kris

I got 89.9% duty this weekend with a downpipe,drop in k&n and power fc running anywhere from .79-.82 boost. This seems kinda high what are you guys getting?

Tim Benton

iTrader: (1)

If your running the base maps, then they are set for intake, DP, and cat-back so it would tend to run rich in your circumstances as it thinks your flowing more air than your really are. You could probably take some fuel out at WOT, start off with small amounts while watching your O2 sensor. Don't go below .88 or .9 on the stock sensor to be on the safe side.

Tim Benton

thejersey7

Well my duty cycle is at 98.6% @ 16psi (.98) which is very dangerous for the injectors. So im bumping the primarys to 850cc and running a high flow pump, Im running a Power FC in my car so retuning the computer will be fun. Definitly try what Tim said over 80-85% you can risk hurting an injector

KZ1

that is high, I am running base maps and I get just 90 running .92,.93 boost

kris

What else could cause high duty cycles? Maybe a fuel pump getting weak? Im gonna change my fuel filter this weekend.

KZ1

what are your intake temps? water temps? fuel temps? that could come into play.

CYM GIRL

I'm hitting about 92-94% duty cycle at 12.5psi. I will definitely upgrade my injectors very soon, I will send them out within 2 weeks.

thejersey7

92-94% is very high for 12psi that sounds like you have something else wrong better not jump on new injectors yet

ZoomZoom

iTrader: (2)

Most of the time I hit 85-90% on .9 boost setting. Looks like I hit an all time high tonight in very cold weather of 93% @.91 peak boost. Stock Pump and Injectors. Also Base Map. with DP,MP, Intake,intercooler, Cat back, PFC.

kris

Ok, i changed my fuel filter, who wants to fly to japan to kick whoevers *** put the filter where its at? And wtf with the little chineese clamps insted of worm drives on the lines ....sheesh

Red Rotary Rocket

Kris...AMEN! There has never, EVER been a maintainance job I have hated more than changing the fuel filter....each time I do it, I swear that next time I'll just pay someone to change it for me...then by the time I need to change it again, I forget and do it myself. I never curse more than I do when changing the fuel filter. One of these days, I'm going to write a nasty letter to Mazda, berating them for that stupid design

7-sins

Kris, did changing the fuel filter fix things?

I am getting a 94% at 10 psi, not too good.

CYM GIRL

It's actually 13psi that I hit 92-94% duty cycle. I think it's because a have so many mods and the injectors needs to be sent out and upgraded. I seriously don't think anything is wrong with my car. I pretty much have every bolt on product available for my car. I had my friend take out my injectors today and I will see how everything turns out when I get them back in a week .

ZoomZoom

iTrader: (2)

This is an old thread but I figured I would mention that you should start with the fuel pump upgrade before you go to bigger injectors if you havnt already done so. The stock fuel pump has a hard time keeping up the pressure just when you need it the most.

maxcooper

The ECU knows absolutely nothing about fuel pressure, so it will not do any sort of correction for a weak pump or dirty fuel filter. Rich maps, cold temps, high boost, high revs, are the only things that drive what injector duty cycle you hit.

You could have a failed intake temp sensor, at which point the PFC should default to using the coldest correction factor, which would give the highest duty cycle for safety.

My AVC-R sometimes gets a false spike in the injector duty cycle reading, which gives erroneously high peaks. I don't know if the PowerFC suffers the same problem; I don't think so, but it might be worth investigating. Have someone ride shotgun and watch the values as you rev out. If there is a weird spike, that might just be a false reading (or screwy maps). You might be able to spot it on the graph mode, running solo.

It is a good idea to ensure that your fuel filter is clean and the fuel pump is healthy, but those items cannot have any effect on the duty cycle you hit. Oh wait, I just thought of one remotely possible way -- if the PowerFC adjusts duty cycle for fuel temps, you might have really hot fuel from a dirty filter or bad pump. But that is a long shot -- don't expect a new filter to change your duty cycle.

-Max

rx7_lover

hehe... im actually getting too low duty cycle (about 55%) on stock injectors, pump w/ 10 psi.

a weak fuel pump can cause this? it seems im running pretty rich.

maxcooper

The condition or quality of your fuel pump cannot affect your injector duty cycles in any significant way. Changing fuel pumps will not change your duty cycle. Search the internet for "speed density fuel injection" to see how your fuel injection system works, and why a fuel pump will have zero effect on injector duty cycle.

Here's a page that defines the basic terms and operating principles without getting too technical:
http://www.affordable-efi.com/Injection%20Types.htm

55% is pretty low, but might be correct from a mixture standpoint if you haven't opened up the intake or exhaust too much, and/or if your intake temps are high from using the stock IC and/or an open intake element. Be sure that you you are reporting peak duty cycle after running the car to redline under boost in a high gear (3rd or higher, to be sure you hit maximum boost).

-Max

rx7_lover

Max, thanks for your advise.

do you think you can figure out what's wrong with my values? (i posted some questions in a thread "off values? help")