Trigger error?

[art leong]

I put a new trigger wheel on. Same size as the old one 20 tooth. I went to a race and the car lacked power. Checked everything I could. It idles fine.

The only 2 abnormalities were trigger errors. I started with 8 (probably from the burnout) Went from 8 to 21 during the run another 20 stopping. In the past I might see 1 or 2 trigger errors in a weekend. I'm using the same pickup (magnetic reluctor) in the same bracket.

The other was I run 2 wide bands AFR sensors. One is in the header collector about 8" from the end. It does not read much till you get over 4500 rpms. The other in in the header pipe from #4 cylinder about 12" from the head. This one I used basicilly to check AFR at lower rpms. When I looked at the last datalogged run. It showed a pretty much higher AFR than the one in the collector. On previous runs it would show 13.5 or so about the same as the other one. But on the last run it was higher (about 14.5).

I'm wondering if the trigger errors could have caused this?

One thing I did change was the air gap for the reluctor It was set at .050" with the new wheel it was set at .030" I did not change filter or arming threshold numbers

They are,

filtering level 1,

Arming threshold 0=.02, 1000=.09, 2000=.06, 3000=.06, 4000=2.3, 5000=3.9, 6000=5.6, 7000=7.3

[Simon]

Trigger errors will normally be accompanied by a miss fire.

The material of the wheel can effect the signal strength as does the sensor gap. You will need to recheck the arming voltages and the timing offset.

[art leong]

My arming voltages are high up to 22 volts ac at 6000. At idle 900 rpms it's at 14 volts ac. On the voltage threshold I can only set them to 7 volts.

The sensor I have worked before I changed trigger wheels. Same diameter and same tooth count. And upgraded the firmware.

One thing I've noticed is that the timing seems to jump around even when calibrating

I have a mark at 20 degrees and the reference timing is at 20

[Simon]

At crank you might see a bit of movement in the timing but once engine fires it should be stable.

The critical bit is getting rid of the trigger errors.

What do you have for a cam sync? One thing to avoid is having the cam sync happening on top of a tooth on the crank. It is best to have the sync tooth between crank teeth.

[art leong]

Thanks Simon. That seems to have been the problem. It was jumping about 18 degrees and I have a 20 tooth wheel (18 degrees).

It went up the track like it was significantly retarded. I moved the trigger wheel a few degrees. And It seems much more stable.

The help on here has been outstanding. I don't have anyone in my area that works on these ECU's. So it's been a learning experience.

I hope others on here been helped as much as I have.

My crank sensor voltage and threshold. Is my next question