He might not...according to the lines

Duty cycle too high... I had Eugene tune my car too, and we never even bothered with e85 because I was already at 80% on pump gas!

I have 1050x and Walbro 485

Is your FPR Working? 442 WHP should not be needing 90% duty cycle. Hopefully you figure that out, but it sounds like maybe your fuel pressure is not raising at a 1:1 ratio.

I spoke with Eugene and he said:

It was checked. The duty cycle is around low 80s at 6200 RPM on e75. And with very reasonable fuel target. The increase in duty was also linear.

Fuel pressure isn’t something the ecu logs. Are you saying Eugene checked that your fuel pressure and FPR were working during the pull? I had to setup my phone to video the pressure gauge for him. And during the one 2nd gear pull I did, it looked like the rate was not rising 1:1 in my case, which might be my issue. Going to have it looked at on Monday.


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I didn't start maxing out my 1050x's and walbro 485 until I got into the 600whp range on e85.

He said the gauge in the engine bay is what was looked at, it was observed at during the pull by someone else other than him.

You may have been running out of fuel vs maxing out injectors :ugh2:
Bigger pump, lines, etc...gotta have plenty fuel available :hello:

He's got the walbro 525 and CJM S1.E rfs

This makes me wonder if ecutek is not reporting or receiving correct data. Bug? This makes no sense. If we saw AFRs drop below target, that would help with identifying such an issue. Something just not adding up.


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That’s a big pump :eek:
I know you gotta run it rich with the ethanol vs gasoline at wot :ugh2:

I had to go to CJM twin pump system when I got over 600whp (walbro 485/525).

:wtf2::icon14::wtf2:

Imagine trying to run Top-Fuel with a 1:1 AFR :icon14:

The pistons would probably melt on start up. :rofl2:

The plugs melt at half track, and from that point on. It's just a diesel. :icon14:

So I decided to take my car to SOHO Motorsports to figure out why my duty cycle was 80-90% on pump. Fuel pressure was about 41 psi at idle. They set it to 50 from what I hear, I think this what they normally set it at?? and re-tuned the car for pump. Duty cycle is now 60 or so, or in the 60’s, not sure. I don’t have logs, this was just a late night conversation at the shop after being awake more than 30 hrs so I wasn’t all there :). But we went from having a conversation when I first showed up very much like you had, talking about lowering rev limit, getting 1300’s, to there now being no issue with moving ahead with e85. Raising fuel pressure alone this amount does not account for this dramatic of a drop in duty cycle according to what I’ve read. In fact when I was still working with Eugene, I went to the trouble to try and figure out what it would take to go e85 based on my high duty cycle, and came up with it would take 64.5 psi at idle. If raising fuel pressure to 50 alone was a fix for all my fuel troubles, I think Eugene would have simply asked me to raise fuel pressure and we would have done some pulls. So, I think there may be something in either the tune or in how duty cycle is being calculated that’s not quite right. And BTW, this was in the 550 WHP and 425 TQ range.