[meddlemaker]

2020 M340i -- if I park for a while and leave the engine running, and then attempt to drive away, there is a definite lag when I'm trying to pull away. The car almost stalls and lags for a good 2-3 seconds before acceleration returns to normal.

This only happens if I've been idling a while, parked with the engine running. No issues from a cold start or if I stop briefly (like at a red light).

I used to own a 2016 328i that I recall doing the same thing, and I believe it was a fuel pump or filter issue but I can't remember which.

Anyone know?

[zazzau]

Originally Posted by meddlemaker

2020 M340i -- if I park for a while and leave the engine running, and then attempt to drive away, there is a definite lag when I'm trying to pull away. The car almost stalls and lags for a good 2-3 seconds before acceleration returns to normal.

This only happens if I've been idling a while, parked with the engine running. No issues from a cold start or if I stop briefly (like at a red light).

I used to own a 2016 328i that I recall doing the same thing, and I believe it was a fuel pump or filter issue but I can't remember which.

Anyone know?

I have a 2021 M340xi but I don't have this problem. Record the issue and take it in for service. Better yet test drive with foreman and show them the problem. Goodluck.

[Benjamin_Nicholas]

I remember my M340i having a turbo lag in very specific situations, one of which was when turning from a stop onto an incline.

It wasn't Audi bad (which is god awful), but it wasn't fun, especially when you needed that turbo to kick in fast due to traffic behind you.

[Montaver]

Why are you parked with the engine running?

[oonowindoo]

1. were you in comfort mode?
2. is your Auto Hold on?
3. was the ASS activated.

Some minor lag with turbo cars in certain situations is perfectly normal. I never believe when people say "There is absolutely no turbo lag"
M340i with 48v is much much improved over F30 in term of turbo lag.

At the end of the day, there are still few occasions even with the 48v when the turbo is not spooling fast enough for our needs.

I dont think that is what you are describing here. If you are trying to launch the car from dead stop, you need to build up your boost first...

[oonowindoo]

Originally Posted by Benjamin_Nicholas

I remember my M340i having a turbo lag in very specific situations, one of which was when turning from a stop onto an incline.

It wasn't Audi bad (which is god awful), but it wasn't fun, especially when you needed that turbo to kick in fast due to traffic behind you.

I always ask myself when i experience similar situations that how come there is always turbo lag when i need my full boost the most and there is rarely any lag when i dont need it.

Sport+ removes most of the lags, but unlike some people, i dont normally drive in Sport+... So it does not help when i actually need my boost

[meddlemaker]

Originally Posted by oonowindoo

1. were you in comfort mode?
2. is your Auto Hold on?
3. was the ASS activated.

Some minor lag with turbo cars in certain situations is perfectly normal. I never believe when people say "There is absolutely no turbo lag"
M340i with 48v is much much improved over F30 in term of turbo lag.

At the end of the day, there are still few occasions even with the 48v when the turbo is not spooling fast enough for our needs.

I dont think that is what you are describing here. If you are trying to launch the car from dead stop, you need to build up your boost first...

Yeah, I don't think this is a turbo lag issue - this is the engine almost providing zero power when moving from a dead stop after idling for more than 15 minutes or so.

I'm almost always in comfort mode, never use Auto Hold, don't know what ASS stands for.

[oonowindoo]

Auto Start/Stop.

BTW: you probably should turn the car off if it idles for 15 mins.

[zazzau]

Originally Posted by oonowindoo

Auto Start/Stop.

BTW: you probably should turn the car off if it idles for 15 mins.

What if you're idling in traffic for 15 or so minutes?

[Conan-]

I have experienced somewhat similar issues! It felt like the car is hesitant to accelerate from a standstill and likely not a turbo lag issue.. haven’t really been able to reproduce it but it does feel dangerous especially if trying to rejoin traffic and this happens out of the blue

[HighlandPete]

15 minutes idling with a turbo engine... Most likely as simple as heat soak. Hot air, the enemy of building turbo boost.

