[Jason Rouillard]

My vr- is connected to vr- on speeduino

[PSIG]

+1, and I wire them:

1. VR+ to Speeduino VR+
2. VR- to Speeduino VR-
3. Shield to Speeduino power ground

I always use two grounds on Speeduino, sensor ground and any others for power ground. Only signals and sensors on signal ground (a.k.a., "signal return"). This helps to separate small signals with high-current and noise.

[Jason Rouillard]

Shield to Speeduino power ground

Speeduino power ground it's like battery ground ?

[PSIG]

It is common or chassis ground, a "star" or collected single ground point, such as the engine block providing equal grounding for users. The equalized chassis ground is then connected to battery ground (-).

ECMs using Speeduino typically have multiple ground pins or wires, usually two VR-, and 3 or 4 "GND". While that may seem odd, many factory ECMs may have 6 to 12 separate ground wires, or more. I choose one of those for only signal grounds, and the others are "power" grounds to carry high-current or noisy stuff like the board power, injectors, etc.

This is an example (one way, not the way or only way) of a grounding scheme I might use to minimize noise, ground loops and ground voltage offsets: Re: Recommended wiring practice

[Jason Rouillard]

Probably my problem come from my grounds.

Currently my speeduino/engine is wiring like this :

Speeduino is directly connected to battery (pos throug a key switch and negative directly).
My ICM is grounded on engine head and my engine directly to battery.

All of sensors are grounded on pins (Ground on speeduino).

My shield of crank sensor wires is grounded directly to battery.

I read on internet and yours responses and if i understand, the best things is to make one ground point for all grounds. So, on engine or directly to battery !?

Some eom ecu have many grounds. My speeduino have only one ground (ground from power). Do i need to add a another ground to speeduino ? Like grounded directly pin 9 to engine or it's correct with only with supply ground ?

I have speeduin 0.4.4b

wiki.speeduino.com/en/boards/V04

[Jason Rouillard]

I am not sure if I understand all ground on speeduino...

On the PCB, 3 grounds connected together (Pin 9,10,12). The 4th ground doesn't seem to be connected with the other 3 (pin 23).

Can i use the pin 23 to ground sensor or i need to wire this pin to my ground star point ?

[PSIG]

That's fine. Each power ground wire should be run separately from the ECM to the star ground on the block and not spliced before. The chosen ECM sensor ground terminal does not go to the block.

Ensure the chassis and any other grounding point for devices other than the engine block (instrument panel, transmission, etc) have good ground straps to each other and the block to carry ground current, so ground does not try to go through the ECM to get to the device. A typical car will have many part-to-part ground wires or straps for this purpose. This is why we ground at one point, so the ECM ground wires are not accidentally used to pass ground to other parts of the vehicle or chassis, affecting ECM electrical and signals.

The dashed lines on the PCB layout are connected, but not shown. Commonly by ground layers, copper fill, or other that is not an obvious trace.

[Jason Rouillard]

That's fine. Each power ground wire should be run separately from the ECM to the star ground on the block and not spliced before. The chosen ECM sensor ground terminal does not go to the block.

Ensure the chassis and any other grounding point for devices other than the engine block (instrument panel, transmission, etc) have good ground straps to each other and the block to carry ground current, so ground does not try to go through the ECM to get to the device. A typical car will have many part-to-part ground wires or straps for this purpose. This is why we ground at one point, so the ECM ground wires are not accidentally used to pass ground to other parts of the vehicle or chassis, affecting ECM electrical and signals.

The dashed lines on the PCB layout are connected, but not shown. Commonly by ground layers, copper fill, or other that is not an obvious trace.

I don't have plug on transmission. I only have wiring harness on engine. No cluster, no alternator, etc..

I changed all of my ground. My shield ground is connected to speeduino ground. I also connect speeduino ground directly to engine like star point. I cleaned all ground. I did a bad ground with ICM. On wiring diagram, it's write "IC low ref" and it was grounded directly to engine. I fixed it and now it's grounded to Speeduino.

But, with theses modifications, i also have noise at cranking and engine make some bang into exhaust.

I also need my 330 shunt for start when engine is cold and when is hot i don't need shunt to start and run.

The engine revs up a little more (6700 rpm) My hard rev limiter it's at 6800, but i think i cannot reach it.

I also take thoot logger when cranking few seconds, many seconds and when engine run.

[Jason Rouillard]

I read this article : https://www.diyautotune.com/support/tec ... te-logger/

In this article, there is an example of GM7x with tooth logger. All image are nammed to find quickly the test done.

I did somes tests to find the noise.

I did tooth logger without spark plug to kept same speed of engine rotation.

I tried without sensor, with filter, with rising/falling and with a signal from my ICM and i has all of time same thing.

[PSIG]

I tried without sensor, with filter, with rising/falling and with a signal from my ICM and i has all of time same thing.

Exactly. Keep in-mind, the Tooth Logger and the Composite Logger give different info. The Tooth Logger only shows time in any condition, high or low. So, the longer it is low, the taller the bar, and the longer it is high the taller the bar. Yours is a good example of the effects, and how the timing only shifts, as either high or low signal, Rising or Falling, the duration (time) of the wide teeth and gaps are the same, inverted or non-inverted. A Composite Log would be different info.

Where we see issues ("double bar") with the Tooth Logger is when the signal voltage drifts upwards or downwards in a "wide" space, triggering a high or low early, where there is no tooth (missing). Again, this is either incorrect polarity or setting to read the wrong signal edge. An irregular wheel may read perfectly in any combination where there is insufficient time for the signal to drift high or low early.

Finally, we say "correct polarity" so we know which sensor signal edge will be sharp and most accurate. And "correct edge setting" for the specific conditioner module to read that correct edge, that will not drift timing at high-rpm. Four ways to set up VR, but only one is optimal.

For an irregular wheel such as the GM7x, test your sensor for polarity separately, and connect to the proper VR inputs. Set your Trigger Edge for the specific VR conditioner module you are using. Then set your timing using Trigger Angle, with a timing light.