Build update

Last update: 7/16/10

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Purpose of this page:

This page is probably titled incorrectly since the car is supposedly "finished".  But like most home car projects it will probably never really be finished. So this page will be devoted to what I'm working on right now.

1.  Updates are listed with latest one first.
2.  "MS" is my abbreviation for Microsquirt (the DIY fuel injector ECU)


7/16/10:  I've finished designing and programing a 16F876 PIC to use it as up-shift controller, gear display & MS interface. This small PCB will keep tabs on what gear the car is in, read the engine rpm, monitor a switch integrated with the paddle shifter and send a signal to the ECU to stop  injecting fuel until an up shift is completed. So far it and the MS are working OK on the bench. Now "all" I have to do is get the MS installed and working with this new circuit.

I really haven't made much progress on installing the ECU.  One pleasant reason is I got involved in a high school  solar race car this last school year. I had a lot of fun helping out with technical advice, pointing out that Ackermann IS necessary, doing the design of a new chassis in AutoCad to meet rule changes on an older solar race car, etc. etc.

This solar car has gone 80 MPH on solar power (and the on-board batteries) !  A great bunch of people and they learned a lot.

7/7/10:  As a test I temporarily connected the MS to the crank, cam and throttle sensors on the car. The signals do work driving both ECUs.  But I do have quite a bit of interference on the crank and cam signals which made the engine run erratically. I made up two Faraday shielded leads for the MS sensor leads and will try again if it ever cools off enough in the garage to work there.  I may have to go to a pair of op amp buffers to isolate the MS system from the sensors.

The grounding setup for the MS to the car is not ideal even though there are multiple ground connections on the the DB37 connector. Unfortunately the MS heat sink/ground system is also electrically connected to the case. If you electrically connect the case to any grounded metal of the car you immediately have a potential ground loop condition set up. For my first test, the case was not connected to the car ground system.  The Suzuki common ground has a separate thick wire that is NOT connected directly back to the battery. I will probably have to change that ground to connect to the point where the battery connects to the engine.

Since I am going to run the MS ECU in parallel with the Suzuki ECU I can still run the engine on the Suzuki ECU while checking the MS unit for proper operation. Once I'm satisfied with the MS connections I can then transfer the injectors over to the MS. This makes setting the MS up much easier than trying to get the engine to even start and then see what needs to be done to get all the parts to play nice with each other.

6/20/10:  I have done quite a bit of modification on the MS unit to energize a purge solenoid, energizing the radiator fan, building a 2nd VR (CMP) sensor input circuit, outputting a tach signal and assigning an input pin on the MS to cut the fuel delivery for my paddle shifter. There is an amazing amount of material that you have to read to figure out what the MS is capable of doing.  

1/8/10:  You can find my MS sequential  modification instructions here.   Be aware that I have NOT installed the Megasquirt on my car yet but all bench tests show that my sequential mod itself will work correctly. I'm a retired Electrical Engineer and I can tell you this project is not for the faint of heart!  But you will be a fuel injection expert when you get through with it.

12/18/09:  I've made lots of progress in understanding what the various circuits do and setting the ECU up for my engine. I bought 4 high impedance injectors from the junk yard to use in my bench tests. I'm quite surprised how much noise they make when being pulsed (especially at the equivalent of 18,000 RPM!).

The various manuals for the Extra3 firmware (sequential injection) advises you (in affect) to not use the original FETs to drive two of the four injectors my engine has. Instead they recommend using four (new) separate FETs to drive the injectors partially because of the way a modification is made to the ECU to allow sequential injection instead of bank injection. 

After studying the schematics (and redrawing them so all the parts are shown on one sheet I have come up with a way to use the original injector drive circuitry including the two original drive FETs. By removing some of the circuitry that isn't required when using sequential injection I have room on the internal heat sink to mount two additional FETs to drive the remaining two injectors.

11/25/09:  Since completing building the Microsquirt ECU I have been experimenting with the simulator to get familiar with what the various tuner menu selections do. I am working with firmware that allows the Megasquirt to energize the injectors in "sequential mode" as opposed to "bank mode".  Both methods have been used by manufacturers for years so it's not a case of one being completely "better" than the other. My GSXR engine uses sequential firing so I decided I would too.

Sequential mode means that each injector or ignition event is directed to the cylinder in order of the firing sequence (1, 2, 4, 3 in the case of my engine).  Sequential injection should give smoother low speed performance, slightly better fuel mileage and better emission control.

Bank mode has two drive circuits that fire 1/2 of the fuel injectors that your engine uses at a time in "bank" mode (i.e. 1 & 4, 2 & 3 or what ever combination you'd like, but always 1/2 the injectors at a time). If your engine only has two injectors then bank mode is perfect for you although it works OK with 4 injectors.

The firmware ms2extra was in alpha testing for quite some time with many people using it on a day to day basis. "Extra" firmware has all the features of the standard firmware and adds several features of it's own (such sequential, launch control etc).

The program author has been very helpful on the msextra forum with any questions etc.

You have to use the tuning  program "TunerStudio" for sequential mode since it is capable of utilizing the sequential injection features. A "release candidate" of "TunerStudio" is now available (for a nominal registration fee considering what the software can do) that will even tune your engine while you drive!

11/23/09: The original 12 Ahr motorcycle battery finally died. I bought a "Garden & Tractor" battery (350 CCA) as a replacement. The engine really spins over fast when starting now! I had to make a new battery box because the new battery is so much larger than the bike one. Details can be found here Battery-box.  Unfortunately garden batteries aren't build to a high quality and it failed after 90 days.

10/29/09: I'm starting to post articles about adding another ECU to control the engine fuel injectors. You can find the article links at the bottom of this page. At the present time I am building the Megasquirt -II ECU.

8/28/09: I've installed the oxygen bung onto my exhaust pipe for a wide band oxygen sensor. I am gathering other parts to use a DIY fuel injection ECU.

5/4/09: I am in the information gathering stage with the idea towards getting a MegaSquirt II ECU for the car. My plan is to use the original Suzuki ECU to control the spark (with a homebuilt gear indicator and an intelligent TRE mod) and use the MegaSquirt to control the fuel injection.  I will post articles on the whole saga once I complete the changes to (hopefully) get the AFR ratio under control.

2/15/09:  I recently refurbished my 1954 Sun fuel-air ratio meter and have done some initial tests/modifications to the fuel injection system. The engine -is- running extremely rich. Above 5,000 RPM the meter read 11.2 to 12.5 which is way too rich for any practical use at a steady speed. Below 5000 RPM the ratio is never better than 13.1 (still to rich).  My last gas mileage was 14 MPG before I made some small changes to the system.

Finished correcting suspension camber, bump steer, reduced my steering wheel lock to lock turns from 3 to 2 turns etc. I have posted articles explaining what I have done. You can access the articles here or through the "Links" located at the bottom of this page.

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