Help with building your Speeduino, installing it, getting it to run etc.
User avatar
By Eric H
#45295
theonewithin wrote: Wed Sep 09, 2020 4:07 pm Tooth after missing at high RPM looks funky to me...

It shouldn't be shorter than the rest...
I can't really do anything about that. It's a VW with a big wheel inside the engine attached to the crankshaft. It should be well within the timing window.
Image

I get to work on it more tomorrow, the dyno is booked for the 15th, with a race on the first weekend of October :shock:

I did find I did a dumb, the VR shielded cable ran about two inches away from the coil pack. :oops: When I run it tomorrow I'll see if that was the cause.
#45298
Hello, good afternoon, I am running with a v0.4c board and I have the same problem on a Toyota 1JZ and 2JZ (2005 firmware) and a Mercedes M104 (2008 firmware) (all 3 motors with original inductive sensor and phonic wheel original with wasted spark). It gives me the same readings as the previous images. Where should the 4.7 ohm resistor be installed?
Greetings and thanks
PSIG wrote: Wed Sep 09, 2020 11:30 am Random: Misfires, preignition, bad timing, etc, can cause loss of sync when Speeduino is confused by the signal positions. Check your logs for oddities or the effects of them, such as a spike in your RPMdot, indicating when and where you got one. You can expect a spike at sync loss, but if you find other (usually smaller) ones, they may point to an issue that only causes sync loss at a certain magnitude.

Verify your jumpers are set for both signals "VR" so they both go through the DSC. This prevents the 2nd channel floating and possibly interfering if the Hall signal is bypassed (direct).

The added cap can slope the signal voltage, causing lower signal amplitude. If you don't need it, don't use it.

Some VR/wheel combinations are crazy voltage. If the VR voltage gets too high, again it can cause losses. Add a 4.7K resistor to the input and check losses.

No, it's not common.
User avatar
By Eric H
#45308
Follow up:
The engine is much happier with a 4.7K resistor across the VR sensor. It's not perfect but I have a misfire now and then. I'm going to up the dwell a little bit and do more testing.
The car has gone from horrible to tuneable. Hooray!
#45321
I did not want to make a new thread since my problem was similar to that of this thread, I also installed the 4.7k resistor today and it improved a lot and practically no longer the signal is desynchronized ... but what calls me the attention is that in the Wiki they speak of a resistance of 10 K (I think I will still do a test with 10K)

https://wiki.speeduino.com/en/boards/VR_conditioner

I really appreciate the help from "PSIG" on the resistance since in my car (m104 Mercedes engine) it improved a lot and I hope this week to do the same tests with the other engines that have the same problem.
And I'm glad you could fix the problem on your car Eric H

Regards
User avatar
By PSIG
#45337
I'm glad you both had improvement with the added resistor. In this case, either voltage can be shunted (3W or larger resistor across VR wires), or the VR power reduced (resistor in-line anywhere on VR+ signal wire). The voltage sensing signal conditioners (MAX, LM1815, LM358, etc) must use the shunt method, while power-sensing (DSC) can use either method, although inline resistors are typically easier to experiment with.

The original resistance is kept low, as it would suck to begin with too much resistance and no cranking signal on weak setups. So, most common is needing to add resistance for high-rpm on stronger setups. The general goal in resistor selection is to use the highest functional resistance that reliably triggers at low-battery (slow) cranking speeds. 8-)

David
User avatar
By Eric H
#45361
In another followup, I replaced the NGK copper spark plugs (gapped at .028) with NGK Iridum plugs gapped to .028.
It was a total disaster. Constant misfiring under load, 40+ sync losses in a single pull.
Put the Coppers back in and all is well. WTF? Iridium is supposed to have better ionization.
#45368
Eric H wrote: Mon Sep 14, 2020 8:14 am In another followup, I replaced the NGK copper spark plugs (gapped at .028) with NGK Iridum plugs gapped to .028.
It was a total disaster. Constant misfiring under load, 40+ sync losses in a single pull.
Put the Coppers back in and all is well. WTF? Iridium is supposed to have better ionization.
That sounds like electrical interference. Did you change anything else before that problem occurred? Are the iridium plugs resistor type plugs?

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