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@Stan Galat posted:

I have a mico-squirt ECU from the last time, before I chickened out. Thoughts?

Should be bullet proof. Wasted spark and semi-sequential are minor limits compared to Speeduino or MS2. Doesn't support Bluetooth tuning out of the box, so that might either be a small pain or require some research.

On my Android phone, I use MSDroid tuning software. It's nearly the equivalent of Tunerstudio and a lot more portable. Bluetooth and MSDroid are just the thing for collecting a ton of data logging or to make that minor fueling or accel enrichment tweak without carrying a laptop and plugging serial cables.


Stan, you'll be fine, as Mike says, MS stuff is bulletproof, including the Microsquirt.

Mike, my Speeduino will have bluetooth for MS Droid, built-in idle stepper circuit(just in case) and built-in VR conditioner.

IAT and Temp sensors from CB, theirs are smaller diameter(1/8" pipe thread) than others I've seen. 

I'm finalizing my build list, currently attempting to figure out fuel pump/hoses and yes/no on surge tank. I've got to figure out exactly how much room I have, and where, and whether I'm using the external MSD pump I have or buying a nice new Bosch 044. The Bosch would sit inside the surge tank, a sweet little aluminum box. Low pressure in and out, and a return. High pressure comes off the end of the half-wet pump, the suction side sits in the well. Pretty cool, and not that expensive either.

Once I actually start ordering things, I'll start my own thread.

Speaking of individual throttle body (ITB) sizes, apropos hardly anyone. As I mentioned earlier, using my superpower to ignore important facts, I ordered 45mm ITBs for my 1776 that are probably 10-11mm too large, each. Based on my similar experience putting a Mustang 5.0 75mm throttle body on a supercharged Miata, I knew it would work, but I also knew that if I was way off, there would be drivability downsides. In the Miata case, this was easily solved because everybody and their 3rd cousin sell a progressive linkage wheel for the Mustang that makes most of the pedal travel control the very lowest portion of the throttle opening. As I discovered today, that is not the case for Weber ITF style crossbar linkage - huh, big surprise.

Now don't get me wrong, it's not terrible at all. In fact, the only time I notice it is when I'm driving over speed bumps and slight movements of my throttle foot creates noticeable jerking as the throttle cracks open and closed. I'll have to PERFECT this problem with a little home fabrication, but that's in the future. To prepare for this, I wanted some data about what part of the pedal curve was getting the most use.

I've been doing tons of data logging of every engine event over the last 2 weeks while tuning and playing around with settings. Megalogviewer (MLV) lets you load multiple datalogs at one time and just stitches them together into one big log. The only thing I was interested in was how much pedal (throttle position sensor - TPS) I was using during the majority of the time. Once I'd loaded several megabytes of detailed engine logging, I went to the Scatter Plots function and asked MLV to plot the throttle position against the engine load (MAP) and to just count the number of hits in each cell. The resulting scatter plot shows I spend at least 70% of driving time in the lower 35% of the pedal. So, that means I will need to try to fabricate a cam action that gives priority to the lower 35% of the TPS. I'm thinking of building an aluminum cam that lies on the face of the bar that the cable attaches to to reduce the travel of the bar during the first 35% of the pedal press. At least that's my current thinking... Change my mind or give me a link to someone who's already fixed it :-)

Here's the scatter plot:

Screen Shot 2020-08-11 at 5.44.58 PM


Images (1)
  • Screen Shot 2020-08-11 at 5.44.58 PM

I'm thinking in the case of a hexbar linkage, if the main throttle arm is rotated to almost opposite the pull location, you'd get some "cam" action. 

I'll try it on mine, even with carbs it should have some effect.

Mike, it is possible you're experiencing drivetrain "wrap". It could be just motor and trans mounts moving, causing the "pogo" routine.

I got rid of this in my Spyder by loosening the accelerator cable, leaving just a little slack in it, and resetting the full-throttle stop on the pedal.

On hex linkage, the length of the throttle actuator arm, and the position of the cable attachment on said arm, makes a YUGE! difference in throttle "feel".  I had to mess around with where the cable attached (in or out) to get to where it felt sorta-kinda right.  In the old days, Rochester carbs had several holes up and down the throttle actuator so you could choose aggressive to whimpy throttle action.  Webers and Dells are not so blessed.

Some pineapple farmer once said: "The only time I notice it is when I'm driving over speed bumps and slight movements of my throttle foot creates noticeable jerking as the throttle cracks open and closed."

Exactly what I get currently on my beloved Dells (which are forever known for holding EFI in contempt).  God help you if you change your mind just after initiating a launch and back off of it because you'll soon be on top of a bucking bronco, just trying to find a way off without breaking sumthin because your foot is pumping the gas pedal up and down.  Exciting, yes.  Cool-looking?  Absolutely not.

BTW:  You might have noticed that, if you hit said "speed bumps" at, say, 50mph or so, you don't get that jerking of the throttle business.  Just a little "tip o'the day" from Five Cent Racing, here in Swelter Cove of the Blackstone River (down to 91* at 4:30pm).

