Matt Cramer

What's the minimum number of steps you have it set to move the IAC at a time? Try increasing it from 1 step to 5 or so; we've found some types of IAC valves seem to get stuck if you don't try to move them several steps at a time.

If you're powering the wideband, I would not use that wire - I'd probably grab 12 volts from some point in the fuse box.

Look for an Explorer or Aerostar with the V6 from the early '90s. The module is about the size of a pack of cigarettes and usually bolted to the passenger side inner fender in the engine compartment.

Ok, you might want to try the low Z noise reduction mod. Clip the center legs of Q9 and Q12 off the PCB, then solder a wire to these center legs on the transistor. Wire both of these to a separate 12 volt source. This routes noise from the injector flyback away from the Megasquirt's own 12 volt supply.

Are you running low or high impedance injectors?

Pretty rare for U4 to be burnt like that. I would check to see if there's any damage to Q1, Q5, Q14, and Q15 as well if that happens. That is the injector driver circuit.

Having the IG LED lit could either mean that you have burned Q16, or it could happen if you have Spark Output set to Going Low (normal) which might damage the BIP373 or might also damage the coil.

Actually, you're seeing power coming into the + side of the injector, traveling through its coil, and coming out on the - side of the injector.

That's the IAC relay. If you've configured it for a PWM IAC valve, you need to remove and jumper the relay. The IAC relay is only used for on/off IAC valves.

As near as I can tell, Chrysler never built an ignition system with external coil drivers; they always integrated the drivers into the ECU. The only examples of "Chrysler" engines I've seen that had both EFI and an external ignition module were ones built by Mitsubishi.

If you have an RPM signal, yes. If the RPM drops out, the PW setting will stay on what it was doing before the RPM dropped out for a few seconds before falling to zero. Do the injector LEDs on a Stimulator blink when you bench test the Megasquirt?

The 240SX has the same type of setup with unequal length slits, and we've found the 280ZX mods work for it.

The Optispark pretty much is an 8 cylinder version of the L28ET distributor, from what I've heard. You'd ground the Reference Low and wire the Low Res signal to the MS. Please let us know how this works out.

That is what the light should do if the engine is not turning. The voltage on the MS side will briefly drop to near zero when the injectors fire. Do the injector LEDs work correctly on a Stimulator?

Unless you have wired up a fuel pressure sending unit, the reading from the fuel pressure log is going to be something random. Could be reading electrical interference from the O2 input, even. The Megasquirt doesn't use this reading for any of its calculations. You could ground the spare ADC port through a 1K resistor if it bothers you, but really, there's no need to look at the fuel pressure log anyway.

Ok, try decreasing the Controller Authority percentage to zero, and get the AFR in the 2500 to 3000 RPM / 45 to 50 kPa range to match your target. This data log shows that you've got a case of a somewhat aggressive O2 correction and a VE table that's just a little bit out of tune. You can turn the controller authority back on once the VE table is fixed, though I wouldn't go over 10%.

If you want to upload it here, put it in a ZIP file along with your MSQ, make a post in Advanced Mode, and click the Manage Attachments button to post it.

The instructions are written around MS2 Bowling & Grippo code; some of MS2/Extra's terms are different. With MS2/Extra, set it to Basic Trigger under Tach Input / Ignition Settings, and Standard Dwell under More Ignition Settings.

Yes, it is. No. Either end of the wire works just as well.

It may be time for an update. There's quite a few MS-II installations out there and it has been pretty stable. HEI modules had something of an advantage over the old VB921s in that they're a bit more reliable, but the BIP373s are about as tough. The HEI modules are kind of an easier way to get spark control with a V2.2 board, but that's about it.

Please, I need the data log itself, not a screen capture. There's information in the data log that the screen capture doesn't show.

We've put together an article (with a lot of help from Moby and many other denizens of this board) on how to use MS with the 280 ZX Turbo distributor here: http://www.diyautotune.com/tech_articles/how_to_megasquirt_your_280zx_turbo.htm Many other standalone systems can use the 280ZX distributor as well. Other ones that come to mind (in strictly alphabetical order) include Accel/DFI, AEM, BigStuff3, FAST, Haltech, and the Holley Commander. The fact that the Nissan distributor is a close cousin to the Optispark doesn't hurt...

Megasquirt normally ignores the fuel pressure; it's just used for logging. Do you have a data log and MSQ that you could post? These will provide more information than a screen shot. However, my gut feeling is this is a combination of a somewhat out of tune VE table with a large amount of O2 correction: This will produce the sort of bouncing behavior you're looking at as the system overcorrects and swings back and forth.

It does have a couple of unusual components on there, but this one appears to be set up for fuel-only operation and does not have ignition outputs or any extra outputs enabled.

Those are the ones you'll currently see "in the wild" at the moment. There's also a MS1 B&G HiRes and an MS1 B&G Dual Table version. I don't think I've ever worked with a customer who was running either one of these, as most people who want these features go straight to the Extra codes.