[WaleeF30]

Hello guys,

Hope everyone is doing well. I have a 2014 335xi with the n55 engine.

Recently was driving and got a low coolant light so I figured no big deal I'll top it off, then the engine started heating up luckily I got home a mile after it gave me the overheating warning, opened the hood and the upper radiator to expansion tank hose was broken and coolant all over the place.

So I went ahead and replaced the hose and refilled my coolant and did the bleeding procedure.

The first time I started it up after It was "fixed" the car cranked, died for a sec, rev'd up to like 2k, then went back down to idle rpms and was normal after that. This happened like 4 more times since the coolant issue 20 days ago.

It did not throw any CEL or anything like that and this does not happen every time I start the car, so not sure how to track down the cause.

Sorry if the thread was long but I wanted to put you guys in perspective of what happened.

P.S. only mods I have are drop in air filter, muffler delete, and sport transmission coding.

Thanks!

[Zanity]

Your symptom doesn't sound like it has anything to do with the coolant that's for sure. Honestly could be anything at this point, starter, spark plugs, ignition coils, VANOS, LPFP, MAF etc... Car doesn't throw any codes until the problem becomes major, that's normal.

[WaleeF30]

Originally Posted by Zanity

Your symptom doesn't sound like it has anything to do with the coolant that's for sure. Honestly could be anything at this point, starter, spark plugs, ignition coils, VANOS, LPFP, MAF etc... Car doesn't throw any codes until the problem becomes major, that's normal.

Thanks for the reply!

Yeah it was weird that it started happening right after I had the coolant and overheating issue.

I'm gonna try to change out the coils and sparks to see if that helps.

Car has 106k and I haven't changed the coils since I bought it at 70k so I'm sure it's time for it lol

[Zanity]

You should read my post too on rough idle / stalls, see if it helps:

https://f30.bimmerpost.com/forums/sh....php?t=1727053

[davidr3]

Originally Posted by WaleeF30

Thanks for the reply!

Yeah it was weird that it started happening right after I had the coolant and overheating issue.

I'm gonna try to change out the coils and sparks to see if that helps.

Car has 106k and I haven't changed the coils since I bought it at 70k so I'm sure it's time for it lol

Visually inspect your CP too, make sure it isn't cracked.

[WaleeF30]

Originally Posted by davidr3

Visually inspect your CP too, make sure it isn't cracked.

Charge pipe looks fine, the car runs smooth after

[WaleeF30]

Just want to update this post since this is still an issue, I replaced the coils in hopes of fixing it but it didn't.

I don't know maybe when the coolant splashed all over the engine bay if it hit any sensors or wiring that is causing this.

I don't know what else to check.

I will try to take a video of what it's doing but it doesn't happen all the time, guess I'll have to take a video every time I start the car lol

[cfm56d7b]

Did you have a chance to use a code scanner to identify any stored faults?

[WaleeF30]

Originally Posted by cfm56d7b

Did you have a chance to use a code scanner to identify any stored faults?

Yeah I have BimmerLink, I found the following codes in error memory.

The exhaust flap I know about since I unplugged it, but not sure what the other codes are.

They are not active tho so I don't know if that matters.[IMG][/IMG]

[jackstrath]

AUC is your air re-circulation sensor, Measures air quality, normally hides near the airbox but im not sure where it is on F30, google will tell you. What is interesting is that its showing as a short, which might be because of the coolant, but then as we dont know when that code appeared it could be completely unrelated.

[WaleeF30]

Originally Posted by jackstrath

AUC is your air re-circulation sensor, Measures air quality, normally hides near the airbox but im not sure where it is on F30, google will tell you. What is interesting is that its showing as a short, which might be because of the coolant, but then as we dont know when that code appeared it could be completely unrelated.

Im leaning towards it being unrelated, even if it was the coolant that caused the AUC error it still doesn't explain the choke at startup

[WaleeF30]

Was able to get a video of it. Apparently it happens every time I leave the car off for 1-2 hours or longer.

Hopefully you can hear it at the beginning of the video, you can also see the rpms jump a bit then it calms down.

https://streamable.com/tsp4vi

[bloodline129]

Mine does the same thing, not always but definitely on cold starts.

2015 f32 85k km.

Only difference is, mine drops to 500rpm and surges back to 1200 and stabilizes.

No codes... still figuring out the best approach. As there is no codes and I still have warranty. I may just keep the recording and wait for it to be covered when something actually throws a code...

Annoying

[davidr3]

Originally Posted by WaleeF30

Was able to get a video of it. Apparently it happens every time I leave the car off for 1-2 hours or longer.

Hopefully you can hear it at the beginning of the video, you can also see the rpms jump a bit then it calms down.

https://streamable.com/tsp4vi

That doesn't seem extremely abnormal, don't some people code that shit in with a gts roar or whatever it's called lol.

[WaleeF30]

Originally Posted by bloodline129

Mine does the same thing, not always but definitely on cold starts.

2015 f32 85k km.

Only difference is, mine drops to 500rpm and surges back to 1200 and stabilizes.

No codes... still figuring out the best approach. As there is no codes and I still have warranty. I may just keep the recording and wait for it to be covered when something actually throws a code...

Annoying

Did anything happen at the same time it started like me having the coolant hose burst or was mine just a coincidence?

I hope someone on here had this issue and figured it out.

[WaleeF30]

Originally Posted by davidr3

That doesn't seem extremely abnormal, don't some people code that shit in with a gts roar or whatever it's called lol.

I don't think the roar sounds anything like the car choking tho, and I sure haven't coded anything in to make it do this lol would never

[davidr3]

Originally Posted by WaleeF30

I don't think the roar sounds anything like the car choking tho, and I sure haven't coded anything in to make it do this lol would never

I may be extremely wrong with this, so wait for someone to clarify, but after the amount of coolant you lost + topping it off, does the system need to be bled?

I don't see how it would explain the startup though but who knows, these cars are weird sometimes.

[WaleeF30]

Originally Posted by davidr3

I may be extremely wrong with this, so wait for someone to clarify, but after the amount of coolant you lost + topping it off, does the system need to be bled?

I don't see how it would explain the startup though but who knows, these cars are weird sometimes.

Yeah they do, I actually had to bleed it twice because I lost so much coolant that I had to fill it up, bleed it (which sucked in all the extra coolant in the reservoir), fill it up again then bleed it one last time.

[bloodline129]

Originally Posted by WaleeF30

Did anything happen at the same time it started like me having the coolant hose burst or was mine just a coincidence?

I hope someone on here had this issue and figured it out.

Not a thing, no mechanical problems whatsoever. Just started happening last few weeks.

Also mine does it very random. Could be after few hours sitting idle or a whole night. But also doesn't do it everytime it's sits through the night.... ughhh lol... maybe 2/3 times a week and sporadic AF

[WaleeF30]

I tried putting techron fuel system cleaner and that didn't do anything.

Driving me crazy..

[dmaxdmax]

Did you clean your belts off of coolant? It's very slippery stuff. Not sure how easy it is to get to your belt...on the manual it's pretty easy. You could mist with a dishwashing liquid like Dawn in water and then rinse off? That's one guess.

I wish I'd seen this before you replaced coils. A shot coil cause the motor to stutter noticeably and lose power.

Could coolant have been sucked into your air filter. Did you check to see it's dry and that the maf is clean (use maf cleaner).

Good luck!

[bloodline129]

This is what I'm experiencing, no codes no issues after, hasn't stalled yet.

Not sure where to start.