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Help with building your Speeduino, installing it, getting it to run etc.
By Cylinder 8
Ah, that explains why it didn't work when the rev counter was connected directly to the tacho output.

Just to clarify, I need to connect two wires to the red/white rev counter wire: one to the output of the ECU, the other to a 12V supply via a 1k resistor?
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By Chris Wolfson
You have some problems that could be ground related. This often manifests in hard starting and un explainable behavior while running.
Best is to make a schematic only for your ground connection, so you see what path might be shared by different users.

As a first, cheap insurance it is a good idea to run an additional ground wire (like 1.5 mm) from battery negative to the engine, a second one from battery to the chassis. This way you will reduce resistance in the factory ground wires close to zero. Sometimes, there are ground issues that only disturb operation during cranking. In such a case it can happen that the additional ground wires start to get warm, fume or even glow. Then you know there is something wrong.
Your tacho acting strange is a strong indicator for such a latent problem.

It takes you 10 minutes and parts for 1$ to do this and it can do no harm.
By Dagaz_Psi
Heres the stock tacho running on speeduino default settings with 1k pullup resistor.
He's tacho isnt working properly because its not wired up correctly.
Yes from what i could read in the uac link you posted it says you need a 12v pullup and 1k gets you pretty close, see image above. And both to red/white.
And i Think your cranking issues is more related to your tunerstudio settings.
By Dagaz_Psi
So I have been thinking and testing some stuff out today.
1. For some reason when the uln is switched of and its constant power on the output pins it feeds that power back trough the flybackdiode witch pulls it to ground.
that results in everything the uln controls turns on.
the solution is to cut of the last leg on the right side, indentation pointig up, the COM leg.

2. The tacho would not go past 6500rpm with a 1k resistor but with a 10k it worked descently up to 7400rpm.
I had a osciloscope hooked up and there were no diffrence on the squarwave with or without the Coms leg, tested the tacho at 1000rpm increments.

3. To get the IAC to work I had to put it in reverse setting and somewhere between a 30-40hz.
Thats all folks.
By Dagaz_Psi
IAC update: Was thinking out of my ass yesterday, for some reason i got the idea that it needs more air when its cold.

To get the stock IAC to work properly a 1n4002 diode is needed for flyback.
Its about -40v without flyback diode and the solonoid will work but the other way around i.e idle going down when it should go up.
Now its working happily between 25-30hz and idle valve direction set to normal.

The 1n4002 is the diode bosch uses for IAC flyback on the stock ecu.
If somebody wants to use it I can post images of were its located on the stock ecu. ( it differes with ecu numbers)
By dazq
Dagaz at that low frequency how is the resolution? I found I could only get about a 15 step resolution, but that was at 110/120hz which was what the OEM ECU used for its frequency.
By Cylinder 8
I ordered a load of 1k resistors and got the rev counter working using one of them this morning. It over-reads a tiny bit, like the one in the picture, but I can live with that.

I've read about the diodes and idle control valves but I'm happy with how well it idles using nothing but ignition timing control. I've got some blanking caps for the hoses so I'll be removing the valve completely soon.

The other news is I had the emissions checked yesterday (the main reason for fitting the Speeduino in the first place) and it passed. My garage then kindly managed to fit it in for an MOT straight away and it passed with no advisories. :D Not bad for a 22 year old car with 167k.

All that's left to do now is have it professionally mapped, which will hopefully be in the next week or so.
By Dagaz_Psi
Dazq you are right it sould be at 120hz, but for some reason when i tested this out last time it would just stay open at 120hz.
Testing it out right now at 120hz and its smoother.
When I bench tested this out I pulled one from an iceracing car that had been sitting for almost a year.
Now its been humming away on my desk for a couple of hours when I been testing out some other stuff and seems to do a better job.
If your meaning dutycycle I got 15% diffrence between open and closed at 120hz, same at 30hz.

Cylinder 8 nice If you want the thaco to be more exact you can switch out the 1k resistor for a coil from a relay.
Messaured the stock tacho output and its 28-40v.
Sweet its a 98 then? Got a 945 -98 as my daily, its at 22990 miles 37000km and it also past mot a month ago. Or as it called in sweden, cartesting (bilprovningen). still running lh 2.4 tough.
Why didnt it past smog in the first place?
By Cylinder 8
Dagaz_Psi wrote:
Sat Nov 28, 2020 7:43 pm
Why didnt it past smog in the first place?
I had the LH2.4 remapped because of the bigger turbo and injectors my car has. It wasn't remapped very well and was running really rich under light load, about 11:1 when it was emissions tested.

It turns out my starting problems have returned. Changing the skip revolutions during cranking to 0 (which I think I mentioned on here before) seemed to work most of the time but sometimes it just kicks back as it fires the spark plugs at the wrong time during cranking.

I've had a look at the tooth log to see what's happening. This is how it looks when it's running, which seems pretty good to me:


But this is how it looks during cranking:


Clearly the two smaller spikes in between the main ones are what's confusing speeduino. With skip revs set to 0 it can misinterpret a smaller spike as the gap in the flywheel teeth and try to start with the engine in the wrong position. With skip revs set to 1 or more the smaller spikes are causing it to lose track of where the engine is so it can't start it. It just turns over and over with no engine speed showing and no signals going to the injectors.

I have no idea where these smaller spikes are coming from. I've tried every different level of signal filtering in tunerstudio and none of them seem to make any difference. Strangely, if I do get the engine to start it will then start fine every time for the rest of the day. This only happens when it's completely cold. Any ideas?
By Cylinder 8
I've just done a test to see if it's related to the starter motor load. I took the spark plugs out and turned it over with no compression. This was the result:


So it looks like it's related to the voltage drop through the car as the starter motor comes up against the engine compression, or something related to that. I've already fitted a much bigger battery than standard so I don't really know where to go from here.
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