The MR2 Owner's Club of New Zealand

Mammoth debug session this past weekend. A have always suspected that the Megasquirt wasnt reading the CAS right, especially with its two missing teeth, so I went ahead and modified my old distributor by grinding a single tooth off. Tested it by spinning it with a drill, and the MS reads it perfectly. Really solid RPM reading. Triggers as determined by the MS are a little iffy though, will need to talk to Jarad to see if we can improve that. Yanked 4 ISZ-FE coils from Zebra, in case my 3SGE ones were shot. The misfire remained. Examining the spark plugs revealed heavy fouling, and even a carbon bridge across a couple of them. A thorough clean brought their spark back - bench tested them one by one, so now I know that the ignition side of things is fine, so long as those triggers dont balls it up. I suspect that the engines getting too much fuel, though Im not sure how - the settings are the same as before, new wiring though and now has a resistor box in there. Ive tried adjusting the REQ_FUEL setting down, and that just results in lean burn and kick back on start. Increasing it results in it trying to run, but usually on only a couple of cylinders. Odd problem. Run out of time this weekend.

Figured it out. The Megasquirt pinout diagram I was using had spark outputs incorrect for my application. It was already in order 1-3-2-4, so when the loom went out and subsequently wired to the (correctly, as per Link loom pinout) to the coils, spark was in order 1-4-2-3 - double-crossed. So swapping the wires at the Megasquirt connector to 1-2-3-4 solved the order problem, verified with a bench test and direct observation of the spark.

After that, I put the plugs, coils, and distributor back in, brought down the cranking fuel pulsewidths a bit to try to mimimise flood risk, and then cranked it over while adjusting the distributor angle. At first, I had only injector 1 plugged in, and when I got firing attempt on that cylinder, plugged in injector 4. Cranked again, and it sounded like it wanted to run! Plugged in all four, and boom, fired into life - running on COP's properly for the first time.

So thats a major relief, and a big win. Now just to finalize some of the wiring, wrap it nicely and secure it, put the intake back together, and then test drive and re-tuning time - seems the resistor box and general layout of the resistor wiring has changed fuel delivery a little bit.

That's awesome news.

Wiring is normally straight forward but when you are merging two ECU setups together things can get complicated very quickly.

Went for first drive. Initially had issues with random RPM spikes, but sorted that out by switching wheel decoder routine from 024s9 to 025. Tweaked fuel a bit, runs well! Does blow the spark out under boost though, which is expected - Im using the old plugs that arent gapped for boost. Ill put the flash plugs back in and if the misfire goes away, problem solved.

Only thing left to do before this part of the project can be considered complete is to secure the coil packs, as right now they tend to move about and off the plugs.

The settings I used in the Megasquirt are:

Trigger angle: 63 degrees (no additions or trim)
Timing mode: Time based
Output mode: Inverted
Code type: Generic wheel
Base teeth: 24
Missing teeth: 1 (ground off, carefully, by rotary tool, afaik you dont need to choose a specific tooth)
Trigger positions: 1, 7, 13, 19
Trigger returns: 3, 9, 15, 21 (though not used with Time based triggering)
Dual dizzy mode: Normal
Wheel decoder routine: 025 style
Dwell cranking: 3ms
Dwell running: 2.5ms
Min discharge: 1ms

Also, not sure if its made a difference, but Ive set cranking speed to 400rpm. Anything above this, the MS will consider "running", and the idle is currently set about 900rpm, so well above that. Car starts practically instantly, and sounds very healthy, though I deleted idle up stuff, so requires a bit of foot control to keep it going when cold. Is fine when warmed up.

This weekend, I modified a bigport 16v spark valley cover to serve as the mounting plate for the COP's. Took seals from the 1SZ-FE coils, now that Im using 1G-FE units instead (taller, more connector angle, can get 6 at once from one donor car), and glued them to the under side of the spark lead holes - there is a bit of a lip, and these specific seals snap in to place on them perfectly. I then placed the COP's in place, with the angle I wanted them to sit at, and drilled bolt holes. Then ground down some nylon spacers, with a notch to let them sit nicely over the raised square bit. Glued nuts in place for the bolts, and job done. Works super well.







Swapping the plugs for the BCPR6EIX-11 didnt stop the misfire. Hmmmm. I also tried adding a 10k resistor in line with the VR sensor signal. While it didnt help the misfire, it did result in the Megasquirt remaining online when it occurs, so I will leave it in. Ill try adding capacitors across the coil supply lines, but kinda running out of ideas now. The problem occurs very reliably at about 4500 RPM and 150kpa of boost at WOT. I do have a suspicion that the main relay is insufficient for the current demands when coming into boost. The way I designed the power distribution wiring, the main relay feeds power to all other relays - injectors, coils, pumps, ECU, everything. Its a 100A unit, perhaps I need larger.

Can you go past 4500rpm when it happens? I would have thought 100A would be enough

I can if I feather the throttle, so that it doesnt build boost. Can get all the way to 6500, probably higher.

Ok, adding more dwell on the coils solves the misfire. Yay. I will swap out plugs to BCPR7E anyway.

