Yes another stupid RPM question

curt h
Posts: 2
Joined: Thu Oct 12, 2006 2:17 am

Yes another stupid RPM question

Postby curt h » Thu Oct 12, 2006 3:05 am

I'm a long time DL90 user. It's been disconnected for a couple of years and if I recall correctly I quit using it due to bad RPM readings and no time to figure it out. At one time with this configuration it used to work fine.

Just did some ignition upgrades (Hi Fire box and coil) to the race truck and reconnected the DL90 and am getting bad RPM readings. It randomly jumps from about where it should be all the way to 6K bouncing all over the place in large jumps with no pattern I can recognize.

Troubleshooting
I moved the HT lead pickup further away from the coil.
I tried using the tach output from the Crane HI6 box which drives the autometer tach fine but no reading. Not sure if the spk grnd is still used, tried both ways.
I checked the tach wire voltage it it was 2.5 volts so I know I'm not feeding 12v
Tried chassis ground, then motor ground, then no ground.
Tried 4" of foil on the HT lead, no joy.
Tried a sing;e plug wire and it got better but still inconsistant.
Out of ideas...

On interference
I just put in a high fire ignition box so interference is potentially a problem since it's located right under the aluminum sheetmetal dash like almost on top of it. I took the logger off the dash and held it about 18" away and same result. If it matters I'm running Magnecor KV85 EMI shielded wires due to the computer I run doesn't like interference.

I'm assuming the instructions for the DL1 on this issue are the same so I read both sets looking for ideas...Thanks, Curt

Edit...Something I just noticed, my GPS light is bouncing on and off like a modem light. Whether the GPS is connected or not...With the motor off, it's off...
DL90

curt h
Posts: 2
Joined: Thu Oct 12, 2006 2:17 am

Postby curt h » Sat Oct 14, 2006 4:32 am

I moved around a bunch of wires today. The RPM is now stable enough to use if I record it and then analize later. When using the monitor program it's still way bad. I'm thinking it's the serial cable picking up excessive noise...Curt
DL90


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