fuel pump or injectors?

[danameisoj125]

well heres a little bit of background . im running dsmlink, 1000cc injectors, and a waly 255

turbo is sc63 on a 2.3 stroker.

problem

when out tuning today the car was doing about 18psi and was doing well. turned it up to 22psi . it started goin really lean . threw another 10% fuel into the mix no response. went to cleck the injector duty cycles and it was up at 148%.

my global is set at -52 percent to make up for the injector size so im wondering the reason why in duty cycles at up there.
could it be my pump dying? my injectors messed up?

theres no reason i should be excessively out of fuel like this . right now im at 16psi and at 86% inj duty cycle. we checked the regulator and everythings fine there.

any ideas?

 

[absolute_DSM]

Youre injectors cant run over 100%. Its physically impossible. 100% is wide open, no pulse. (I realize its not your fault, thats just interesting info)

Try a boost leak check.

Whats your base pressure set at by the way?

 

[zippyshoe]

The high injector duty cycles you are seeing would not be caused by any fuel delivery problem. If you are seeing 86% injector duty cycles at 16psi on 1000cc injectors, this points to some significant airflow metering issue - either a defective airflow sensor or a massive boost leak. If you can post a DSMLink log, that would probably be helpful to diagnose the problem. What type of airflow numbers (lbs/min) are you seeing?

 

[danameisoj125]

we didnt save the log. so i cant recall what it was. so it could be a problem with my gm maf?? theres no leaks. it was tested to 25psi before tuning began

 

[zippyshoe]

Did you calibrate the GM MAF? I'm not very familiar with the GM MAF's, but I recall that there is a calibration that should be performed when its used with DSMLink. You may want to check out the DSMLink Support Wiki for more information as well as the DSMLink forum.

 

[danameisoj125]

yes it was calibrated . everything was performing well . then out of nowhere the car started getting lean spikes . and did that . then we had to add alot more fuel and it wasnt reponding . my pump got louder so im thinking it could be my pump more than anything else.

 

[zippyshoe]

You may want to re-verify your base fuel pressure to determine if your fuel pump is functioning properly. You can also try turning on the pump manually with DSMLink and listening for it to respond.

I can't imagine though how low fuel pressure could affect you injector duty cycles. The injector pulsewidth is calculated by the ECU based on the airflow that the ECU sees. The ECU has no knowledge of the fuel pressure so it could not compensate for unexpected changes in fuel pressure. The ECU can only assume that the fuel pressure is maintained at the correct value.

 

[CanadianTSi]

Either your Fuel Pressure isn't rising with boost or you have an air metering issue.