to turn off the O2 sensor on the long.hills would be perfect. No smog.checks here in BC anymore.

[SGKent]

an engine makes more power at 14.7:1 because more heat is generated however the 2L air cooled engine can't shed that heat and it causes other engine problems. The square flanges help pull heat off the heads.

That said, I was reminded this week by a very good friend whose father was a mentor of mine, and who helped develop the Super Vee T4 engines in the 1970's ~ heat in a T4 engine doesn't come under control until the heads and pistons tops are ceramic heat coated. As a community we need to start making that recommendation when people have the time to do 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

[airschooled]

Steve, that may be true on a race car, but VW built well over 100,000 two-liter Type 4 buses…
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[airschooled]

Update: My LM1 took a spill on a job last week and calibrated itself for a natural gas conversion. So when I saw 15:1 AFR, I richened up the mixture a tad. Failed via hydrocarbons. Coincidence?? 17:1 natural gas is about 15:1 gasoline, so the engine was actually running around 13:1 for the test!

Can you say hello NOx??

Robbie
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[SGKent]

[airschooled]

It's been a hot minute, but I can say…

After waiting for exhaust parts from all over the world, of course only the new muffler shows up leaky and crooked. At least it was dented, so I could exchange it without fuss… The new one just had weld slag all over the flanges; at least I could file that away.

Now with four years of dragging air-cooled cars to smog shops around the state, I can safely say I think MS Smog in Vista CA is by far the best to work with. So many shops have taken money running pretest after pretest, only to get blindsided with unexpected results from one tiny change. Moises and his family ran the sniffer in "manual" mode for HOURS for me, while I chased intermittent issues, fiddled with settings inside the state's narrow range of acceptable parameters, and ended with a car that was drivable but not powerful. Kinda jittery after refueling. Just like when they were new.

You may notice the '78 California exhaust setup…As long as the cat EO# matches what the smog station has listed, no shop has ever cared about various piping arrangements to achieve the cat installation. I highly recommend this path to CA '79 owners who are looking for less expensive and time consuming stock exhaust options. (Hydrocarbons were cut 40x, and that's with a RICHER mixture for NOx reduction!)

This was with a formerly-unmolested AFM, which originally spiked NOx well over 2,000 PPM. The end result was achieved with six clicks richer on the cog wheel, and limiting the distributor's advance to the low end of spec, while running the timing 2-3° retarded from spec. (Any lower would have been a fail.)

Clatter, I think you had something going, talking about waking the engine up… After 20 miles floored on the freeway yesterday it just FELT better. Smoother idle, less stink, etc. This is with 2-month old premium fuel…

I think we could have lowered the NOx without doing all the spark advance work, but it would have wasted the cat with hydrocarbons in no time. The six clicks were mandatory; the car was lean-misfiring and driving up the HC and CO beforehand. The AFM that came with the donor FI system still drives the best, but it's been HEAVILY messed with by the tool markings, so I didn't bother with that after gross-polluting our first two pretests.

Anyway, I'm glad to be done with this, and the owner is stoked to be legal again.

Of course, the TS2 crapped out in my driveway.
Robbie
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[SamboSamba22]

Great information Robbie.


Sam
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The Bus Barn Ltd. Co.

Oct. ’67 Double Cab (’68 Crew Cab)
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March '69 Delivery (Panel Bus)
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[THall]

[airschooled]

[telford dorr]

One note to people running a cat: DON'T run with the O2 sensor unplugged, unless you don't mind cooking the cat. It won't appreciate all of the extra hydrocarbons. (Of course, if you've been running carbs, the cat is most likely already toast...)
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[SGKent]

Robbie - there is a thread somewhere here where I measured the spring tension on a NOS AFM. Set that spare AFM to that tension, and then use the slider to get the mixture you want at that spring tension. Then fine tune with the spring. I have set several AFMs that were tampered with, and each time setting them up this way was easy. In one case just setting the spring tension up to the factory tension, the AFM tested perfect. The slider had not been touched.
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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

[Bugster78]

Hopefully this thread is still alive…quick question on FI gas tank…I know the “official version” has two connections on the bottom…one for supply to fuel pump one for return from pressure regulator….BUT, would it be possible to just put a “T” connection on a carbeurator tank to serve the same purpose and save $400??

[SamboSamba22]

[telford dorr]

You really need to use a FI fuel tank. It has a little short metal cylinder in it which can hold fuel. The return fuel is shot into the bottom side of this cylinder using a venturi action to also drags in tank fuel. This causes the cylinder to fill up and overflow. The FI pump gets its fuel supply from the bottom of this cylinder. The result is that, even with a low fuel tank level, the cylinder keeps an air-free stream of fuel going to the pump. It also holds enough fuel so that hard cornering with a low fuel level doesn't cause fuel starvation.

A "T" wouldn't provide this service. I have FI on my '71 bus, and anytime the fuel falls below 1/8 tank (indicated), you need to take it easy on corners (like on-ramps). I generally keep the tank 1/2 full or better, so not an issue. Note: I return the fuel to a tube brazed onto the filler neck tube (not ideal).
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[SGKent]

we have a plethora of threads where people have used a tee. The problems they encounter include cavitation, and boiling of the fuel in the line when it passes thru the line over and over. The FI tank acts as a huge heat sink for the heat the fuel picks up traveling thru the line, and therefore it delivers cool fuel to the pump. The FI tank "cylinder" that Telford refers to are a set of baffles shaped like a box down inside the tank.
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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