Engine misfire ...

[eight-six]

Guys,

Jut trying to get as big a picture as possible as to what could be wrong with my car.

The car is running dual Carbs, still utilises the stock ECU etc for ignition. It’s all set up and starts and runs and goes well some of the time. But ignore that for the time being.

I have started to suffer some random misfire which is almost like the car is hitting some sort of rev limit. Only happens in 3rd / 4th onwards at high RPMS – can be anything from 5k onwards.

I am trying to work out why. I have ruled the carbs out for the time being. They are properly set up so no issues there.

Main suspect at the moment is the ignition system. Everything is good. Except the igniter which wasn’t testing to the specifications listed in the Toyota workshop manual. So I have replaced that.

Can anyone tell me … would a dead igniter potentially cause this sort of issue? The fault is intermittent which usually suggests something electrical.

On another note, if the O2 sensor detected rich running would the ECU try and advance the timing to lean out the mixture? The O2 sensor is hooked up (just disconnected it now for testing) but I am just wondering if the ECU is trying to advance the timing at higher RPM which is causing the miss as its throwing the timing right out.

The O2 sensor is the only sensor that is still hooked up to the ECU which could adjust the running, MAP and TPS are disconnected.