105% injector duty cycle?

Maverick31 · 03-16-2008, 11:18 AM

Hey guys, I just got done messing with my tune using ECU Flash and after just increasing the boost up to around 16.4 psi in 3rd, and peaking to 17 psi in 5th and not touching the fuel maps, I'm showing a peak of 105% injector duty cycle durring log!
Now, I just bought this car a few weeks ago, and I have done nothing besides put a K&N drop filter in, so why am I seeing such crazy numbers?
I would have thought this was a goof, but when I checked my A/F ratio's, the car is leaning itself out to 11.02-1 while hitting max boost. The stock target A/F ratio is around 10.8-1.

This is kind of freaking me out, I sure don't want to fry an injector. Obviously something is wrong here.

***Szumita*** · 03-16-2008, 11:22 AM

get a new fuel pump.

nhat · 03-16-2008, 11:25 AM

you won't fry an injector running 105% IDCs.

i think you need to calibrate the maf due to installing the air filter. log both your maf voltage and maf g/s.

***Szumita*** · 03-16-2008, 11:27 AM

the stock pumps are basically not too good on the sti. each one is slightly different car to car. same with injectors. thats why those two are needed when you get decent power over stock.

Maverick31 · 03-16-2008, 11:27 AM

Thanks for the quick responses!
How do you calibrate the MAF?

BTW- The car only has 26K miles on her, I would hope that the stock fuel pump wouldn't already be giving out.

Maverick31 · 03-16-2008, 11:28 AM

Quote:

Originally Posted by Szumita

the stock pumps are basically not too good on the sti. each one is slightly different car to car. same with injectors. thats why those two are needed when you get decent power over stock.

I heard that it was difficult to make over 310WHP with the stock fuel pump and injectors... but I haven't done anything but increase boost a bit and put a new filter in. This just seems odd.

***Szumita*** · 03-16-2008, 11:31 AM

yeah, some are different than others, its been recorded. the pump isnt giving out, its just maxed out.

im installing a walbro pump today before my tune, because at around stage 2, its completly maxed out. injectors arent as bad. if i were you, just spend the 80-90$ on a walbro pump and call it a day.

Maverick31 · 03-16-2008, 11:37 AM

Well, can you or someone else tell me how to calibrate the maf so I can just try it for the hell of it?

BTW- Do you know if the dealer would care (as far as warranty work goes) if I swapped out fuel pumps? And would the drivability change after putting in a 255lb pump?

***Szumita*** · 03-16-2008, 11:43 AM

i dont think the dealer could tell unless they took it out, which would take a bit lol.

but as far as calibrating the maf, i have no clue.

Deuce Cam · 03-16-2008, 11:48 AM

I hate to play devil's advocate here and I'm no expert by any means, but isn't the idea of just changing the fuel pump to lower IDC's debatable? In all fairness I've only spoke to one protuner regarding this. For example, he mentioned that changing to a walboro fuel pump for a stage 2 tune will not lower one's IDCs.

nhat · 03-16-2008, 12:03 PM

a fuel pump does not lower IDCs. it just gives you headroom. injectors only flow so much so they become the bottleneck. many stage 2 sti's easily make 310whp on just a turboback and protune.

by logging both maf voltage and maf g/s, you can adjust the maf calibration. in romraider or enginuity, adjust the values in the maf scaling table according to your logs.

STiLLsLow · 03-16-2008, 12:09 PM

may want to look into this thread, havent read the whole thing but im sure its very helpful. Walbro does not lower Injector Duty Cycles on Stage 2 setup

03-16-2008, 11:18 AM	#1
Maverick31 Grassroots STI Racer Car: Blue 2006 WRX STi Fav Mod: Protuned Stage 2 Location: Port Huron, Michigan Posts: 523 Join Date: Mar 2008 Trader Rating: (0)	105% injector duty cycle? Hey guys, I just got done messing with my tune using ECU Flash and after just increasing the boost up to around 16.4 psi in 3rd, and peaking to 17 psi in 5th and not touching the fuel maps, I'm showing a peak of 105% injector duty cycle durring log! Now, I just bought this car a few weeks ago, and I have done nothing besides put a K&N drop filter in, so why am I seeing such crazy numbers? I would have thought this was a goof, but when I checked my A/F ratio's, the car is leaning itself out to 11.02-1 while hitting max boost. The stock target A/F ratio is around 10.8-1. This is kind of freaking me out, I sure don't want to fry an injector. Obviously something is wrong here. This ad is not endorsed by this member. Please register or login to hide this ad. Last edited by Maverick31 : 03-16-2008 at 11:30 AM.

