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You know, I used to do carbs back in the 60s and 70s, and I tried to polish up my Kadron skills enough to be happy, but the altitude changes on this island just didn't let me stick with it. EFI/spark is a superb alternative to carbs if you're forced into it. Otherwise it's more fiddling than most folks will want.

Until you're done fiddling, then the ECU just takes care of it. I'm sold, but then again I haven't started doing my install just yet.

And I think I've got a pretty good understanding of multiple carburetors. Singles are a piece of cake.

Polishing the polish: A while back I noted that EFI wants to know the injector dead time/ latency (time it takes to open the injector after the ECU sends the signal). In my case, the manufacturer had been purchased and the new owners couldn't find the information . PSIG (David) on the Speeduino forums posted a method for measuring the latency by varying number of pulses per cycle and logging/observing the automatic  corrections and pulse widths Speeduino came up with to fix the AFRs. I finally got around to  doing the measurements and calculations and can say that it works. The 17lb/hr Accels have a lag time of .6 ms.

On the slim chance that someone will want to give it a try, my interpretation of his formula was:

#a = maximum number of squirts per cycle (usually = # of cylinders)

PWa average pulse width when no AFR correction needed at max # of squirts

#b = minimum number of squirts per cycle (usually = 1 or 2)

PWb average pulse width when no AFR correction needed at minimum # of squirts

Here is a link to the draft paper from PSIG on how to run the test and do the calculation.

https://speeduino.com/forum/vi...mp;hilit=PSIG#p41357

Again, this is not absolutely necessary for Speedy to work well. It's only for those who show clinical signs of obsessive/compulsive behavior!

.

...0-5000 ft without a hitch...first outing up the volcano with barometric compensation...



Well Mike, that was easy enough.

When we go up to Tahoe (6000 ft, 7000 briefly over the passes on the way there), I do lose some power and idle drops about 200 rpm, but basically it runs OK.

If we're going to be up there a few days, I'll take a minute or two to tweak the 'mixture' screws, and set them back when we get home. All things considered, I'll probably keep doing that.

It's a nostalgic reminder of how life used to be in an analog world.

Besides, it's comforting to know that the car needs me.

.

I had to tweak(lean) my carbs down in the North Carolina mountains when we got there at a couple thousand feet ASL. The car ran like an absolute TOP down there.

I usually have to set them when it's really hot in July or so, then again in the fall once it cools and the air is more dense, even at home.

Just make sure the engine is good and hot when you do it.

@Sacto Mitch posted:

.



Well Mike, that was easy enough.

When we go up to Tahoe (6000 ft, 7000 briefly over the passes on the way there), I do lose some power and idle drops about 200 rpm, but basically it runs OK.

If we're going to be up there a few days, I'll take a minute or two to tweak the 'mixture' screws, and set them back when we get home. All things considered, I'll probably keep doing that.

It's a nostalgic reminder of how life used to be in an analog world.

Besides, it's comforting to know that the car needs me.

.

Yep, if it ain't broke, don't fix it. Unless you want to :-)

More polishing the Speeduino tune. Up to now, I've been getting my engine temperature from a VDO oil temp sensor. Speeduino uses the engine temperature sensor reading to calculate how much fuel should be added to the VE map when the engine is warming up. It's a pretty simple adjustment, but oil temp lags behind cylinder head temps by quite a bit especially on air cooled engines.

I decided to get a better sensor reading to drive the warm-up calculations. It doesn't need to be instantaneous, just a bit closer to actual cylinder head temps than the oil temp.

I decided to use the same head temperature sensor used in Type 4s and 914s - a Bosch style 0 280 130 012, also known as a VW temp sensor II (TSII). I found a cheap Chinese copy on eBay and got the calibration tables off the web.

Again, it just needs to track pretty close to the head temps, so I decided to make a mount to attach it to the head using one of the front exhaust studs.

I took 3/8" copper tubing and flattened about 4" length of it. I then folded the flat part in half and drilled a couple of holes. Once it was cleaned up, I cut the flat part off. I secured the sensor to the mount with a M10 - 1.5 nut. I then bolted the sensor mount under an exhaust nut.

PXL_20201113_034323607PXL_20201113_034325500PXL_20201113_034336312

You've got to put the sensor calibration info into the Tunerstudio temp calibration tool. I used a bias resistance of 2490 and temp data points of:

68F - 2510 ohms

140F - 593 ohms

320F - 45 ohms

I used the Tunerstudio warm-up wizard to adjust the warm-up table to match the new sensor. It definitely warmed up a lot faster than the oil temp. It ran up to around 250F and then dropped back to 180 when the oil cooler thermostat opened. I'll be tweaking the warm-up table over the next day or so.

