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Hello, I have a supercharged Honda B16B engine with ID725 injectors. Every time I start from cold I get a misfire. Have to apply thottle for engine not to stall for about a minute then its OK. Could it be that the plugs are getting soaked due the the largef injectors? I tried to reduce cranking fuel trim but problem persisted. Using Hondata S300

What spark plugs heat range are you running?

9. Stock plugs are 7

Can you post a datalog?

the log will help but try with hotter spark plugs, that could be the problem.

Thought about going with hotter plugs. But don't think that that's the main problem. Datalog files attached.

Attached Files

This is a data log of the car running on idle and suddenly stalling

Attached Files

well, that last data log shows that it goes too rich and the RPMs drop (due to the misfire). It is consistent with plugs fouling. Any way to decrease the amount of fuel you are delivering to avoid fouling the plug if you aren't going to try hotter plugs?

Since the problem occurs when cold, perhaps your compensations for cold is too much. Try targeting .90 - .95 Lambda at idle to avoid fouling plugs.

Have you looked at the IAC when stalling? It looks like it opens up (MAP increases) to allow more air, and you then provide more (too much) fuel.

From what I am seeing there is not much of an option to decrease fuel. I removed the IACV and cleaned it also. I think it's time to replace spark plugs. Print screens attached.

Attached Files

When you say there isn't much option to reduce fuel, does that mean you tried it and it stalled (too lean) ? You can reduce your 20C open loop low load compensation.

Since it looks like overall too much fuel in low-load and idle conditions -- I have to ask -- Have you correctly configured the Hondata S300 for the ID725 injectors?

I don't know how you do it for Hondata, but many OEM ECUs need the injectors flow rates correctly specified so all the fuel tables, compensations etc will work correctly.

I didn't touch the fuel table since when it stops misfiring it works fine with correct AFR. Yes injector are configured including dead times. Main problem is only start up when cold. I will reduce the 20C compensation as well

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