Matt Cramer

Are you seeing an RPM signal?

Debug output slows down communications and can help loading firmware when you have serial noise issues. It can be worth a try, but I don't think the OP got far enough to where this has an effect.

Measuring RPM off alternator speed is open to pulley slippage or just plain errors in measuring the drive ratio. MegaSquirt counts pulses directly from the distributor or crank trigger and compares them to a precision crystal oscillator. You can check out the crystal's data sheet if you like - the frequency accuracy is under 30 parts per million. Unless the MS is misconfigured (such as telling it the wrong number of cylinders), if someone tells me the MegaSquirt's RPM reading does not match their tach, my advice is to troubleshoot the tach. Usually, I've seen two common reasons for a shop to dislike MS. One is that there's not as big a margin on reselling them. Two is that they may have had to straighten out a couple poorly done installs and it left a bad taste in their mouth.

Try using the bootloader jumper when you get that message - 9 times out of 10, that gets the code loaded.

No mods should be needed - you can run a stepper IAC off the S1 through S4 relay board terminals.

You're reading me correctly.

Pin 36 itself can take up to 5 amps sustained and more peak amps. The standard JS10 to IGN jumper has a 1K resistor in it, limiting current to 5 milliamps.

I suspect it just hasn't been tried. Whether it works depends on how much current is needed to trigger the stock ignitor.

You should be able to tune that out without using an IAC valve - in fact, we usually don't recommend using an IAC valve to fix a hunting idle as it will react too slowly. This can usually be dealt with using fuel and timing. Perhaps it's leaning out from higher IAT readings?

We have some generic MS dyno tips in this article: http://www.diyautotune.com/tech_articles/megasquirt_dyno_tuning.htm

As there's often a lot of questions about how to get the perfect idle, I've put together a lot of tips to idle tuning in a new article. http://www.diyautotune.com/tech_articles/megasquirt_idle_tuning.html Let me know what you think of this one - we may end up expanding the article a bit if you need more coverage of specific issues.

I only check up on the car when the mechanic runs into things he's not sure how to deal with (it's at a shop down the road from DIYAutoTune). Didn't hear any news yesterday.

Reason it was spooling appeared to have been a couple plug wires switched, lighting off the mixture in the exhaust. It also had a fuel leak and wasn't holding fuel pressure.

If you stick to high impedance injectors, MicroSquirt will run them just fine. With the Extra code, it is possible to make the WLED and ALED outputs serve as spark outputs to run wasted spark as well, although you'll need a pull up resistor. While there isn't much of an upgrade path for a MicroSquirt, it is fairly capable.

Just realized I was thinking of the wrong board - on V3.0s, Q5 is an injector driver, on V2.2s, it's the FIDLE output. What exactly is wired to pin 30?

This page explains how to set the jumpers for VR input. http://www.megamanual.com/357/intro.htm A HEI module is not needed if you install a coil driver in the Q16 slot - this wires up very similarly to a V3.0 except the IGN to IGBTOUT jumper has been omitted.

If the MS is controlling timing, I would not use the vacuum advance, but it can be simply disconnected. The ICM output can be treated as a points trigger, but I'd just use a V3.0 or V3.57 board and feed the signal in through the built in VR conditioner.

What is the resistance of your injectors? Are you running injector resistors or a flyback board?

If the tune isn't running as well as it can be, the engine just plain won't pull enough vacuum.

The LS1 mode does not work on the JimStim because the JimStim's LS1 mode is actually a toothed wheel mode. James wrote it before he had complete data on the LS1 wheel pattern.

Have you tried using MS2/Extra's dedicated LS1 mode instead of Toothed Wheel? Toothed Wheel sometimes has problems with the edge of the trigger being too near a tooth.

Do the MS injector outputs work on a Stim?

Try running a 1K resistor from a 12 volt source to pin 24 / the Mallory distributor output, and see if this gives an RPM signal.

This year, we've decided to combine the annual MegaSquirt get-together with the Classic Motorsports Mitty: http://classicmotorsports.net/events/mitty11/ So, like previous MegaSquirt meets, there's going to be tech presentations and the big names in the MegaSquirt world are going to be there. However, this time, it's going to be part of a vintage racing event at Road Atlanta. While there may not be as many Datsuns there as last year, when Peter Brock was Grand Marshal, there's bound to be a lot of cool Z cars, as well as a whole car corral for MegaSquirted cars. We have a page of our own on it here: http://www.diyautotune.com/events/megameet_2011.htm

Best way to deal with a burst of noise right while cranking is to increase Skip Pulses.