Engine misfire ...

[eight-six]

Quote:Ok - with the CEL permanently lit, the ECU is not providing any ignition advance and triggers the spark with the base advance only. So by rotating the distributor as you described, you set a lot more base advance, causing the spark to be triggered at a static angle of, for example, 32deg BTDC. This isn't a best possible solution but works reasonably well, especially on race cars which see mostly full-throttle acceleration. I know that several AE86 rally cars in Finland run this way.

Yeah, it’s obviously not ideal for road use as it means the engine is quite flat at anything other than full throttle and long hills are tedious, but then I only use the car for track days and drifting so not massively fussed abut how it runs on the road.

Quote:When the CEL is not lit, the ECU either uses the normal advance map or the simple overrun map - depending on whether the switch inside the TPS is open or closed. The overrun map is pretty much a static ~30deg advance when above 2000rpm. The normal map is probably the best solution but requires that the ECU can detect all sensors and that the idle switch is always open. The ECU does set error code 11 but doesn't go into limp mode (not a fatal error, so CEL won't get lit) so it'll provide a variable advance throughout the rev range.

I suspect that’s why all the sensors were disconnected then as it was easier to unplug all sensors and lock the timing out than try and connect up the stock TPS etc. Potentially though would the fixed timing route result in more peak power over the variable timing option – but the variable timing option resulting in better driveability?

Quote:JMR_AW11's articles on the 4A-GE ECU secrets were quite helpful in making the ECU play nicely along with carbs but unfortunately it seems that they're no longer online..

I will check the IMOC as I think that some of his stuff is saved to the forum.

Quote:Actually, you're right - the idle mixture pot (and thus apparently also the O2 sensor as they use the same ECU pin) has effect when below 3600rpm and partial throttle (light to medium engine load).

Ahhh now as the ECU isn’t taking a reading from the TPS that could be further confusing it? But then it would be getting an RPM signal.

I suspect the issue was the result of the igniter as another issues I have had previously (revs hanging occasionally – but not because of the throttle / bad starting and occasionally lumpy idle “seem” to have gone away)

As a further test I will connect up the O2 sensor and take it for another run to see if it recreates the problem so I know for sure.

Car is going to be on the rollers this Saturday so it will be interesting to see what sort of power its producing.