Bitz problems

[mike.bike]

Can anybody help with my 911 bitzset. When i turn ignition, the first diode only flashes once? If i turn key 12-15 times for flash i can start the engine for 3-4 seconds?? Tony says i must have lost trigger from MSD to Megasqurt? I do not think Msd has anything to do with this. MSD is just for spark, and there is plenty! What do i do and look for?

[rwest]

Mike,

Although Megasquirt doesn’t control the MSD box, it does rely on it to get a tach signal to let it know your rpms. No signal and it doesn’t think the engine is turning over and it won’t send fuel.

Check your wiring from MSD to the mega to make sure it is still connected.

Rutager

[jpnovak]

I have a number of questions.

Did you install the EFI system?
Can you connect the ECU to the laptop?
Do you see an RPM signal in the laptop while the engine is cranking?

If you do not see an RPM signal on the tach gauge then you have a power issue or a tach input signal issue. Check for 12V input at Pin 28 on the 37 pin connector going into the ECU. Also check to make sure you have power on this pin while cranking (key-start position). If you do not have 12V input the ECU will not power up. Check the input fuses.

There are 3 LEDs on the end of the ECU. The one closest to the db9 connector is the ignition INPUT (Tach signal). It should blink once when the ECU is powered up. It will then, only blink while the engine is cranking and running because it is receiving a tach signal. Tony has used different tach input signals in his units. The early way is connected to the high side of the coil using a Schottky diode and current limiting resistor. The other way is to use the tacho output signal from an MSD or other ignition? Which one do you have?

If you are running a stock ignition the CDI should emit a high pitch whine. Have you checked with a timing light to make sure your ignition is working and there is spark going to the plugs? If the ignition is dead then so is the EFI because it relys on the trigger pulse going to the coil.

If you have an MSD (as described) you need to do the same test for spark. Most likely, the tach signal to the EFI and is split and will in parallel go to your tachometer. Does the tach in the dash needle move when you crank the car? If not, then the MSD could be dead and not giving a tach signal.

Do some checks and report back with more detailed info.

[mike.bike]

I am using MSD tac grey wire for tac, but can only read 3 volts when cranking.

[mike.bike]

Well have tried both pin 28 , it has constant 12 volt when turn on, but pin 37 is the grey for rev/tacho ? it has 5.6 volt when turn on, but when cranking it drops to 0.38 volt.?
rev gauge only moves one mm when i crack and stops. But if i turn on and off 10-12 times i can start for 3-4 seconds and rev gauge moves up?
The left diode flashe once only and stops when cranking, the middel diode is on . I have ordered a USB cable from USA Tony said i should buy so he could get a Datalog, i must say i know nothing about programing or PC , hope you can help me there. Tony wrote there is a free program from Studio that i must use , but know nothing about how to use this . Regards Michael --Denmark

[mike.bike]

Wow thanks for all support. Am waiting for usb cable to use on bitzbox, i am absaloutly no it specialst, hope you can help when i have the cable and program. With one do i downlod for useing the cable? Can anybody give a link to the right one. Best regards Michael-- Denmark

[timmy2]

https://www.bitzracing.com/docs/

[spuggy]

Originally Posted by mike.bike

pin 37 is the grey for rev/tacho ? it has 5.6 volt when turn on, but when cranking it drops to 0.38 volt.?

It's not DC electricity, so you can't read it with a voltmeter. it should be putting out a pulse - most of the later tachs are driven by a 12V square wave and you'll need an oscilloscope to read it.

Tachometer Compatibility Chart
HELP! tach died and I need to know what can replace it!
Tachometer pulses per Rev??
How to test the tach?

Pre-73 tachs are different.