I have a EM4-f. I have what i can only describe as a spark drop.
A picture is worth a thousand words.
so here is what is happening.

Blue line much older dyno.
Red line new dyno.
The blue line is actual the Red line is microsoft paint.
Everything is the same.
I have tried everything. New plugs, new wires, New coil pack, Added timing removed timeing, checked and double checked magnet synchronization.
Removed MSD DIS-2.
Air fuel is good at 12.8 steady.
I have gone back to the dyno 4 times now, and this is becoming very expensive!
There are no RPM error codes.
It looks like a knock sensor is turned on.
However there is no knock sensor.
This is a TPS only system. So there is no MAP sensor problem.
All parameters are normal.
This is a naturally aspirated Honda engine.
Any ideas?

Dave,
What is the intake runner length to the valve?
We think it is not the spark breaking up or hall sensor problem, because usually these problem make the graph drop off a lot more.
Would like to see the run file with less smoothing too.
Send us the run file if you can.

racetech1@telus.net
Thanks,
Barry@sds.

If it was hall sensor then rpm pickup for the dyno would get cut in half or disappear.
Odd that it keeps revving up high too.
Try a run at half throttle maybe if you go back to the dyno and see if it still does this.
Also usually blowing out spark tends to occur at torque peak.
In the SDS the coil time gets shortened slightly at5750 and higher rpms, there is a way to keep the coil time long all the way to 8000+, phone or email for info.
-Barry@sds

thanks barry.
the intake runner length is aprox. 7 to 8 inches, from butterfly to
intake valve. They are TWM individual throttle bodies.
I did take a picture of the o-scope and a video.
I will get different dyno runs tomorrow.
From what I could tell the hall sensor signal looked clean.
But the signal from h-4 and h-6 looked weird.

Picture




Link to crappy video. sorry about picute quality.

http://s210.photobucket.com/albums/bb25/no2psi/?action=view¤t=0225081904.flv

Sorry try this link, I dont know how to go back and edit.

http://s210.photobucket.com/albums/bb25/no2psi/?action=view¤t=0225081904.flv

Here is a better vid. Now using the other channel as a trigger. scale is 2v/div.

http://s210.photobucket.com/albums/bb25/no2psi/?action=view¤t=0226080649.flv

Barry here it is without the image below the ground line.
I grounded one probe, same basic shape.


http://s210.photobucket.com/albums/bb25/no2psi/?action=view¤t=0226081259.flv

try this link.

http://s210.photobucket.com/albums/bb25/no2psi/?action=view¤t=0226081259.flv

I marked the crank pulley 180 degrees from TDC and found that the timing
on cylinders 2 and 3 changes at 7300 or 7400 rpm by 8 degrees or so.
Any ideas on what would cause this?
I am will to buy just about anything at this point! ha ha
Even if I had to buy a new ecu and hall sensor and coil driver it will be cheaper than going back to the dyno again and again.

Well I replaced the Hall sensor and magnets.
And that cured it.