MSIIDIY 1.6 Initial Start up sounds like a WRX - Misfire?
 

Hi Guys,

I am literally in the home stretch on getting my Miata back on the road. I managed to get most of the bugs ironed except for this last one (hopefully). I can start the car up fine, however it sounds like it's mis-firing yet very subtle. Its acoustic tone resembles a WRX, if that paints a clearer picture.

What's wrong? I've captured a log during the initial start up in hopes someone with a keen sense can identify what I screwed up.

Probably a misfire. All misfire issues I've had have been ignition. What coils do you use and how old are they? What year is your Miata? How old are the spark plugs?

Pull the plugs and look for the wet one.

I am using the stock NA coils and they have been tested good prior to installing the MS. I have a 91. The spark plugs have less than 1,000 miles.

Pu da prugs. Loo fo da wet wun.

Hey Guys,

So I managed to do a few more things to help pin point my issue. Thanks for the suggestings about pulling my plugs. I pulled the plugs after a minute at idle. The outcome:
1-dry
2-wet
3-dry
4-wet

Then i checked each spark plug to ensure it's working, by grounding each plug to the valve cover and had my brother crank it over. All four plugs fired off.

After I ruled out any spark issues, I went to check compression on all 4 cylinder. 175psi on all 4 cylinders.

So, with all this information I strongly feel it may be my tune or my timing. Any suggestions? I've attached my tune to the first post if anyone would graciously take a quick look... =)

Post MSQ

Without any knowledge of your MS build. Or tune.

You have it set up in sequential mode for fuel. But its wired for batch. Or the other way around.

Or you have something weird in yoursetup.

What fuel injection harness. How did you build your MS.

Wild random ass guess.

I think i jumped the gun on this one. I forgot to test the injectors with a test light. so, injectors 1 and 3 doesnt fire off. injectors 2 and 4 fires off, which correlates with spark plugs 2 and 4 being wet.

I'll chase my wire for injector bank 1 and 3. Maybe its a broken connection???? i'll report back shortly.

Post your msq.

Are you using megatune, and all the other old outdated crap?

Here's more information:
- 1991 1.6 LNC NA RED, 5SP 2001 LSD
- Garret GT2560R
- Ebay intercooler
- 3" Turboback (open to atmosphere) with Electric diverter valve to stock exhaust
- ACT clutch/pp with OEM FW
- 460cc Rx7 Fuel Injectors (just cleaned, tested, flow matched)
- AEM WB LS1 Bosch
- Stock ignition
- New wires and plugs
- 175psi across all cylinders
- MBC

I purchased and built a MS2 V3 DIY kit. I've made my own jumper harness to integrate with the existing harness in the vehicle. I've also added a VTPS, AIT and Antilag.

I am using Tunerstudio MS Lite, V2.6.19

My MSQ attached. hope this helps. I'm presently armed with a multimeter testing the 1 and 3 injector banks.

One of your injector banks isn't working.

A 91 miata is batch fuel injection. Injectors 1 and 3 are wired together, and so are 2 and 4.

Somewhere in all of your stuff you didn't hook up the injector drivers correctly.

Looking at your MSQ you are setup correctly, so its either a hardware issue with the megasquirt or your wiring harness.

Couple ways to test this.

I suggest swapping the wires for injectors 1&3 and 2&4 at the wiring harness. Then trying again. If plugs 2&4 are now the dry ones and 1&3 are wet then it is an issue within the megasquirt.

You can also check continuity between the fuel injector plugs and your wiring harness.

Okay - pins 32/33 have continuity all the way to the injector plug. The plug also has continuity to ground. So, it appears I've ruled out that it's a wiring issue.... Sigh!

Megasquirt issue.

How is your wiring harness hooked up?

I pulled the female connector from another dead ecu. I used this piece and soldered it up to the db39 port and matched pin to ecu port accordingly.

Do you know where on the board I should focus for injector banks 1 and 3?

I want to know how you hooked the ecu connector to the db39.
I would scope the output of the injector driver. then the input. And see if the driver was dead.

@Ben and @Matt Cramer can be of help.

Thanks for the help. I've attached my mapping.

Do you have a Californian Miata?