450's maxed out?

[DaveDSM]

walbro 255, stock 450 injectors, b&m commandflo set at 50psi, 14b at 13psi. 5 knob AFC, +2% at 4k, and 5600.

No knock at all in 3rd anymore at 2 psi higher than last time i logged, so the AFC is working. But now my o2's are low as hell. peak o2 is .70v. My fuel trims are low, med, high.

low: 118.7%
med: 110%
high: 117.9%

timing hit 19 degrees with no knock under full boost up to redline.

Now, is it really possible for the stock 14b to be maxing out my injectors like this, even at 50psi base? Or coudl it be that my o2 sensor is dying, lowering the o2 readings, causing the ecu to run the injectors harder to compensate for a non-existant lean condition?
or what else? any ideas?

 

[nine5raptor]

The ecu ignores the 02s at wot, so it will not affect your tune there.

Other than that it looks like the 02 is on its way out.

The fact that you had no knock means you are fine in terms of having enough fuel.

Also 13 psi is pretty low to be maxxing injectors, especially at 50 psi base.

I think you are good to turn the boost up a bit more.

 

[DaveDSM]

Originally posted by nine5raptor
The ecu ignores the 02s at wot, so it will not affect your tune there.

Other than that it looks like the 02 is on its way out.

The fact that you had no knock means you are fine in terms of having enough fuel.

Also 13 psi is pretty low to be maxxing injectors, especially at 50 psi base.

I think you are good to turn the boost up a bit more.

Awesome, I'm gonna run 18psi. I'm just wondering about the injectors because they're above 100%

 

[nine5raptor]

Originally posted by DaveDSM
Awesome, I'm gonna run 18psi. I'm just wondering about the injectors because they're above 100%

hmmm, yeah. I just thought about that. I think I misread the intent of your original post.

You are at a higher base and your fuel trims are positive.
I bet the dying 02 sensor is causing that. Just watch your knock at wot and I would think about getting a new 02 sensor.

 

[Tyler_Baker]

Originally posted by DaveDSM
Awesome, I'm gonna run 18psi. I'm just wondering about the injectors because they're above 100%

I run my base FP @ 36-37lbs, 255 Walbro HP, 450's, SAFCII, 14B@15 psi at the top of third I am pulling 0 knock and 21 degrees @ 6873rpm. Injector duty cycle was at 104%. Seems like running 50psi of base fuel pressure should make your DC way lower than mine. Of course everyone's car is different. My buddies D series is running 10psi of boost and running 110% DC on 450cc, so it's possible. Just some food for thought.

 

[punisha]

damn i wish i knew what yall was alkin bout

 

[kpt4321]

Originally posted by punisha
damn i wish i knew what yall was alkin bout

Well that doesn't help.

What is it that you don't understand? Search for it, check the VFAQ and the 1000FAQ, and if you still don't get it ask questions! Just make sure you do a little research first.

 

[DaveDSM]

Originally posted by Tyler_Baker
I run my base FP @ 36-37lbs, 255 Walbro HP, 450's, SAFCII, 14B@15 psi at the top of third I am pulling 0 knock and 21 degrees @ 6873rpm. Injector duty cycle was at 104%. Seems like running 50psi of base fuel pressure should make your DC way lower than mine. Of course everyone's car is different. My buddies D series is running 10psi of boost and running 110% DC on 450cc, so it's possible. Just some food for thought.

Yeah, I got a budget AFPR so I can't lower my base. The Walbro knockedmy base up to 47 psi, so I just went to 50 and called it a day.

Looks like I'm gonna be putting in a new o2 sensor over break. Thanks for your help guys.

 

[DSM_23]

Ya, replace your O2. Its fixin to crap out.

 

[Tyler_Baker]

Originally posted by DSM_23
Ya, replace your O2. Its fixin to crap out.

Get the NTK o2 sensor from the dealer, My free "Borg Warner" o2 sensor fouled in three days. A bosch could be a good choice as well, as long as they are heated.

 

[DJ23GSX]

I've got 450's and a walbro 255 with a ported 16g@16psi and the most my injectors have seen was 91% They usually stay around 87-88%. My timing is around 19* and 0 knock and 02v are between .84-.88.

 

[crankbender]

First check your grounds to the exhaust under the car. Did you put em back on after you changed your exhaust?

Secondly you have done alot of mods to the car that will affect flow and VE. While you are only running 13psi your VE is much higher than when stock. That said you will flow alot more air than a stock car with an intake pressure of 13 psi.


It is possible you are maxing out the injectors.

What does your duty cycle look like at lower RPMs. Do you ever get higher O2 readings at lower RPMs. If your ok never goes op check that darn ground. you could be trying to ground through the block.

 

[4g63tsiawd]

is there any other way to ground the strap that goes to the down pipe my bracket broke that is on the down pipe so i cant connect it there anymore