Hondata

Hello,

Having a strange issue with the stock FlexFuel calibration for the FK8.

I have two data logs attached. The log titled "WOT code pull" was a third gear WOT pull from 2000rpm, running 30% Ethanol with the fuel pump duty limit NOT turned on. During that pull and nearing the top end of the RPM range, the car immediately threw a CEL "fuel pressure too low" on the dash and the car was down on power. (wish instead of clearing the CEL i wrote it down) but i cleared it, so I could get back moving.

My next step was enabling the fuel pump duty limit and hysteresis percentage to 88% (stock values) and lowering the ethanol content to 25.5% to see if things would improve. This log was mostly partial throttle and cruising (see partial E25.5 AFR" log). per the logs, it looks like AFR's are choppy and not great? Feedback would be much appreciated as I try to figure this out.

Thanks

Almost forgot to mention, this mixture is with 93 octane pump gas

You running out of fuel. Everything else is a symptom. If you look at the wot datalog you reach 100% at 3600 rpm and the fuel pressure drops. Once this happens the ECU will stretch the injector event until the injection and spark overlaps and it will misfire.

You need to reduce the ethanol content and/or reduce the air charge to keep the fuel pump from going to 100% Don't use the fuel pump duty limit; use the air charge limit.

Thanks for the speedy reply, i'll give it a go.

My last question would be why this could have happened with the stock FlexFuel tune? considering i'm only running E30 mixture, this "should " be okay to run, even though E40 is typically the recommendation. Would this be because of octane choice at 93? also, would it be recommended to do a compression test, or anything like that in case of damage to the engine due to the CEL? (or did it save itself by throwing the code)

I would not go over 30% ethanol. The original release noted that maximum power was at 40% ethanol, but the fuel pump struggles at that point, so I would stay closer to 25%.

I doubt you have damaged anything.

Here is one more log that is at 20% Ethanol content as opposed to 25%, with the fuel pump duty limit off per suggestion. To me, these AFR's look better, not sure if they are ideal per throttle position, RPM and conditions? I did not do a full WOT pull, just a partial to see if the pump would max in the lower RPM like in the earlier posted 30% log. Is there anything that still strikes you as trouble? or should I go for another WOT pull and see. Comparing the two logs (20% and 30%), I would say it's in a better place, but I Might check spark plug gap and see if it would make a difference. Anything else you would recommend checking before I resume troubleshooting? Again, thank you for your time and input.

Fuel pump looks ok. Because the cam is not a triangle the duty to capacity is not linear, so 90% duty is very close to the maximum fuel pump output.

I would not mess with the spark plugs. If you get misfires it is from the injection event overlapping the spark and the gap won't change anything.