**Help** Car Stalling on Cold Start

[frozen_m5]

**Picture for attention, not my car**

2016 BMW M5

I’m currently experiencing an issue where the engine stalls on cold starts only. As soon as the car starts, it will run normally, then proceed to jump in rpm’s for a few seconds and completely shut off. Once the car is warm, it will start up perfectly fine. The car has a brand new motor, brand new injectors, upgraded rod bearings, etc. I’m not sure what the issue is, my mechanic is insisting it’s due to the tune being old (the one that was on the car when I bought it), however I have since flashed the car back to stock and the issue still remains. Any advice would be greatly appreciated.

Mods list- PG Intakes, Evolve Downpipes, Mishimoto Charge Pipes & Charge Coolers

[M5_Raz]

Known, common issue. I strongly suspect it’s the intakes. Just mildly feather the gas pedal for a couple of seconds to keep it around 1k rpm.

[frozen_m5]

Thanks, my only question to that is do you think that would cause any harm to the motor?

[M5_Raz]

I don’t think so, especially if you keep it at a constant rpm until it settles.

It’s more of an annoyance.

[M5_Raz]

More quality gas brands and higher octanes help. I am in California where gas is very bad, so we deal with it.

[frozen_m5]

Thanks brother!

[Flo1989]

You aren't alone. Same thing happens to me 9/10 cold starts and I do what M5_Raz suggested which is feather the throttle until it calms down. Some people reported their issue being fixed after cleaning off their MAF sensors but that didn't change anything for me. Maybe cold start delete could help?

[Bimmer56]

What I found is that s63tu are very sensitive to air intake. I removed my cai and put my factory air box and eliminated many of idle issues along with few others during cold starts.

[Flo1989]

Update: I had my cold start deleted because I'll be storing my car at a neighbors house this winter and I didn't want to shake down her home when I go start it a few times in the off season. I'm saying this because I now have zero cold start idle issues. It's a very boring, lackluster sound but the idle is perfectly smooth.

[M5_Raz]

Try it for a while first, it usually comes back, cold start or not.

Mine is smooth too on a freshly loaded tune/tune removal/cold start/no cold start.

[Flo1989]

Originally Posted by M5_Raz

Try it for a while first, it usually comes back, cold start or not.

Mine is smooth too on a freshly loaded tune/tune removal/cold start/no cold start.

Makes sense. So far so good, though. It's been a little over two weeks and about 30+ starts.

[supremexlonly]

I think it may be your HPFP and Injectors possibly, I just went through the same issues, and from what you are describing, it may be the reason for turning off. If the car struggles to stay on as well it can be the HPFP

[KurtsM5]

Cold start has one purpose, to heat up the cats for emissions purposes. Screw that. Leave that off forever.