Megasquirting my 4AGE

[whynot]

It could be the speed you are turning the cas at. Sometimes you need to lower the trigger threshold voltage as the signal generated by the cas at low speed is pretty small which can cause intermittent spark and difficulty starting the car. Saying that if there is interference coming from somewhere and you lower that threshold voltage then you can get miss firing. Best way to check this is with an oscilloscope.

[Vertigo]

Was afraid of that I dont have one, but definitely have wanted one for some time. Might be time to splash out and buy myself a present. A multimeter is just not cutting it!

[Vertigo]

Progress. Redid my CAS wiring and even wrapped it in tinfoil, and now I seem to be getting a reliable RPM. Timed the CAS correctly and Im 99% sure the injector and igniter wiring is correct. Cranking the car over results in it not starting, but popping and galloping like it wants to run. Turning the CAS doesnt help much, its in the best spot where I have it. Sometimes get knocking. I wonder if, even though Im getting a good RPM value at the ecu, the signal is noisy enough to not provide decent trigger points. Hmmmm.

Edit: Reducing the resistor pack value by half makes it REALLY want to start, it even hobbled on its own for a bit.

[Crucible]

Have you checked to see how much spark you have at the plugs and put a timing light on it to see where its actually firing on the crank marks?

[Vertigo]

When it was on the bench, produced good strong spark. Trouble with a timing light is that it doesnt run for long enough for me to get there and check the timing, plus its a real bitch to do this on an AW11! Ill have another go tomorrow afternoon, for now Ive put the dizzy back in.

[mega4a]

are you using a diyautotune loom? from what i have read/heard is that the trigger wire is weak and picks up noise. my wire has a max shielding around it aye quite thick maybe try that ?

[Stu-]

I've got plenty of spare shielded trigger cabling if needed

[Vertigo]

Heading to my mechanic friend tomorrow to use his oscilloscope, see if I cant track down the source of the issue. If it turns out to be the CAS cable, Ill take you up on that offer.

[Vertigo]

CAS cable looks to be solid, and actually there is no noise on the traces at all. What might be causing a problem is the last tooth, which is giving half the peak that the rest are. I did nick that tooth a bit while grinding off the missing one. Looks like I need a new trigger wheel.

First, cranking with no spark plugs, to remove variation.


Second, with plugs in.



That said, I did get it to run for about 5 seconds, albeit very badly on what sounded like 2 cylinders!

Edit: New plan, Im going to grind off the rest of the damaged tooth and set the ECU to expect 2 missing teeth.

[Vertigo]

I might have found an issue, maybe the issue, Im not sure. In my AW11 manual wiring diagrams, the injectors are paired 1-2 and 3-4. But when I inspected the wire colors in my factory loom, it seems they are paired 1-3 and 2-4. This is pretty odd. Having thought I found the problem, I swapped the no2 and no3 injector plugs, but that didnt help. Now that I think about it, it probably wouldnt have, if it is working fine with the factory ECU, which works in exactly the same manner.

[Stu-]

They're group fired anyway, just divided into two drivers to keep the current draw low.

[Vertigo]

Does it not really matter which cylinders get fuel at which time? I wouldnt have thought that.

Im taking the whole shebang down to Jared this weekend, he can find the problem, Im done with it! In and out 6 times now, sick of the whole process!

[Stu-]

Nope, they fire at the same time.

Just fit a Link

I've installed all sorts over the years Link, Autronic, Haltech, Megasquirt, Microtech, Wolf 3D, Emanage etc. Not too many Megasquirts (4-5) but I haven't had one go plainly from start to finish - admittedly its not always been the ecu at fault but they do seem to be quite susceptible to triggering issues and needing high levels of filtering in my experience. Might just be the versions (I haven't supplied them). Seems to be fine once going thou.

Hope it all comes together for you

[Vertigo]

The AW11 wiring diagram in my manual shows the injectors all supplied 12v through a resistor, splitting into pairs which are then controlled by the factory ECU. Are you saying that all 4 injectors fire at the same time on every stroke, or that the pairs fire alternately? Just for clarities sake - likely the latter.

Someone must have messed with the wiring colors in my loom at some stage, because 1-3 and 2-4 does NOT sound right, yet it works fine.

[Stu-]

The ballast resistor is just there to reduce the current draw on the injetors 12v side. Its common that one or more need to be setup for low impedance injectors for most aftermarket ecus - there are a few that dont need them, usually higher spec versions. You can work out the size the by using ohms law.

Yes they all fire at the same time not in pairs.

[Stu-]

Oh 1&3, 2&4 is common grouping for Toyota ecus.

[Vertigo]

Wow, really? I expected it to be more sequential than that! At least batch fire to match ignition, hah!

[Stu-]

Nope. Blacktop injectors are wired individually so I assume they are run sequentially but the 16v injectors are group fire.

[Vertigo]

I didnt actually mean sequential, I meant given that the wiring splits the injectors into pairs, and those wires feed into the ECU seperately, youd think that the two pairs would fire alternately. Whats the point otherwise! What was Toyota thinking?

Have just tested this by swapping the plugs for no2 and no3 injectors, and the car runs as good as it ever has. Will leave it like this now.

I think I know what the problem has been all this time now. My Megasquirt fuel settings are alternate firing, 2 squirts per engine cycle. When you think about it, thats horribly wrong, and explains why its sounded like its been running on 2 cylinders and hobbling.

Two solutions to this:
1) Stay on Alternate injection, but increase to 4 squirts per cycle
2) Switch to Simultaneous injection, 4 squirts per cycle (emulating the function of the factory ECU, now that I know)

I think Ill go with the latter, at least for now. Watch this space!

[Stu-]

The term is batch grouped injection. Its designed that way to reduce the current draw for each injection drive but still fired all at once. Even at idle/low rpm the injectors are pulsing fairly rapidly so fuel doesn't sit behind the valve for very long at all. Most older ecus with 'sequential injection' actually revert to grouped fire after a certain rpm. If you can be bothered you can sit down and work out the load on each drive by measuring the injector resistance and ballast resistance and then using ohms law to give you the current.

Great that you got it all worked out. Now for tuning and lots of boost!