running very lean until full warm

[need2boostpsi]

alright whenever i first start my car cold it starts and idles high for about 3 seconds then idle starts to drop and then stumbles and dies. the only way i can keep it running is to pump the gas pedal. If i drive off after a minute of pumping the gas it drives fine wideband shows 14.7 +/- and i can come to a stop and It idles normal. my fuel trims once warm are within 5% +/-. wideband when car is cold is anywhere from 15.6-16.5(as lean as my WB will go), once warm its cycling around 14.5. I'm so new to tuning that i dont know if a tune can fix this, what could cause this? BTW car has no boost leaks and I have DSM Link with Delphi 950cc Injectors.

 

[bboyalan]

You said your fuel trims are 5% +/-.... of 100% I'm assuming? What "high rpm" are you reaching on the lean cold start? You could try adding fuel in 1% increments to that spot's low fuel trim until the car no longer stumbles. At least that's how I would do it working w/ a datalogger and s-afc heh.

 

[Demon33]

alright whenever i first start my car cold it starts and idles high for about 3 seconds then idle starts to drop and then stumbles and dies. the only way i can keep it running is to pump the gas pedal. If i drive off after a minute of pumping the gas it drives fine wideband shows 14.7 +/- and i can come to a stop and It idles normal. my fuel trims once warm are within 5% +/-. wideband when car is cold is anywhere from 15.6-16.5(as lean as my WB will go), once warm its cycling around 14.5. I'm so new to tuning that i dont know if a tune can fix this, what could cause this? BTW car has no boost leaks and I have DSM Link with Delphi 950cc Injectors.

A cold O2 sensor takes a few moments to warm up enough to begin accurately reading the air-fuel ratio. If you allow it to warm up a bit while keeping the idle up by pumping the pedal, does the AFR begin cycling normally with a better idle?

The fuel pressure solenoid momentarily raises fuel pressure during cold startup, adding more fuel to help the engine idle and warm up. Check that this is operating properly and that there are no leaks in the vacuum hose. You could simulate the action of the FPS by disconnecting and plugging the vacuum hose on the fuel pressure regulator. Try this and see if you have an easier time starting the car the next time the engine is cold.

Also, on cold stratup, the FIAV is used to raise the idle by allowing more air passed the throttle body. And many cold start problems can also be linked to a bad coolant temperature sensor.

 

[need2boostpsi]

You said your fuel trims are 5% +/-.... of 100% I'm assuming? What "high rpm" are you reaching on the lean cold start? You could try adding fuel in 1% increments to that spot's low fuel trim until the car no longer stumbles. At least that's how I would do it working w/ a datalogger and s-afc heh.

yeah 100% when fully warmed, around 1300 for a second, and i have link V3, if i pull fuel then my trims are off when the car is warmed up.

you might want to check your o2 sensor..maybe just maybe..

02 sensor is a new denso and it cycles when the mixture becomes rich enough.

A cold O2 sensor takes a few moments to warm up enough to begin accurately reading the air-fuel ratio. If you allow it to warm up a bit while keeping the idle up by pumping the pedal, does the AFR begin cycling normally with a better idle?

The fuel pressure solenoid momentarily raises fuel pressure during cold startup, adding more fuel to help the engine idle and warm up. Check that this is operating properly and that there are no leaks in the vacuum hose. You could simulate the action of the FPS by disconnecting and plugging the vacuum hose on the fuel pressure regulator. Try this and see if you have an easier time starting the car the next time the engine is cold.

Also, on cold stratup, the FIAV is used to raise the idle by allowing more air passed the throttle body. And many cold start problems can also be linked to a bad coolant temperature sensor.

have a AFPR, base pressure is at 43.5 +/- a little bit. when the car warms up o2 cycles becuase the mixture becomes rich enough. no Fiav, I have a Fiav block-off plate. I'm going another TB and ISC, and a different MAS. thanks for all the replys so far and keep them coming!