03-16-2008, 11:22 AM	#2
*Szumita* i eat cones Car: 08.5 GTI MKv Fav Mod: 18x8 Location: ma & ri Posts: 6,479 Join Date: Oct 2006 Trader Rating: (16)	Re: 105% injector duty cycle? get a new fuel pump.

03-16-2008, 11:25 AM	#3
nhat Professional STI Driver Car: 04 sti Fav Mod: enginuity tuned Location: NoVA Posts: 406 Join Date: Aug 2007 Trader Rating: (0)	Re: 105% injector duty cycle? you won't fry an injector running 105% IDCs. i think you need to calibrate the maf due to installing the air filter. log both your maf voltage and maf g/s.

03-16-2008, 11:27 AM	#4
*Szumita* i eat cones Car: 08.5 GTI MKv Fav Mod: 18x8 Location: ma & ri Posts: 6,479 Join Date: Oct 2006 Trader Rating: (16)	Re: 105% injector duty cycle? the stock pumps are basically not too good on the sti. each one is slightly different car to car. same with injectors. thats why those two are needed when you get decent power over stock.

03-16-2008, 11:27 AM	#5
Maverick31 Grassroots STI Racer Car: Blue 2006 WRX STi Fav Mod: Protuned Stage 2 Location: Port Huron, Michigan Posts: 523 Join Date: Mar 2008 Trader Rating: (0)	Re: 105% injector duty cycle? Thanks for the quick responses! How do you calibrate the MAF? BTW- The car only has 26K miles on her, I would hope that the stock fuel pump wouldn't already be giving out.

03-16-2008, 11:31 AM	#7
*Szumita* i eat cones Car: 08.5 GTI MKv Fav Mod: 18x8 Location: ma & ri Posts: 6,479 Join Date: Oct 2006 Trader Rating: (16)	Re: 105% injector duty cycle? yeah, some are different than others, its been recorded. the pump isnt giving out, its just maxed out. im installing a walbro pump today before my tune, because at around stage 2, its completly maxed out. injectors arent as bad. if i were you, just spend the 80-90$ on a walbro pump and call it a day.

03-16-2008, 11:37 AM	#8
Maverick31 Grassroots STI Racer Car: Blue 2006 WRX STi Fav Mod: Protuned Stage 2 Location: Port Huron, Michigan Posts: 523 Join Date: Mar 2008 Trader Rating: (0)	Re: 105% injector duty cycle? Well, can you or someone else tell me how to calibrate the maf so I can just try it for the hell of it? BTW- Do you know if the dealer would care (as far as warranty work goes) if I swapped out fuel pumps? And would the drivability change after putting in a 255lb pump?

03-16-2008, 11:43 AM	#9
*Szumita* i eat cones Car: 08.5 GTI MKv Fav Mod: 18x8 Location: ma & ri Posts: 6,479 Join Date: Oct 2006 Trader Rating: (16)	Re: 105% injector duty cycle? i dont think the dealer could tell unless they took it out, which would take a bit lol. but as far as calibrating the maf, i have no clue.

03-16-2008, 11:48 AM	#10
Deuce Cam STI Driver Car: 06 STI Location: Phoenix Posts: 216 Join Date: May 2006 Trader Rating: (0)	Re: 105% injector duty cycle? I hate to play devil's advocate here and I'm no expert by any means, but isn't the idea of just changing the fuel pump to lower IDC's debatable? In all fairness I've only spoke to one protuner regarding this. For example, he mentioned that changing to a walboro fuel pump for a stage 2 tune will not lower one's IDCs.

03-16-2008, 12:03 PM	#11
nhat Professional STI Driver Car: 04 sti Fav Mod: enginuity tuned Location: NoVA Posts: 406 Join Date: Aug 2007 Trader Rating: (0)	Re: 105% injector duty cycle? a fuel pump does not lower IDCs. it just gives you headroom. injectors only flow so much so they become the bottleneck. many stage 2 sti's easily make 310whp on just a turboback and protune. by logging both maf voltage and maf g/s, you can adjust the maf calibration. in romraider or enginuity, adjust the values in the maf scaling table according to your logs.

03-16-2008, 12:09 PM	#12
STiLLsLow Professional STI Driver Car: 05 AW STi Location: ATL y0 Posts: 401 Join Date: Apr 2005 Trader Rating: (5)	Re: 105% injector duty cycle? may want to look into this thread, havent read the whole thing but im sure its very helpful. Walbro does not lower Injector Duty Cycles on Stage 2 setup This ad is not endorsed by this member. Please register or login to hide this ad.