PXL_20201113_040939536

Just FYI, this gives you a nice cold start. You can get an even better one by adding an idle air control valve. For that to happen, you need to add idle port connections to the manifolds. The extra idle air can't just be connected to the same vacuum lines used for the ECU MAP sensor. I found that if I set the idle between 1000-1200 RPM I really don't need it.

Things are really smooth now. I don't really have anything big on my EFI todo list anymore. If anyone has questions, post here or shoot me a PM.

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Very good info, Mike. I have 040 casting heads that have the threaded boss above #1(or#4) exhaust outlet so am using a GM 1/8" MPT sensor. The threads are close enough that it will work, and it's a closed hole so doesn't need to seal. It just needs to make contact and stay put.

I plan to also incorporate some extra ignition advance control into the warmup and idle control, hopefully that will work without an IAC.

Stick a fork in it. Marianne and I ventured up through the clouds to the summit of Haleakala this morning and the barometric corrections kept the car happy from 0 to 10,000 ft. Outside of getting bored and fiddling with it, I think this project is done. I've attached my Speeduino tuning file to this post for the future amusement of people who figure out how to do it better. All cautions apply, don't blow up your engine!PXL_20201113_201845210

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Stick a fork in it. Marianne and I ventured up through the clouds to the summit of Haleakala this morning and the barometric corrections kept the car happy from 0 to 10,000 ft. Outside of getting bored and fiddling with it, I think this project is done. I've attached my Speeduino tuning file to this post for the future amusement of people who figure out how to do it better. All cautions apply, don't blow up your engine!PXL_20201113_201845210

As they used to say, "Class dismissed!".

@Stan Galat, whenever you say that, I imagine someone kneeling down and getting tapped on the shoulder with a sword. Probably a Stanistan thing... Anyway, thank you!

Ape

"beloved by his people, who have no need for elections"



There's no need to be humble, Mike. You are a Hero of the Republic. The Dear Leader has decreed it.

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@Michael Pickett

Great thread, just finished reading the whole thing. At one point you mentioned this, but I didn't see any follow-up info on whether it actually happened, or the results if so.:

After doing more research, I'd have been better off configuring using the throttle position sensor (TPS or the Alpha-N algorithm) as the indicator of engine load. This seems to be the recommendation for ITBs anyway so I'll get that reconfigured soon and give it a try.

As I am partway through a similar build based on an MSII controller, this is of great interest to me. I believe MSII also offers a specific blended ITB/ITF mode for our use case scenario, not sure if Speeduino does the same?

Or, did you ultimately find simple MAP based Alpha-N adequate?

Hi James, Alpha-N (MAP) has worked fine for me so far, so I haven't changed it. Speeduino has added a blended load configuration, but I'm not sure if it's as mature as the MSII setup. If I were you, I'd go blended since everyone seems to recommend it for ITBs. I'm mucking around with idle air adjustments and still looking at solutions for picking too large ITB throttle openings. I rarely get over 30% throttle opening during normal driving. Good luck, the MSII is bulletproof!

Last edited by Michael Pickett

Ok, so I did just a little more fiddling with the idle air control and thought I'd add it to this thread in case anyone is foolhardy enough to take the same path. Idle air control is the fuel injection equivalent of a carburetor's choke.

It works by leaking extra air and fuel into the intake manifold at certain temperatures and for certain amounts of time after startup. It can also maintain a set idle speed. The particulars are set in setup tables. The mechanics involve a valve that can be controlled by the speeduino (or other ECU) and the setup tables.

I used the same Bosch 3 wire idle air control valve that I had used on my old Porsche turbo. In this case, it was a $28 Isumo equivalent I found on fleabay

https://www.ebay.com/itm/Idle-...&epid=1659374567

The connections are simple. One wire is connected to a fused +12v and the other two wires are selectively grounded by the Speeduino through the Idle 1 and Idle 2 connections. One opens the valve and the other closes it.

Screenshot_20210226-175913

I made a small capped manifold out of PVC pipe that connected to 1/4" NPT barbed fittings placed into the intake manifolds. The other end of the valve has a small air cleaner attached.

PXL_20210227_033415027PXL_20210227_033456177

I'm using PWM Closed + Open Loop as the idle control type. Each system is different, but if you go down this route and have questions let me know. I went this way not only to get a smooth startup, but to keep the air conditioning compressor from dragging the idle down at stops. Works great for both purposes.

Cheers!

Mike

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