noise filter: still rpm spikes and starter kickback

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flowbench
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noise filter: still rpm spikes and starter kickback

Post by flowbench »

Hello !
I am running MS2 on a 3.0 Board in my 59 Chevy with an HEI 8 pin ignition. Now I am still fighting with starter-kickback due to rpm -spikes. I tried all kinds of noise-filtering, when setting the "skip pulses" option to "12" the spikes came down from around 30000 (!) rpm to 1000rpm during cranking, but still far away from being satisfying. My starter will come apart soon with this going on. I tried all kinds of other filters,even for kick-starting the engine and have been trying settings that I found other people here have more or less successfully used. And strange enough with the throttle cracked half way open during cranking the symptoms seem to disappear more. On the attached log that shows just cranking you can see the spike going towards 1000 rpm. The voltage drops sometimes considerably since, -maybe due to the spikes and therefor early false timing, the starter comes often to one point where it has a hard time turning the engine. Any ideas here ? I am stranded ! Thank you !!
DaveEFI
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Re: noise filter: still rpm spikes and starter kickback

Post by DaveEFI »

Your battery volts are dropping very low too. I'd start by using a max/min DVM to see if they really are going that low. If not, I'd investigate the power feeds and grounding to MS.
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billr
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Re: noise filter: still rpm spikes and starter kickback

Post by billr »

What is the cranking spark advance, and have you verified it with a strobe-light?
BigBlockMopar
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Re: noise filter: still rpm spikes and starter kickback

Post by BigBlockMopar »

Some coils can fire premature when dwell time is too long/much.
Try turning down the Dwell Battery correction to max 200% orso. That gives you a max 6ms of dwell time, instead of 12.65ms (around 400%).
Fixed my kickbacks during cold starting.
Daily driver: 1973 Dodge Dart - 360ci engine - 11.3:1cr - MS3x - ignition only. 42RH/A500 OD+LU transmission / 3.23 gears
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Re: noise filter: still rpm spikes and starter kickback

Post by whittlebeast »

Remove the plugs and kill power to the coils. Do a composite log for about 10 sec. A normal data log would also be helpful. Post the results with a MSQ and let's see what is going on.

I am looking for solid tach signal to the ECU

Steady RPM in a data log

Reasonable cranking RPM and steady battery volts supplied to the ECU

Later we will put the plugs in and do the same test. We still don't want it to fire yet. At this point we can verify the spark timing is close at the timing marks.
flowbench
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Re: noise filter: still rpm spikes and starter kickback

Post by flowbench »

Thanks everybody for the inputs !
Tonight I did two composition-logs with the plugs removed and installed. All noise-filters were turned off. Coil was disconnected. The starter now turns and works perfectly. Both logs look the same and o.k. to me....
If someone how is familiar with these kind of logs please take a look. The actual ignition timing is what the ECU commands/sees. I will check all the other things tomorrow.
Thanks so far, cheers Cornelius
flowbench
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Re: noise filter: still rpm spikes and starter kickback

Post by flowbench »

O.k., still no real improvement. I tried everything that was suggested here and in other posts: checked that actual voltage and timing is what ECU sees/commands. Shielded all the wire-harnesses around the distributor and attached the shield to battery negativ.Got me a new battery,- that solved the voltage dropping from dropping so low. Also I did a voltage drop test on the starter: 0,5 volts on the positive side while cranking, 0,o on ground. Played with "skip pulses": as higher the number as longer it takes for the first spike to occur. I reduzed voltage/dwell correction which helped a little bit. I played with all kinds and combinations of noise filtering. Interesting here: With noise filter "off", tach period "on" and tach rejection "on" the O2 sensor is not (!) working. So I disconnected the sensor including the heating from the system. No improvement. Did the same with the alternator wiring harness and the v-belt. No change. I played with the curve on "noise filter". Did too much and car didn't want to start , had backfire and smoke coming out of the intake. Question here: how sensitiv are the settings ? Will 2 usec at 500rpm make all the differnce in the world or do nothing at all ? I wasn't able to find any informations on that. The improvemnt after going through all this testing was that the rpm spikes are now only up to 3000 rpm while cranking and not over 30000 as they used to be. Now the only way to start the engine without killing the starter is: crank engine less than a second and stop before first misfire occurs. Wait a second, crank again for less than a second. Sometime it'll start then right away. If not, I'll crank a third time but then it'll always start running.That is bad compromise of course and still would love to figure out what is going on.... Anyone with any ideas ? THANKS !!!
slow_hemi6
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Re: noise filter: still rpm spikes and starter kickback

