Hey guys,


My car has been seeing some hard misfires lately. They feel almost as hard as an overboost cut, but I've data logged and that is not what is happening. Instead, when I get the misfires, the data logs freeze everything. RPM freezes, AFR, PW... very odd. Attached is the log. Any idea on what's going on? When I run <10 PSI, the car runs OK... once I up to 12, it starts to misfire at high boost. I'm going to go bald ripping my hair out with this issue. Log attached with lots of spacebar usage when it happens. The logs have RPM drops at record 376 and 1032. Channels stop moving at records 1393 - 1406. Any ideas on what the cause or what I could do to fix this? Thanks.

 

I did see the RPM drop to zero once, which COULD be a sign of a flaky CAS. This seems more like a noise issue, however. Any chance it could be spark blowout? Misfires can cause a bit of noise; try gapping your plugs tighter.

 

Thanks for the input Matt. I've been afraid of a bad CAS sensor. Would a bad CAS be more RPM dependent and not so much load dependent?

I'll try re-gapping the plugs. This has been a problem since I switched to COPs. I've run BKR7E's and BKR7E-ix iridiums, both gapped at 0.035". Maybe I'll reduce that to 030 and see if it helps any.

 

I would not expect a bad CAS to be load dependent.

Toyota COPs are, at best, an incremental upgrade over stock. You might want to go with an ignition with a bit more firepower.

 

Matt --

Thanks for the help. I gapped the plugs down, and the issue has gone away. I upped the dwell from 2.5 to 2.9ms based on this article https://www.miataturbo.net/megasquirt-18/dwell-observations-toyota-cop-44131/ and finalized gap at 030 and the car runs smoothly.

Rave reviews on the Toyota COPs led me to believe they had a good bit more juice than stock. What would you recommend for a high power ignition system?

 

Probably the badass one they sell that I don't know how to wire.

 

They need switched 12V, 2 power grounds, 1 logic ground, and trigger. I think you could handle that.