The Megasquirt still tends to turn off a bit, and the main relay is the prime suspect. A few times now, Ive gotten no juice at all to the engine bay, and tapping on the relay brings it back. Its a cheap Chinese junk relay. Im going to upgrade to a 150A unit from Jaycar, see if that improves things.

Awesome work on this custom stuff. It's been very interesting following this build and seeing all these issues and testing you are doing to fix it.

I say hit it with a bigger hammer if it doesn't work.
Not a good sign if you are tapping on the relay to make it work. Hopefully the better Jaycar unit works out. Can you power things from more than one relay? So use one relay to switch 2 relays and spread the power? Or is it just a dodgy relay causing the issue?

vrtigo wrote:Ok, adding more dwell on the coils solves the misfire. Yay. I will swap out plugs to BCPR7E anyway.

The Megasquirt still tends to turn off a bit, and the main relay is the prime suspect. A few times now, Ive gotten no juice at all to the engine bay, and tapping on the relay brings it back. Its a cheap Chinese junk relay. Im going to upgrade to a 150A unit from Jaycar, see if that improves things.

Sounds like a dodgy relay then. If Jaycar asks a ridiculous price give Ashdown-Ingram a ring

GDII wrote:Can you power things from more than one relay? So use one relay to switch 2 relays and spread the power?

My main relay powers the entire fuse panel, which itself feeds secondary relays - one each for injectors, coils, pumps, and one left over that was going to be for the starter. The fuse block is powered from a single battery feed, so I didnt have a lot of options when designing the layout. Works super well though, just gotta be sure that main relay can handle continuous loads, and its rated max current.

GDII wrote:Awesome work on this custom stuff. It's been very interesting following this build and seeing all these issues and testing you are doing to fix it.

Thanks for the feedback dude. Ive always considered myself a bit of a Macgyver, and that extends to my car modification as well, it seems. Its like what I want the car to be is a giant puzzle, and just needs to be solved to get to the end goal. Sequential ignition was always part of that, as was turbo, and both of those need *significant* supporting modifications to get anywhere near. Ive learned a shitload in my 8 years of toying with cars!

Have you looked at the current demands on that relay? Generally coils, injectors, ECU, engine ancillaries would be around 5 amps (unless VVT), and fuel pumps somewhere around 7-10A depending on how hard you're working them and how big they are. If you're running a large electric water pump or your radiator fans through it, these can be 15-20A or more but I still doubt you're anywhere near 100A.

I would actually stay away from those Jaycar 150A relays too, like most Jaycar products they are Chinese junk, which is OK for some stuff but in this case I would suggest it's not worth it. I have actually tested those on something once and found them to be more failure prone than a good 30A relay. You can get relays in the same form factor from reputable manufacturers through RS components, any of these would probably be a good choice:
https://nz.rs-online.com/web/p/non-latc ... s/8113097/
https://nz.rs-online.com/web/p/non-latc ... s/5352564/

or if you're adamant you need more than 100A, there are these ones which are very good, although I can't see anyone who stocks them in the SPST configuration, only SPDT
https://www.waytekwire.com/item/75672/P ... SO-Relay-/ and you would probably have to get them sent via youshop or similar from the US

good work on sorting out the misfire; I was going to suggest more dwell after having the same issue recently and solving it in the same way. Out of curiosity, how much dwell are you running on them now and what were you running?

Just looked through the pictures and saw your relays - if you want to stick with a relay with studs for the power connections then these ones are good, and I think you'll get free 2 day shipping on them to NZ (just remember to get a connector for the switching inputs too)
https://www.mouser.com/ProductDetail/TE ... 2A2001B200

Currently running 3ms of dwell. It was a red herring actually, though - the misfire returned. I have now solved it once and for all by reducing the spark gap even further - down to 25 thou now, which is pretty small, but hey, it works. No sign of misfire through to 10psi and high RPM. I may try reducing dwell back to 2.5ms, but 3ms definitely seems to work, and hasnt killed any of the coils yet.

Replaced the relay with the Jaycar 150A unit, and all power delivery issues have disappeared, too. For now, its good enough, but I had to reduce the wire gauge significantly, down to 10G, but ran two wires to make up for it. So far, no sign of problems. Eventually I will probably try something like the relay you linked, thanks for that!

The relay value is more for future proofing than any actual expected current demands.

In other news, the yellow adub has developed what I suspect is a blown head gasket. This morning, went to start it (to go somewhere important, of course), and it fired once, and then nothing, and the sound the cranking made was as if the spark plugs were missing. All of them! Very odd, so began a morning of debugging. Compression test on all cylinders measured about 30psi, if that, which was super bad news. I still cant understand why all cylinders would be affected in such a way. I did "fix" it however, by pouring a little oil into the cylinders. Doing another set of compression tests returned 150 or so, and not long after it fired into life. Lots of smoke though, as you might expect, however it now billows smoke on accelleration, and I can see steam/smoke coming out of the exhaust gasket seams when under the car. Not exactly what I need right now, but at least I have a good (actually, perfect!) engine ready to swap over. Will need to bump up the schedule for that now, as its my daily into work!!

Its never easy, is it?