Post by slow_hemi6 »

I suspect it may be because it is rapidly switching from module (start)to est(run) then back to module then back to est. You can even see this on a successful start. I am not really sure how to fix it but this is one of the reasons (difficult starting) I got rid of hei and went to crank trigger and BIP373 years ago.
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billr
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Re: noise filter: still rpm spikes and starter kickback

Post by billr »

Does the timing light show 9 BTDC while cranking? Is it a simple light, not dial-back? Have you checked cranking spark timing on all cylinders?
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Re: noise filter: still rpm spikes and starter kickback

Post by turbo conversion »

I would try setting the cranking rpm to 300 and the skip pulse to 3, it is only a few key strokes to try.

Also I am curious, is there a reason you have noise filtering on but the time (ms) set to 0 making it not active?

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Re: noise filter: still rpm spikes and starter kickback

Post by BigBlockMopar »

What kind of coil are you running?
I've tuned down the dwell time to about 3.5-4ms while starting currently.
Which might be still a little too much 'cause mainly during hot-starts I occassionally notice a short kickback one in a while.

Could be you need to limit your dwelltime further.
Maybe you can run without any additional battery compensation dwell time. As long as the engine starts, all is well.
Daily driver: 1973 Dodge Dart - 360ci engine - 11.3:1cr - MS3x - ignition only. 42RH/A500 OD+LU transmission / 3.23 gears
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gjestico
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Re: noise filter: still rpm spikes and starter kickback

Post by gjestico »

How is your Tachin configured on the board hardware ?
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flowbench
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Re: noise filter: still rpm spikes and starter kickback

Post by flowbench »

Thanks for all replays !! Sorry for not getting back earlier due to travelling in job. Well, let me go through the inputs I received and try to answer everything: In first place I did have serious issues with my new MS2, like getting no rpm-signal at all, had all kinds of weired stuff going on, like starting was only possible with pin 6 disconnected ( that tells the ecu if engine cranks) dealed with it for a year and finally Phil Ringwood from England, thats where I bought it from took my MS 2, the distributor and coil, put it on his teststand and fixed it. I dont know what he did...and so I don't know how the tach-input is configured right now. I was using the optoisulator- circuit before.Exept the spikes the system ran perfect from that time when I got everything back from England.
Did play with the crank rpm-setting, lowered "skip puls" down to 3,- no improvement.
The coil is a brandnew external Accel dfi coil. That kind of coil did ran flawless for the last 15 years with the trusty Accel Gen 6 DFI-System I had previously on the car.
When I am back home I will again check cranking-time.
I lowered the dwell/voltage correction even more but came to a point where the engine had a hard time starting. At least the rpm spikes came down from 30k to only 3 k just with the dwell/volt correction I have done before. But I cant go further anymore here.
Any other ideas ????
Thank you !
billr
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Re: noise filter: still rpm spikes and starter kickback

Post by billr »

How old is the dizzy cap? Maybe you have cross-firing in there and simply need a new cap. That previous "pin 6" issue sound suspicious. Does pin 6 control the HEI bypass or whatever for starting? Obviously, I haven't read-up on HEI, just wondering if there is a hint there.
flowbench
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Re: noise filter: still rpm spikes and starter kickback

Post by flowbench »

All ignition components are more or less brandnew. I'll think about that "pin 6" issue again... When I am back home I will play with the voltage/dwell correction again since that helped most of it.
billr
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Re: noise filter: still rpm spikes and starter kickback

Post by billr »

Can you "hard wire" the HEI bypass, right at the dizzy/module, to confirm it is going in-and-out of bypass when it shouldn't be while cranking?
gjestico
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Re: noise filter: still rpm spikes and starter kickback

Post by gjestico »

What is "pin 6" on the module ? They are not marked with numbers. Is that pin R you are referring to ?
67 Chevelle, LSX V8 engine, EFI., cuppa 80's TPI projects....I like wires.
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