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12.8-13.4 AFR at idle ok?

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I can't seem to get the car to idle much leaner than 12.8-13.4 AFR at idle (it fluctuates due to the size of the injector and the small displacement motor they're on) . Its a 4G63 standard displacement with ID2000's on pump gas at the moment. I was considering lowering the base fuel pressure in hopes of getting it in the high 13's, but i'm not sure if its needed? It idles reasonably at this AFR. However, I remember reading somewhere (it might also be in one of the courses if memory serves me) that you don't want to idle richer than 12.5:1 as you can start to wash the bores down with fuel. Being that I'm close to that when the car is fully warmed up, do you think this would be a problem?

It's a bit on the rich side with Lambda 0.87. Unless you have an aggressive cam there would not be a reason to idle richer than Lambda 1. For sure not ideal for lubrication, but not sure if it is already rich enough to cause an issue in your application.

Have you tried different idle speeds?

What are the real opening times you are seeing on your injectors? They are a bit big for pump gas. Are you running sequential injection?

I'm currently at 1100 rpm for my idle. I could bump it up to 1200 to see. Its a fully built head with fairly aggressive cams, but I do agree that it's a little on the rich side.

The car is sequential injection. I'll have to see what the opening times are actually. I know they don't like much lower than 1ms and I'm basically requesting 1ms pulse width at the moment.

I don't like to idle richer than ab out 0.85 for extended periods, not due to bore washing but more to do with the risk of fouling plugs. While bore washing can happen, it's usually a result of a more serious issue where the injector is leaking or the engine is run for long periods with sustained rich mixtures. You are probably getting towards the useful minimum of the ID2000 on that engine on pump gas but just make sure your settings for minimum pulse width (if your ECU has this setting) and dead time are set correctly.

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