[LATECH]

Saw the paragraph in the megasquirt article

The code can cope with any tooth #1 angle. However ,during cranking,the engine speed varies up and down greatly as the engine rotates. It is desireable to place the missing tooth such that it passes the sensorwhen the engine speed is somewhat stable or it may be impossible for the ECU to "see" the missing tooth. The OEMs have found that certain #1 tooth angles work well and it is worth following there lead.

That paragraph right there tells me that rotational velocity of the crankshaft WILL affect tooth count /pulses on this system.

Maybe the trouble is going on at higher RPM because of a belt or a balancer causing a velocity change in the crank due to mechanical reasons you cant see

[LATECH]

Maybe the sensor bracket is not real stable.Maybe it is vibrating which can mess up a signal

[FMile Pontiacs]

Originally Posted by LATECH

Maybe the sensor bracket is not real stable.Maybe it is vibrating which can mess up a signal

I appreciate your input. I have tried 2 different balancers on the engine. I have also ran it without belts to try and rule out those possibilities. Neither made the problem go away. As for the sensor bracket, anything is possible, but it is a sturdy piece. It is a billet aluminum unit I purchased from Innovators West. I sure can't move it by hand. I haven't gotten to work on it today. It is some better with last nights work and I am kinda skiddish of free revving in the garage anymore. I may do some testing and tuning at the track this weekend and play with the filters some. Also may try the effects of rising edge and falling edge changes.

Something else I was looking into was a 36-2 wheel configuration. I seen where it may help the ecu differentiate the actual missing tooth are from the phantom ones it picks up. Simple enough to cut a tooth off if needed. What do you all think? I am interested on input. If filter works I probably wouldn't mess with it.

[FMile Pontiacs]

I feel though I have made some progress. Last time added the resistor plugs and went to a known clean 5 volt power for the crank sensor. It helped a bunch but still had some sync loss. Tonight while researching some I seen where sometimes as low as a .015 air gap at the crank sensor is successful. I set my air gap to .015 at the tightest area on the trigger wheel then straightened out the wiring some and test fired it. As usual it sounded great but it did record a couple of sync losses at startup. The manual says this is normal and okay. I let it warm up to temp and I was able to rev the engine very well. Accidentally hit the rev limit once. It did lose sync at that point but I believe it was due to hitting the limiter. Hopefully track time this weekend will prove successful.

[Kevspontiacs@aol.com]

Good to hear you’re gaining on it

[FMile Pontiacs]

Also ran very consistent. Out of 7 eighth mile passes it ran 3 6.07's, a 6.08 a 6.12, a 6.06 and the last pass was a test pass. I have a question about. On all of my passes I had it set to fixed timing. Honestly, I forgot to put it back on the table after verifying timing. It ran great on fixed timing but on the table it broke up again. Any clue as to why this happened? At least it is in race shape again.