Still wondering why anyone would idle an engine for 15 minutes.

[zazzau]

I idled my M340xi twice for 15 minutes (with A/C running the whole time) I can't reproduce what OP is describing. Car is super responsive each time - and no I don't have the cooling package.

Highly doubt it has anything to do with heat soak though based on OPs description. AFAIK with heat soak, there's a lag in turbo boost/acceleration until the engine eventually "cools" - in OPs case, this is happening only when pulling away from parking.

Perhaps others can confirm. Probably affects just a subset of our cars or only happens under certain conditions

[HighlandPete]

Originally Posted by zazzau

I idled my M340xi twice for 15 minutes (with A/C running the whole time) I can't reproduce what OP is describing. Car is super responsive each time - and no I don't have the cooling package.

Highly doubt it has anything to do with heat soak though based on OPs description. AFAIK with heat soak, there's a lag in turbo boost/acceleration until the engine eventually "cools" - in OPs case, this is happening only when pulling away from parking.

Perhaps others can confirm. Probably affects just a subset of our cars or only happens under certain conditions

When suggesting simply heat soak, ought to clarify. May be the trigger to unusual sensor values or input. Requires time to interpret, rather than the heat dispersal itself.

Agree on only some cars, or certain conditions may generate this delay.

[oonowindoo]

Originally Posted by zazzau

What if you're idling in traffic for 15 or so minutes?

Traffic moves... even at 1 mph, it still moves.

i dont know how you can idle for 15 mins in traffic without moving. You could literally just turn off the car and walk around in those situations like we have seen on TV. I personally have never experienced something like that... the car might idle for 2-3 mins at most then it will move... at least a few feet.

Even when the freeway was closed, we would crawl to the exit but still never idle for 15 mins straight without moving.


Also per OP, he chokes for 2-3 secs, that is a LONG time, you will get honked most of the time if you dont move for 3 secs when the light turns green.

Even if i needed to stay in the car for 15 mins because outside is 110 degrees here while waiting for someone, that still does not justify 3 secs delay. Our cars are automatic, it moves forward the moment you let go the brake.

I dont see it is realistic to wait for someone for 15 mins and WOT the moment he/she gets in...

We need OP to provide more Info....

[zazzau]

Originally Posted by oonowindoo

Traffic moves... even at 1 mph, it still moves.

i dont know how you can idle for 15 mins in traffic without moving. You could literally just turn off the car and walk around in those situations like we have seen on TV. I personally have never experienced something like that... the car might idle for 2-3 mins at most then it will move... at least a few feet.

Even when the freeway was closed, we would crawl to the exit but still never idle for 15 mins straight without moving.


Also per OP, he chokes for 2-3 secs, that is a LONG time, you will get honked most of the time if you dont move for 3 secs when the light turns green.

Even if i needed to stay in the car for 15 mins because outside is 110 degrees here while waiting for someone, that still does not justify 3 secs delay. Our cars are automatic, it moves forward the moment you let go the brake.

I dont see it is realistic to wait for someone for 15 mins and WOT the moment he/she gets in...

We need OP to provide more Info....

You've clearly never been in a gridlock that doesn't move. I've been in those situations and even then I keep my car running period.

But that's besides the point - OP is asking if it is normal for the car to experience acceleration lag after the car has idled for that long - *regardless* of OPs reasoning for idling 15 minutes.

[oonowindoo]

Originally Posted by zazzau

You've clearly never been in a gridlock that doesn't move. I've been in those situations and even then I keep my car running period.

But that's besides the point - OP is asking if it is normal for the car to experience acceleration lag after the car has idled for that long - *regardless* of OPs reasoning for idling 15 minutes.

Nope i have not and i live in LA... so i guess it should not be a common issue.

The reason that not a lot of ppl would respond is what he is describing is so rare that it should not be an issue.