Thread: AFR looks too high
09-01-2009, 06:27 PM #1
AFR looks too high
I ran my ski today with the E1 wheel and new intercooler. Numbers were 79.7 with a full tank and rpms were between 8400-8500. Had fuel pressure at 64 psi. AFR moved around alot. It was between 12.5 and 13.5 at wot. Sometimes it said 0??? Does this mean I want to turn it up to 66 -67? Why is the reading 0 sometimes at wot? Log is attached.
09-01-2009, 07:50 PM #2
You have an interesting log, did you notice that fuel injector duty cycle gets way over 100% on your full throttle?!!? I guess that explains the lean spots showing in your lambda at full throttle... i guess you would need to increase you fuel pressure or do something with your fuel map
09-01-2009, 07:57 PM #3
Ya I noticed that it got way high. I'm going to set the fuel pressure at 67 psi and see what happens. I remember others had the fuel injectors going over 100% so I want to see what they have to say. I'm waiting on Nils to give me a call back.
09-01-2009, 07:59 PM #4
It's real easy to make minor changes in the pressure (like 1 psi at a time). I use a glycerin filled Edelbrock fuel pressure gauge on the line at the rail using R&D's fuel pressure fitting thing a ma job. A spark plug socket fits the lock nut and then you just need a hex wrench to adjust pressure on the regulator. Should be able to be on the water and easily make these changes.
BTW, I have ran as high as 70psi with the stock injectors and still was just a little lean at WOT. I wouldn't jump right to that pressure though.
09-01-2009, 08:02 PM #5
Biz, what do you think about the the fuel injectors being waaaaaayyyyyy high at WOT? Is that a problem? You are right that changing the fuel pressure is easy.
09-02-2009, 08:33 PM #6
I would say that if duty cycle is high, WOT is often needed, and the logs indicate the Lambda needs improvement at WOT you need to look at higher flow injectors. Lambda can can make a big difference in engine temp among many other things...
09-02-2009, 08:37 PM #7
Injectors are definitely in the plans but I think nils said they don't have a map for the different injectors yet.
09-02-2009, 08:52 PM #8
09-02-2009, 09:09 PM #9
You do not need a new map. You only need to do a global trim to your current fuel map. You need to reduce injection time to compensate for higher flow volume. If your fuel curve was right on your current map, then it will be right with higher flow injectors... you just need to perform an overall flow correction to get to your desired afr. A simple rule of thumb.... if you install injectors that flow 20% more.... then trim down your injection time by 75% of that (20% X 0.75 = 15%, which is safe), go test and perform fine tuning of your global trim until you get the desired AFR.
09-03-2009, 07:03 AM #10
Probably going to hold off on new injectors till next year. I have a month or two of riding left for the season. I'll enjoy my ski for a while till its done for the season.
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