Second firmware live stream happening this weekend: viewtopic.php?f=13&t=3992
Help with building your Speeduino, installing it, getting it to run etc.
User avatar
By zoidberg
#42980
Hi there
i have built my motor with wasted spark and a 8 -1 trigger wheel in the distributor and my ignition timing is jittering like hell.
I also have a condition where the motor tends to run a bit lean, but that is tuning i think to optimize that.

is 8-1 even possible or is that too little tooth?
User avatar
By PSIG
#42989
Please define "jittering like hell". Timing jitter is commonly from a few sources, but could be one or more of many factors. Common ones are incorrect sensor polarity, or incorrect trigger edge setting — or both. The wiring, noise or incorrect settings "confuse" the ECM.

Other causes can be mechanical, such as the wear and clearances in the distributor drive, or looseness in the points plate or shaft/wheel portion of old advance mechanisms (if equipped).

Low tooth counts and mechanical drives can cause some loss of accuracy, but "jitter" should be minimal in an 8-tooth distributor. I have seen around 2 degrees (usually less) in a similar 8-tooth setup at low-rpm idle. Less at higher rpm.
User avatar
By zoidberg
#42993
PSIG wrote:Please define "jittering like hell". Timing jitter is commonly from a few sources, but could be one or more of many factors. Common ones are incorrect sensor polarity, or incorrect trigger edge setting — or both. The wiring, noise or incorrect settings "confuse" the ECM.
Hmmm i could try to trigger on the rising edge of the signal, maybe that helps.
The jitter is really quite a few degrees. I will have to remount the distributor trigger to shoot a video.
The sensor polarity should be right, as the signal looks fine on the oscilloscope.

PSIG wrote:Other causes can be mechanical, such as the wear and clearances in the distributor drive, or looseness in the points plate or shaft/wheel portion of old advance mechanisms (if equipped).
But that wear should have resulted in bad timing with the points ignition as well, which i didn't have. The advance mechanism is locked out as in wont ever work again with that distributor.
PSIG wrote:Low tooth counts and mechanical drives can cause some loss of accuracy, but "jitter" should be minimal in an 8-tooth distributor. I have seen around 2 degrees (usually less) in a similar 8-tooth setup at low-rpm idle. Less at higher rpm.
Hmmmm
Another thing could be that i went for cylinder 1 exhaust stroke, maybe, as i run wasted spark.
User avatar
By zoidberg
#43026
pazi88 wrote:Are you using new ignition mode? If not, try that.
I tried that but i think that is not my problem
zoidberg wrote:Another thing could be that i went for cylinder 1 exhaust stroke, maybe, as i run wasted spark.
That was wrong, cylinder 1 compression spark should be 180 away from cylinder 4 not 90... which was the case.
That is what my oscilloscope puts out when i'm rotating the distributor by hand
Image
for that i have removed the distributor from the car
Image

I am not sure if the toot pattern is too less uniform or if i have to trigger on rising or falling edge it seems that something with that trigger is messing with the ecu to a point that its not really working anymore.
User avatar
By PSIG
#43053
Your oscilloscope image indicates erratic pulse intervals, which will of course alter the calculations Speeduino does and will output a different timing on each change due to crank angle error. I would look for the source of the inconsistent pulse timing. If it's not mechanically-related, then keep looking. Every pulse should look identical in amplitude, width, and spacing to all other pulses.

My reaction is that it's responding as-expected under those conditions. A pulse 20% later will be calculated as the RPM slowing 20%, with an expected change in the predicted crank angle at that point. The next tooth is then (relatively) 20% sooner, and it thinks RPM increased 20% with a crank position to match. That's my hunch at the moment, assuming the rotational speed of the shaft was consistent. I will typically test triggering patterns and set trigger angle, etc, by cranking with the spark plugs removed so there is no speed variation from compression.
User avatar
By zoidberg
#43057
Yea I think that is the problem, I have some magnets in crooked which causes the pulses to vary in length. I switched to much smaller square magnets in another holder, I hope that works better
User avatar
By zoidberg
#43286
Oooh that is so frustrating... I changed the trigger layout to 18-1 and it doesn't work either, the jitter is less severe only like 8 degrees on the crank, but as soon as I step on the gas the engine spits and stutters. And then there is the leaning out problem where the mixture will stay good but then leans out. I'm not sure anymore what to do. Lastly it started so lose sync once every rotation. I think I will do something else to not get too frustrated.

I fixed the timing problem, it has no jitter now. […]

New 202005 firmware

is it possible there's something particular in you[…]

Yes although a simple trigger for fuel only will s[…]

Startup Jaguar V12

Pleased you have sorted the issue buddy. Give a th[…]

Still can't find what you're looking for?