SMG Stalling After Alpha-N karbonious airbox conversion

[0-60motorsports]

Hey guys

I have a 2003 11k Mike smg m3 that recently got a full SuperSprint headers back exhaust system, karbonius airbox And alpha N tune done. Did a 20 mile test drive and drove like a dream. After about 30-35 miles car started stalling after coming to a stop or even just standing still and when you started moving even slightly in 1st gear. When the car had US headers and stock intake it didn’t do that.

I have checked all the airbox hoses everything is nice and tight with no air leaks. No leaks in general. O2 sensors are in the correct positions. No errors stored in the car as scanned today.

Now I know the car is mafless already so what other things could be causing this? Any thoughts of any of you have experienced the Same thing. Thanks.

[Obioban]

MAP converted or straight Alpha N?

[0-60motorsports]

MAP converted or straight Alpha N?

Straight Alpha-N

[0-60motorsports]

I have this faulty code. Coolant sensor in the block. Could this be the cause of the stalling?

[liam821]

I'd think the computer takes coolant (engine temperature) into considering when dealing with the amount of fuel/timing it gives the engine, so I'd probably start by fixing that sensor/code and seeing if it improves.

[0-60motorsports]

I’m working on something will update soon.

[eacmen]

I'd think the computer takes coolant (engine temperature) into considering when dealing with the amount of fuel/timing it gives the engine, so I'd probably start by fixing that sensor/code and seeing if it improves.

That is only on cold start (open loop). Once the engine warms up coolant temp is not considered and ecu should be running on AFRs from the O2 sensors. I assume even Alpha-N uses the O2s.

[SliM3]

See if you can check your AFR. Could be fueling when transitioning from throttle bodies to idle control valve. There are three separate fueling strategies: idle, steady state, and full load. They all have to seamlessly transition between one another while maintaining a consistent AFR. You can also try changing values in the alpha-n map as those numbers directly influence injector pulsewidth.

[0-60motorsports]

See if you can check your AFR. Could be fueling when transitioning from throttle bodies to idle control valve. There are three separate fueling strategies: idle, steady state, and full load. They all have to seamlessly transition between one another while maintaining a consistent AFR. You can also try changing values in the alpha-n map as those numbers directly influence injector pulsewidth.

Hey brother, yes done. Reset adaptations, adjusted and drove more than 65 miles straight. No issues so far touch wood and thank God.