Injector duty cycle

[Impala ss sleeper]

I have a 2005 impala l67,xp cam,gen v ,northstar tb,3.4 pulley,speed daddy headers,and my injector cycle was at 125 at wot and got 5*knock during high rmp and shift then it would drop down to 2* any suggestions?Oh i still have stock l67 injectors.

 

[dsmuts]

What kind of tune do you have?

 

[afallucco]

As I said in the other thread Any knock is bad even a few degrees. What tuning have you done and do you have someone who can tune the car for you?

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[Impala ss sleeper]

hp tuning

 

[afallucco]

Have you done a wideband tune and what's your afr?

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[Impala ss sleeper]

have to ask my tuner i think he said around 12?? cont remember not done a wideband yet what should the afrs be

 

[rynoman03]

11.1-11.3ish at WOT

I mean you can go leaner but that's upto you. Sounds like your running too lean!

 

[Tuner-Extraordinaire]

pulley is too small. -- if your duty cycles are 125 you're too rich.

 

[Impala ss sleeper]

yea i bought some 60lbs seimens injectors cheap goin to put them on and tune see what happens

 

[rynoman03]

Ya but he said his tuner said the afr was around 12. That's kinda lean if that's true. With the xp it almost sounds like he can't get enough fuel at 125 inj duty.

 

[Impala ss sleeper]

its too small even with the xp cam??

 

[rynoman03]

I think it's fine i personally think your running out of injector and going lean. I can't see that without a scan though.

 

[Impala ss sleeper]

thanks for your help and info guys goin to install injectors and scan will post more info tomorrow

 

[Tuner-Extraordinaire]

still seems rich 125% duty -- you're def running out of injectors though

 

[rynoman03]

Don't forget you have to change your tune for those injectors. You just can't slap em on without doing anything to the computer. I'm sure you know this but i'm just telling you just in case ya know.

 

[darkhorizon]

still seems rich 125% duty -- you're def running out of injectors though

The 04+ read incorrectly... He is still well within his functional range on that car... a 3.4 pulley with any cam will not max out stock injectors on any GTP... He can command a bit more fuel if he is really lean without hurting anything.

I imagine there is a bunk maf file on there that was loaded for the northstar that is leaning things out (because it was richened too much at idle).

 

[Impala ss sleeper]

installed 60lbs injects duty cycle is at 48% now and AFRs at 11.3 wot but i still get about 6* then it goes back to 1*

 

[Tuner-Extraordinaire]

burst kr.

 

[afallucco]

Ya but he said his tuner said the afr was around 12. That's kinda lean if that's true. With the xp it almost sounds like he can't get enough fuel at 125 inj duty.

You want around 11.5 afr for non intercooled and 12 for intercooled. In this case he's lean

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