why am i gettting such high inj duty cycles?
09-30-02, 01:25 PM
#1
Eats, Sleeps, Dreams Rotary
Thread Starter
why am i gettting such high inj duty cycles?
my mods are full exhaust, intake, power FC, and now the M2 medium ic.
On sautrday i installed the m2 med ic. i then proceeded to try it out. The weather is much cooler now keep in mind. Anyways when my power fc recorded a peak hold boost of .89 i also saw a peak of 98.9% inj duty.
I then decided to lower boost and make another run and this time also pay closer attention as to where my injector duty cylces are so high along the rpm range. On this run the power FC recorded a peak of .84 boost but still a high inj duty of 94.5% which occurrs above 6800 rpm's. My question is why am i running such high inj duty cycles if my car is tuned to a 11.2 afr? This tuning was done before the intercooler. I mean how could an ic make you run more rich? The only conclusion you can make about the high duty cycles are that i am rich as hell...but i am not @ 11.2.
My understanding is that the stock injectors are sufficient up to 12 - 12.5 psi of boost and that you only need to upgrade them if running more boost....Someone please enlighten me!
Thanks!
matt
On sautrday i installed the m2 med ic. i then proceeded to try it out. The weather is much cooler now keep in mind. Anyways when my power fc recorded a peak hold boost of .89 i also saw a peak of 98.9% inj duty.
I then decided to lower boost and make another run and this time also pay closer attention as to where my injector duty cylces are so high along the rpm range. On this run the power FC recorded a peak of .84 boost but still a high inj duty of 94.5% which occurrs above 6800 rpm's. My question is why am i running such high inj duty cycles if my car is tuned to a 11.2 afr? This tuning was done before the intercooler. I mean how could an ic make you run more rich? The only conclusion you can make about the high duty cycles are that i am rich as hell...but i am not @ 11.2.
My understanding is that the stock injectors are sufficient up to 12 - 12.5 psi of boost and that you only need to upgrade them if running more boost....Someone please enlighten me!
Thanks!
matt
09-30-02, 01:32 PM
#3
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the stock ecu maxes out the injectors too, you need to rewideband it and see where you are
mike
mike
09-30-02, 01:33 PM
#4
Eats, Sleeps, Dreams Rotary
Thread Starter
so i need to upgrade the injectors already when i am still at 12psi of boost?
I have read you only need to do it if you are running more boost
I have read you only need to do it if you are running more boost
09-30-02, 01:35 PM
#5
Eats, Sleeps, Dreams Rotary
Thread Starter
Originally posted by j9fd3s
the stock ecu maxes out the injectors too, you need to rewideband it and see where you are
mike
the stock ecu maxes out the injectors too, you need to rewideband it and see where you are
mike
09-30-02, 02:14 PM
#7
Eats, Sleeps, Dreams Rotary
Thread Starter
Originally posted by Mahjik
No, you need to tune your ECU for your current mods..
No, you need to tune your ECU for your current mods..
Anyone know how much a stock pair of secondary injctors will cost used?
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09-30-02, 02:24 PM
#8
Originally posted by matty
Well it seems i am maxed out on fuel....
Anyone know how much a stock pair of secondary injctors will cost used?
Well it seems i am maxed out on fuel....
Anyone know how much a stock pair of secondary injctors will cost used?
09-30-02, 03:39 PM
#9
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Get to a dyno asap
. Also go to the ecu section as they have a few maps there. I dynoed @356hp on stock injectors with plenty of injector left(on stock Injectors) and it was tuned to 11.3:1 AFR. So you are fine just need a good tuner and a dyno.
-Rikki
good luck
. Also go to the ecu section as they have a few maps there. I dynoed @356hp on stock injectors with plenty of injector left(on stock Injectors) and it was tuned to 11.3:1 AFR. So you are fine just need a good tuner and a dyno.-Rikki
good luck
09-30-02, 04:03 PM
#11
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Adding a higher capacity fuel pump and upping fuel psi helped to reduce my INJ % by 10%. ie Back when I was stock twins, adding the nippedenso pump allowed me to tune a lower inj % and maintain the same AFR.
You stock pump is probably dropping psi as you reach higher RPM's causing you to have to tune with a higher INJ% cycle to compensate for the drop in fuel pressure.
K
You stock pump is probably dropping psi as you reach higher RPM's causing you to have to tune with a higher INJ% cycle to compensate for the drop in fuel pressure.
K
09-30-02, 04:41 PM
#13
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Mahjik is right. Your pfc is just sending too much fuel. Also remember that 11.2 a/f is very rich....its where you need to be but its still very rich.
Back in the day when everyone was saying the injectors didnt max till 14.7psi of boost is when people were running upgraded ecu's. The upgraded ecu's alot of times are borderline safe. With all the bolt ons some are as lean as 12:1 so this is why the injectors didnt max untill 14.7.
Also, check you boost gauge not just your pfc boost level. Another thing from back in the day is when they were coming up with the 14.7 inj max theory they were mostly using boost gauges that read from the manifold not the sensor like the pfc does. Reading from the manifold shows a high boost. Your pfc is showing .89 ish but you boost gauge is probably hitting close to 14psi of boost.
If I were you I'd just make a few pulls on the dyno with a wideband and see how your a/f is. If your under 11.5 then you dont have anything to worry about.
STEPHEN
Back in the day when everyone was saying the injectors didnt max till 14.7psi of boost is when people were running upgraded ecu's. The upgraded ecu's alot of times are borderline safe. With all the bolt ons some are as lean as 12:1 so this is why the injectors didnt max untill 14.7.
Also, check you boost gauge not just your pfc boost level. Another thing from back in the day is when they were coming up with the 14.7 inj max theory they were mostly using boost gauges that read from the manifold not the sensor like the pfc does. Reading from the manifold shows a high boost. Your pfc is showing .89 ish but you boost gauge is probably hitting close to 14psi of boost.
If I were you I'd just make a few pulls on the dyno with a wideband and see how your a/f is. If your under 11.5 then you dont have anything to worry about.
STEPHEN
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