Last edited by Gordon Nichols

There are several pickup points on my "aftermarket" non-VW throttle pedal. I attached the cable at the closest one to the hinge point, which seems to work with the comparatively longer attachment at the throttle arm on the hexbar.

But what I'm telling Mike about, and you, Gordon, is rotating the throttle arm by one or two flats on the hexbar, but probably only one flat. This will give you a "cam" action, less movement initially around the "just open" part but as the throttle opens the arm will be more perpendicular to the hexbar. Then it will get to full quickly.

I believe a lot of pan cars are sensitive to throttle because they need a bow in the throttle cable housing, just like the clutch "Bowden tube" needs.

@DannyP posted:

But what I'm telling Mike about, and you, Gordon, is rotating the throttle arm by one or two flats on the hexbar, but probably only one flat. This will give you a "cam" action, less movement initially around the "just open" part but as the throttle opens the arm will be more perpendicular to the hexbar. Then it will get to full quickly.

What's funny is that as a novice with the crossbar linkage, what you are suggesting is the way I first installed it. Before testing and after seeing a better picture of a CBP setup, I took it apart and redid it. Guess I'm getting good at this...

Good move on ebay.

Stan, I've done that to replace some well-worn Cayman parts, the shift knob and the A/C controls. The ebay offer/counteroffer can be your friend, especially on outrageous buy-it-now prices that sit there for weeks.

I got automatic climate controls with brand-new buttons already installed for little more than the price of the new buttons alone, and upgraded from manual heat/AC. Plug and play as well, no coding needed.

I just replaced the el cheapo fuel pump with a Bosch 044. What a beast. It's easily twice the diameter of the old pump and makes about 1/3 of the noise.

To amuse my neighbors, I test drove it a block uphill before the 10 amp fuse that was totally adequate for the old pump said "No way, Jose!" I coasted back to my street and pushed it into the garage before it struck me what the problem was. Yep, the 044 is rated at 13 amps. A 20 amp fuse got me started again. Let this be a lesson to you all. Don't let Mike sign off on your test drives. 

Last edited by Michael Pickett
@DannyP posted:

I'm not on facebook, Mike. All I can see is the original post. I wonder if he's got his option jumpers configured properly? 

I'm doing wasted spark and batch-fire injection though, so I'll be using one VR crank sensor.

You'll be fine. It appears to be a pull up resistor problem with the VR conditioner board(s). Dana Hall just bent one of the plug legs to make his work. I'm running semi-sequential so it doesn't matter to me, either.

Last edited by Michael Pickett

Update and lessons learned: I'm having to redo my EFI fuel return.

The original design used a brass 3/8" tee between the fuel tank and the pump to connect to the fuel pressure regulator fuel return. This works, BUT, the pump is cooled by the fuel running through it, and the same fuel recirculates until the pump gets hot. Obviously, this is not good for the pump and hot fuel isn't as good as cool fuel for horsepower.

The usual EFI design is to dump the fuel return back into the fuel tank, being careful not to create bubbles near the gas feed at the bottom of the tank. 

I've got a 6an bulkhead fitting on order to return the fuel directly into the fuel tank. The larger amount of fuel being recirculated should lower the pump temperature.

 @DannyP, have you thought through where you are going to locate the fuel return back into your tank yet?

Last edited by Michael Pickett

When I changed a carbed Ducati over to FI the return line came in the bottom of the tank, but inside the return tube extended about 1/3 of the way up the tank and was aimed at the tank sidewall (return tube ended 1/4" from the side wall and was aimed at a 45* downward angle).  It was also at the other end of the tank from the fill cap.  The intake was, of course, well below that, but in the same general vicinity (maybe 4 inches way as the crow flies?).  No aeration issues arose, and there were no problems with extra vapors being created which might be an issue with our cars.

Yes. I'm going to attempt to install a 6AN bulkhead fitting on the gas gauge sender. It appears there might be enough room.

If it doesn't fit on the sender, I'll drill a hole next to the sender. I plan to heat and bend a special open-end wrench(Chinese throwaway) to slip in the hole and grab the fitting. I'll put the nut on the outside.

On the inside, I'm using a 6AN to 3/8" tube adapter. I bought some NiCopp fuel lines, they bend SO easy. I'll use about a foot, leaving a 90 at the bottom, directing the return fuel away from the feed port.

I'll be using 5/16" lines for feed and return, and 3/8" in the tank as an attempt to reduce the return flow speed a bit.

All my tube and thread adapters and such are coming from Jeg's. I'm buying hose and clamps from Amazon.

Here's what I did five-six years ago:

Drilled the hole so the fitting threaded itself in. The solder was just icing. A lil epoxy would've done as well. Never a hint of leakage.

Return fuel just pissed down in there until this spring, when I had some trouble with the fuel outlet being blocked by a gasket that fell in there. While chasing that I got the idea that aeration might be part of my problem, so I unscrewed the fitting and press-fit a piece of hard fuel line in the end, about six inches long, to carry the gas down to near the tank bottom. This did no harm, but was obviously unnecessary in retrospect.

Anyway, just saying. The fuel return is a low pressure system & doesn't have to be a big production.

Last edited by edsnova

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