How to tell if you are out of injector

[ES1]

Is duty cycle only read on direct scan or is there another way to tell?

Thanks
ES

 

[peterkin]

yeah, when you go lean on top end no matter how much you turn up the fuel pressure. when the duty cycle is waaaaaaaaay over 100%. your problem could also be your fuel pump not being able to keep up. i believe that's what my problem is now. what injectors, and what kind of times are you running now?

 

[bruce]

Originally posted by ES1
Is duty cycle only read on direct scan or is there another way to tell?

In short just about all the chips that I've seen for injectors smaller then 55s are set to run static.

If you want to see you DC, you can use a dwell meter, to get an idea of where you are. They're generally an analog guage so will suffer some from over shooting, but a couple sec at WOT should peg the guage.

There are several issues that run parrallel about WOT and injectors. MAF Dropout, and injector sizing are BOTH stumbling blocks.

 

[ES1]

Why I asked, I see where peterkin & ijames are say they were out of injector @ mid 12s on the 40s. My 102 mhp on these injectors show 0 knock and 02s in the high 700s @ 18.5psi with 44 line off FP.
Is this a case where each car and injectors are different?

 

[boostcreep]

Just be careful..at anything over 90% DC, you can get to where the injector can *hang* not fully opened or closed.

Nick

 

[ijames]

Originally posted by ES1
Why I asked, I see where peterkin & ijames are say they were out of injector @ mid 12s on the 40s. My 102 mhp on these injectors show 0 knock and 02s in the high 700s @ 18.5psi with 44 line off FP.
Is this a case where each car and injectors are different?

Sounds to me like you have enough injector for your current airflow. The test is see how far you can turn the boost up (with sufficient octane, of course) before you can't keep the O2's up where you want them. A practical limit on base fuel pressure is about 50 psi vac hose off, engine idling, since the delivered volume falls with increasing pressure and that's where most pumps begin to fall off (well, 50 psi base + 20-25 psi boost for 70-75 total at the pump). In my view you are out of injector when you can flow more air than you can supply fuel to match. Personally, I think that it is safer to have the limit be airflow, not fuel, so you shold be "out of turbo" instead of "out of injector", but either way you have to be intelligent about tuning so when one is maxed out the other isn't turned up too far.

Octane also matters because you generally want to run a little leaner with race gas than pump gas.

 

[LIVE4MPH]

Jason Hall went 11.2 @ 121 with those injectors. I think you just need more fuel in the chip. Good luck

 

[peterkin]

i think my fuel pump is on the fritz, as i stated above. i've seen people run 11's on my injectors.

over the winter i'll change the pump, and the filter.

 

[REDS HOT AIR]

Originally posted by peterkin
i think my fuel pump is on the fritz, as i stated above. i've seen people run 11's on my injectors.

over the winter i'll change the pump, and the filter.

why you thinking pump??

I can tell you my pump is done went to bigger injectors and it leans out earlier than it did with 50's

it's falling over about 1000 ft mark with 58# base fuel

went thru coming out of it at 125 ...thats stock fuel line and single 340 pump.

these cars suck out the hole at 58# fuel pressure..1.81 60 ft but 10.97 et

102 mph 1/8 pump should be ok till 120 or so trap

 

[blackbuick87]

Time to update the sig isnt it, Red?

 

[REDS HOT AIR]

Originally posted by blackbuick87
Time to update the sig isnt it, Red?

not happy with way its running so i leave all my old stuff on till i get fuel system strait and go back to track..wont be long