Help with spark latency

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billr
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Re: Help with spark latency

Post by billr »

I don't think you ever answered... is the "crank wheel" actually and rigidly mounted to the crank? If it is actually on a cam or dizzy you will always have a bit of slop in the cam/dizzy drive and resulting timing scatter. I see splines in the hub of that trigger wheel, even if it is mounted on the crank, is there slop in that spline-drive? Whether you are talking about 3 trigger edges or 6, it is still kind of crude. If you have any reasonable means of making a new wheel with more teeth, do that; don't waste time with a special input circuit that isn't going to gain you much. Point is, though, that if the crank trigger wheel isn't coupled directly to the crank, no amount of teeth on it will ensure stable timing.
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

It's on the crank. That is on the crank timing gear going to the cam belt. It's directly on the crank behind the belt pulley harmonic balancer. It's don't get and more rigid then that haha.

I'd like to keep the stock setup.

I'm getting 6 triggers with each cam trigger so there shouldn't be a reason I can't go coil on plug and have accuracy
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

Also if I end up making a new wheel can I keep the hall effect sensor or do I need to go vr?
dontz125
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Re: Help with spark latency

Post by dontz125 »

This is the board I was talking about:
Rising Falling Edge Trigger.jpg
Not very big, 1.4" x 1.0"

Mouser part numbers:
  • IC1: 595-NE556N
    Q1: 512-2N3904TF
    C1, C3: 594-K103K15X7RF5UH5 (x2)
    C2, C4: 594-K102K10X7RF5UH5 (x2)
    R1, R2: 71-CCF071K00GKE36 (x2)
    RN1: 268-10K-RC

If you're talking about a 36-1 wheel, a Hall sensor will still work.
QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
Coming soon: OctoMAP Sensor Module
TTR Ignition Systems
slow_hemi6
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Re: Help with spark latency

Post by slow_hemi6 »

Just a question for Don, do you think there would be issues with slew rate or actual trigger point of rising vs falling edges being different that might equate to a degree or two at higher rpm? I just know from my own scoping that it is not unusual for rising edges to have a different ramp to falling and the sharpest transition is usually the best to trigger on.
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
dontz125
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Re: Help with spark latency

Post by dontz125 »

I agree that is something to watch for, and it is entirely possible that the timing variations will render the exercise unworkable. Bear in mind the experiment being pondered is to use BOTH edges, so any efforts to use "the best (edge) to trigger on" are wasted.

That said, I would suggest that a great deal of the difference between rising and falling edges is in the 'cleanness' of one edge vs the other. If the OEM used the leading edge for timing, then it sometimes happens that the trailing edge will be indifferently machined, with a different angle, a ragged edge, or a varying width / position relative to the leading edges and even other trailing edges.

The OP says his wheel looks pretty clean, and James said his scope trace looked pretty even. It may be that the improved resolution of 6 pulses will offer less jitter than 3 pulses on the best edge. It may be that the engine is sufficiently uncaring of ignition timing that there is little performance difference between those cylinders triggered on the leading edge vs the trailing edge cyls.

The only way to know is to try it and see.
QuadraMAP Sensor Module -- PWM-to-Stepper Controller -- Dual Coil Driver
Coming soon: OctoMAP Sensor Module
TTR Ignition Systems
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

I got a update. I updated to 1.3.3 and ran it... took some time to get all the options set but I got it running.

The code I feel helped in some ways but didn't solve the problem.

Before when revved up like snapping the throttle would stumble some to and on fixed 10 degrees would jump retarded about 3 degrees and then lunge back to about 15 to 20 degrees advance like it was trying to compensate for the stumble after the throttle was released.

Now it stumbles as it did before. Maybe a little less it seems but it don't jump back advanced after stumble it goes from 10 degrees then snap the throttle to about 2 or 3 degrees retarded with a stumble then straight back to 10.

If you raise the idle slow it seems to be ok.

It does also have much less knock on the sensor window.

It seems a bit happier with the new code but still not enough.
I also as a last attempt switched to wasted cop and it seemed smoother at first but still same hesitation
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

New composite log
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

My crank wheel is cut exactly the same on rising vs trailing. The cut comes in with a filet radius much like how a crank is cut at the bearing journal. Rounded up.
The cuts are all equal all are 60 degrees of the wheel
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

I also have a question. When I used a timing light to get my angle #1 I got 309. Would a few degrees possibly give me this issue? Could I be off causing it to jump like it's been? If yes then I'm getting a better timing light and ditching this cheap one I got
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

Another thing is my cam sensor is a half moon and I'm using it as a rising trigger.
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

I ordered the parts for the rising falling trigger and will build as soon as it arrives. Thanks
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

I got to ask would trigger return be useful?
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

Here's some text about the stock system
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

Dontz125 I pm ' ed you
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

You were right sir. I turned down my tps threshold to 80 and it revs nicer. It was at 200 for some reason and the car hated that.

I got a lot more tuning now since I switched stuff around...

I'm also planning to have my crank trigger made with 36 - 1 teeth.
billr
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Re: Help with spark latency

Post by billr »

Help me learn some here... did the TPS filtering reduce the spark scatter that was the original problem in this thread??? The last I remember, the rising-falling scheme to make that crank wheel "6-tooth" didn't help much/any, and you were still wondering why you had some misfiring with MS and not the OEM ECU; is that misfiring what TPS filtering helped, not the spark scatter? Is the spark scatter still with you?
thecrew2999
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Re: Help with spark latency

Post by thecrew2999 »

Yes it is. Factory does the same thing when I pull the spout connector it sets 10 degrees fixed so I put the timing light on and revved it. It shown a jump advance the corrected. That's stock and it was fine.

Once I fixed my threshold it was much better. Still advanced like factory and before but it didn't stumble
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