Cylinder 1 - no fuel
 

NB2 2002 with Reverent built MS2Extra

New built engine

I have accidentally been running on 3 cylinders. I mistook initial rough running for normal break in and me having to redo the autotune etc and iron out all the vac leaks etc. Yes I have gone for a test drive but was wary doing a scalding super vacuum beak in as it just didnt sound right.

So far this is my diagnosis

I am not getting any fuel to cylinder 1. - bad injector or bad wiring ?? At first I thought #1 was just a spark issue so I swapped with extra NB2 coils I have from a head I purchased.

Here is what I have done

Pulled plug wire 1 when running - no change to running condition

Plug is white/clean (all new plugs were installed with new build)

Plug fires when tested out of cylinder and ground to head

Said plug is still dry after brake cleaning it to ensure a good test and then running it for a minute (Does port injection always wet an injector when fuel is being sprayed - all my carburated bike/atv would do this so I'm making as assumption here)

Pulled front 3 injectors and tested with a 9V battery - all click, the one in cylinder 1 sounds a tiny bit different but very faintly so.

Ohms for all 3 I tested were around 15 if I remember

Swapped injector from #1 to #3 - reinstalled and still no change from #1 when plug wire pulled. Confirmed #3 still working fine by pulling plug wire and then engine got quite rough so it shows that this is not injector specific

Checked resistance on the yellow/black wire coming from injector 1 all the way to ECU plug at my Megasquirt 2E. I have continuity.


To do still tomorrow

Test compression at #1 but really that should not stop fuel from entering cylinder and making plug wet should it??

I want to try the built in Megasquirt injector testing but had difficulty tonight doing so. I'll look for clearer instructions tomorrow.

Any help or ideas? I'm hoping the MS tests will bring some clarity to if the #1 injector wires are fine.

Just thinking as I type - Hmm would the common to all 4 injectors blue/white wire show 12V when the car is on? I'll check that tomorrow.


I'm bummed but determined to get this resolved.

Swap an injector plug and see if it fires/sprays on that cylinder. Try setting to batch fire so the injector firing order doesn't matter. That could narrow down whether you have a harness problem.

I tried swapping injectors and it was not the suspected injector. I'll try the batch fire. I picked up upa set of NOID testers as well.

Thanks

Noid test confirms no signal at injector harness 1 but continuity on its yellow/brown wire to ECU plug

Trying batch firw now

How about power on injector 1?

Sorry I meant I plugged plugged the NOID in at the injector end and all but injector 1 was activating NOID tester lights.

Assuming you're keeping good sync, and that your wiring you checked is in fact good, it sounds like a hardware issue with the MS.

For good measure, I'd try the noid-light test right at the MS, probe the connector and confirm that cylinder 2, 3 and 4 act as normal, and 1 is dead. If true, I'd send the MS in for repair.

I'll try at the MS end. I'll look for a pinout diagram.

Can I fix the MS on my bench? Is it as straightforward as replacing a module? I'll die waiting weeks to get it repaired

You should contact Rev who built it. I dunno how different his is vs a normal MS2. Normal MS2 there are injector drivers and you could swap them out if one of them is bad. But if it's not working, you first gotta figure out what hardware is bad (inj driver, bad connection in ecu, plug on ecu bad, bad pin, cpu that drives the injector driver is bad, etc).

Also back in the day, sometimes the stupidest problems ever would be solved by reflashing firmware. Might also be worth a shot.

I've emailed him. I'll try a reflash.

I've forgotten where the boot jumper is but recollect that this set of 4 pins may be it. Does anyone have a Rev built MS2EXTRA that knows for sure?

If this is a 2010-era ECU (it is by the looks of it), then the most likely culprit is the U6 injector driver on the white microsquirt module. The drivers on the module of that era were prone to dying out of the blue.

That's a bummer...

I think this is it, honestly doesn't look too hard to get to, that part of the microsquirt isn't too crowded.

VND5N07 STMicroelectronics | 497-2481-5-ND | DigiKey

https://www.miataturbo.net/attachmen...ine=1435130425

I wonder if you could temporarily wire it up batch fire, while leaving it in sequential. I'd try it, can't hurt right?

part is readily available at digikey and swapping one off the board shouldn't be too hard.

actually I've come across 2-3 microsquirt cards where one of the on board injector drivers just wasn't quite soldered well into place and had a similar issue.

I'll check the U6 this morning for physical issues. Can I test it myself electronically?

I'll install the firmware first as I'm at 3.1 currently.

when running, you could check if the middle pin goes to ground rapidly, if it does, then check to see if INJ1 at the ECU connector is actually making it back to the middle pin.

A firmware question

I have a tacho output error. Which output pin is being used for that on my MS2E ? - note that it has VVT output to the VVT controller box so I dont know if that moves it to a different pin.

I also have an outstanding injector test that it wants to run and I can see the new GUI for testing under 3.3 but no way to remove the one from my last firmware 3.1 run.

MS errors are gone. I reloaded firmware choosing microsquirt, is that correct?
But now I only have injector signal on #3.
Put in the OEM ECU and get full proper injector signals.

Boo.

Anyone have have an MS3 with vvt ready to ship today? I'm lookin.

This is one I bought from you in 2011.

Do you have specific firmware for me to upload because this was a custom build? Can we try that before I send it back.

I've confirmed injector/spark all triggering when I reinstalled the OEM ECU.

I don't think it liked my firmware upgrade as now I have only Inj #3 firing.