Engine Stalling every cold start

[drx4mc]

https://vimeo.com/493476826
The roughest cold start I've ever seen. Video doesn't do it justice. The RPMs fluctuate by 5-600 rpms up to 1200 then drop back down to 600 continuously over and over until the engine stalls. 0 codes on the car but I've been getting around 6-8mpg and my cold start will always stall the car unless its being driven right away or revved. Its been getting worse with colder climate, but completely disappears after 1-2minutes of driving.

Performed a Smooth Running Test on ISTA+ and it showed all 8 injectors as within range hence the no codes. The issue seemed to start after I removed the cold start since i no longer have catted downpipes.

Current mods are:

Catless downpipes
Full 3in IPE exhaust
VRSF Intercoolers
methanol injection without Jb4 map0
gapped ngk plugs
DME stage 2 tune
bcm with jb4
upgraded SSP clutches
afe cold air intakes
stage 1 turbos
Cold start delete
Probably something Im missing but nothing out of the ordinary.

[M5_Raz]

Why not remove the cold start delete? Definitely seems like a problem with that.

[drx4mc]

Originally Posted by M5_Raz

Why not remove the cold start delete? Definitely seems like a problem with that.

I will to try temporarily and see if this remedies the issue. My next door neighbor and friend of many years politely asked if I could lower the exhaust sound as I work on call and my schedule is 24/7 mostly in the early am hours.

[drx4mc]

https://vimeo.com/493590712
Updated video of the car actually stalling this was 2 hours ago.

[M5_Raz]

Originally Posted by m6NYC

https://vimeo.com/493590712
Updated video of the car actually stalling this was 2 hours ago.

That doesn't sound good at all. This definitely looks like a software issue based on your description.

I would contact DME and tell them the issue. Who knows, maybe you got a corrupt file? If not, flash back to stock then tune again with the cold start delete enabled at the same time as flashing the tune.

Otherwise, I would try a different tune. See if you can explain to a different company that the engine is stalling with a DME cold start delete and would like to get their reassurance that it won't happen if you switch.

[drx4mc]

Originally Posted by M5_Raz

That doesn't sound good at all. This definitely looks like a software issue based on your description.

I would contact DME and tell them the issue. Who knows, maybe you got a corrupt file? If not, flash back to stock then tune again with the cold start delete enabled at the same time as flashing the tune.

Otherwise, I would try a different tune. See if you can explain to a different company that the engine is stalling with a DME cold start delete and would like to get their reassurance that it won't happen if you switch.

Thanks for your response, I sent DME a message. I will try to remove the cold start delete temporarily and see if this persists. I know it is an air-fuel ratio problem because the oscillations of the rpm get worse when i turn off the heat. With it on, slightly more gas consumption and marginally higher rpms, just high enough to prevent it from stalling.

[chadillac2000]

Could it be faulty o2 sensors? Did one get dinged up during the downpipe install? I know when I installed my downpipes recently, I had to order a special o2 removal socket tool to not mess up the wires during removal. Although I would imagine that would throw some kind of code.

I would have also started with the injectors, as that's typical symptom of a leaky fuel injector that eventually burns off after start up and runs okay afterwards. Perhaps it's just on the way out and not throwing a code yet and the cold start delete is just exacerbating the issue.

[drx4mc]

Originally Posted by chadillac2000

Could it be faulty o2 sensors? Did one get dinged up during the downpipe install? I know when I installed my downpipes recently, I had to order a special o2 removal socket tool to not mess up the wires during removal. Although I would imagine that would throw some kind of code.

I would have also started with the injectors, as that's typical symptom of a leaky fuel injector that eventually burns off after start up and runs okay afterwards. Perhaps it's just on the way out and not throwing a code yet and the cold start delete is just exacerbating the issue.

Thanks for your reply. I ended up buying a completely open ended but short stout o2 adapter removal tool from advance auto parts. Can't find the part number online, but it reroutes the cables sideways and out of the way completely. Best 30 bucks spent on tools ever, but your right its possible either of 4 could have gotten damaged. I will order both sets and replace after I reflash both DME's with a non-cold start delete.

[Competition C]

what's up M6....
im in brooklyn also and last month it happend once that i stalled out! i didn't think anything of it until i read your post !
keep this updated

[drx4mc]

Originally Posted by M5_Raz

Why not remove the cold start delete? Definitely seems like a problem with that.

Originally Posted by chadillac2000

Could it be faulty o2 sensors? Did one get dinged up during the downpipe install? I know when I installed my downpipes recently, I had to order a special o2 removal socket tool to not mess up the wires during removal. Although I would imagine that would throw some kind of code.

I would have also started with the injectors, as that's typical symptom of a leaky fuel injector that eventually burns off after start up and runs okay afterwards. Perhaps it's just on the way out and not throwing a code yet and the cold start delete is just exacerbating the issue.

Originally Posted by Competition C

what's up M6....
im in brooklyn also and last month it happend once that i stalled out! i didn't think anything of it until i read your post !
keep this updated

Hey guys, just to update this thread in case someone else has a similar issue.

Found out my smaller axillary coolant tank was slowly leaking, always seems empty. Turbo coolant lines were clean.
My stock plastic intercoolers had a crack and was leaking coolant into the engine.
Replaced them both with VRSF Charge Coolers and my problem is solved.
Also the AFE Cold Air Intakes were throwing off my fuel trim causing a 6-7miles per gallon. Reverted those back to stock with charcoal filter delete and my problems are solved!

[pish180]

Originally Posted by drx4mc

Hey guys, just to update this thread in case someone else has a similar issue.

Found out my smaller axillary coolant tank was slowly leaking, always seems empty. Turbo coolant lines were clean.
My stock plastic intercoolers had a crack and was leaking coolant into the engine.
Replaced them both with VRSF Charge Coolers and my problem is solved.
Also the AFE Cold Air Intakes were throwing off my fuel trim causing a 6-7miles per gallon. Reverted those back to stock with charcoal filter delete and my problems are solved!

Hey bud. I know this thread is old. But my m5 started stalling(surging idle) only during cold start (does it when its 30f outside or 100f). I can restart the car immediately after the stalled and it usually runs fine.

I didnt think much of it until your last update. My car just told me to fill coolant. I check thr main one (passenger side, on the engine) and its full. I check the alt one and it looks dry. Wondering if I have this same coolant line leak. Where did you find the leak? Attached pic of side thay was empty and assume the coolant side you are referring too. It seems to be completely covered. I also dont see any fluid on thr ground either. Do you recall the part number or another thread that discusses your fix?


Any help is appreciated. Ty!

[M5Rick]

No. You are showing the main engine block cooling reservoir in the top right hand corner of the engine bay. It's normal to top it up once in a while with a 50/50 mix of only BMW a/freeze mix and distilled water to the bottom of the filler pipe.

The oblong coolant reservoir for the turbo intercoolers and DME's is to the left of the engine bay.

[M5Rick]

The blue BMW 87 lifetime life coolant is for the M5 F10, putting in the wrong coolant can lead to a malfunction. pn 83 51 2 355 290