Got a miss going on. It's intermittent. When the miss occurs, my wb reads full lean. I'd normally think secondary ignition, however when this miss occurs, the tach will drop ~500 rpm for an instant concurrently with the miss. It typically occurs while cruising between indicated 3k-3.4k rpm (but that may be because that's where I cruise at around town). But once I noticed it happening while decelerating in gear with my foot off the gas.

What would cause an ignition miss AND a simultaneous drop in RPM reading on the tach? CAS related? I do have a butt connection where the MSD box used to intercept the signal.

I have extra plugs & wires. Could throw them in to see what happens, but I'm not betting on secondary ignition because of the tach phenomenon.

 

Can you see anything on a datalog? If the CAS is dropping out due to those two butt connectors in there giving out then we might be able to see it there...

Is it rare, or somewhat consistent?

 

It started as occasional, but seems to be getting more frequent. I see these little spikes of 0 injector activity in my datalog. I assume it's related.

 

My money is on bad earths

 

It's the factory harness so that normally shouldn't be a problem... though I think the grounds were vampire tapped for the wideband which can damage them.

Ben-- email me your full datalogs so I can take a closer look.

 

I second that, either a poor ground or poor power

 

datalog for anyone else interested.

 

problem seems to be cured by swapping in a different ignitor.

 

i had my money on ignitor as well it sends out RPM signal maybe your dwell time is cooking it slowly and then it starts to miss. just a theory

 

Thinking about it I have the same issue, and I assumed it was bad leads (a different set solved it for a time).

Think I'll try swopping the coils for a spare set I have and see what happens.