Matt Cramer

You should have the trigger wheel set to zero when you aren't using a wheel decoder. I've seen quite a few cases where it was left on by mistake, and this will give you a zero RPM reading.

There's a couple things to check here. First, if you've got a Stimulator, I recommend testing the Megasquirt out on it and letting us know the results. Second, are you using the wheel decoder?

You might want to try reinstalling MegaTune, as this problem sounds like it's with the PC rather than the Megasquirt. Also make sure you don't have anything that could be causing the adapter to wiggle - this often makes MegaTune do strange things.

Is that our external USB adapter or the internal DLP-TXRX circuit board?

For MS-II, you calibrate the sensor in MegaTune. Go to Tools -> Calibrate Thermistor Tables. You'll find the default settings for a GM sensor on the MegaManual sensors page if you scroll down a little ways. It's possible that your sensor may have an unusually low resistance - you can check it manually if the default settings don't fix it.

The circuit for the extra outputs isn't in the main V3 schematic - what you do is add a transistor driven by the processor. The MSnS-E manual has the schematics for how to add this circuit here: http://www.msextra.com/manuals/MS_Extra_Hardware_Manual.htm#outputs

You shouldn't need a pull-up resistor. I am not sure if adding one will help.

I don't see anything wrong with the MegaTune version. What code are you using?

The trouble with a multimeter is that while the signal will bounce up to 12 volts, it may not stay there long enough for your multimeter to capture it. This does look a little bit low, however.

So what is the problem - do you need a fuel map, or is there another problem?

The important thing is to get the tach signal going. Megasquirt won't inject any fuel until it gets the tach signal. The EDIS box will spark on its own if it is working correctly, with no input from Megasquirt. Check to be sure you have the PIP signal coming in on pin 24, and make sure there is a signal on that line. Check the PIP line with a LED tester; the LED should blink when you crank it.

It controls the spark timing in a manner very similar to the stock ECU on many fuel injected cars. In its standard distributor mode, Megasquirt starts by reading a signal from a distributor pick-up that always happens at the same number of degrees before the next cylinder to fire reaches TDC. It calculates the spark timing based on manifold pressure and engine RPM. If this trigger occurrs 50 degrees or more before TDC, Megasquirt will start counting down a time-based delay and then trigger the ignition through either a built-in VB921 power transistor or an external module like an MSD box. If the trigger angle is 20 degrees or less, it will work in "next cylinder" mode, where Megasquirt will predict when the next pulse will arrive. The output is about the same. See here for a very detailed description about how the timing calculations work: http://www.msextra.com/manuals/MS_Extra_Software_Manual.htm#this_next The distributor cap does have a fair amount of provision for timing advance and retard - the stock ignition control changes things by tens of degrees, after all.

Yes, we've got some pictures of the circuit on a V3.0 board on our website.

The Microsquirt is MS-II based; the eMS Pro is actually closer to a MS-I. Unlike a normal assembled MS-I, however, it has almost every option on the MSnS-E option list installed. The eMS Pro is aimed at a crowd that's do it yourself enough to want to install an ECU, but the sort who draw the line at wanting to build or customize it on their own.

Yep, two banks of three. You can either have one controlling the front three and the other controlling the back three (that's how I have my Dodge Dart set up) or have one driver controlling the odd numbers and one controlling the evens. I've heard the odd-even order is often best, but there's some controversy over which one is the optimal setup. I suspect different combinations work better on different engines.

Stranger things have happened. I've seen a few people use Megasquirt for ignition control with carbed engines. Usually it's because they put a set of Webers on an engine with no provisions for a distributor, or so they'd only have to deal with one issue at a time when installing it.

Yes. I believe the HI-6 is a capacitive discharge box, and you should not trigger Megasquirt off the negative terminal of the coil when using one of those. A capacitive discharge ignition runs at several hundred volts, too much for either Megasquirt or most tachometers. Use the tach output wire.

First, check to be sure they're grounded to the same point. A ground offset can make a wideband read a little bit higher or lower than it should.

Yes. The V2.2 board has a Zener diode that protects it against many high voltage spikes, a capacitor for a little bit of noise filtering, and a diode to protect it from reverse polarity. The V3.0 board adds a metal oxide varistor for more protection.

You can use one of the IAC jumpers on a V3.0 board (on a V2.2, it's X11 through X14 instead). The IAC wires are in a normal relay cable, but not used for idle control on a 280ZX.

I have used a car stereo filter on my Dodge Dart, which has an incredibly noisy electrical system. While the noise doesn't seem to do any physical damage, the filter cut down on resets very well. One more tip - route the signal wires leading to the Megasquirt away from high voltage ignition wires. Having these lines touch the ignition wires can cause resets or issues with the firmware, even if they are still insulated.

I've heard of a few people using the divider chips but haven't tried it myself. Not sure how it affects the accuracy.

Terminal 11 is for spark control. Having it connected to the coil is going to cause a lot of problems when running fuel only. That drawing looks like an altered version of this one: But the changes to the drawing to make it fuel-only are incomplete - it should say that you have direct coil control disabled, and the terminal 11 wire should be removed.

2005? I believe that code must not have succeeded, because James has been saying now that you should not use the current code with more teeth than a 60-2 wheel.

I've cut off the hose barbs on a 280ZX FPR and stuck compression fittings on it. Russel makes a line of compression to AN fittings that would be just about perfect. Compression fittings use no flares, and are a bit easier since you don't have to deal with a flaring tool and the flare nut on there at the same time. There really isn't much room to make flares on there.