N20. Turbo-lag or flat spot?

[Pondy]

Hello fellow Z4 peoples,

I took my "new" car for a quick run today; first time really since purchase. The new brakes need some serious bedding-in!

It's an 18i N20 (156hp), 25,800 miles. I noticed there is a flat spot from about 1500rpm to probably 1800rpm. It pulls fine after that and there were no noises, or smoke. Is it turbo-lag, or something I should investigate?

It is having an oil change tomorrow and is due to be chipped next week, so want to make sure all is good before upping the boost. If it is turbo lag I'm concerned a re-map may make it more noticeable and if something else I ain't gonna get it done yet.

Ta
Pond

 

[Smartbear]

Hello fellow Z4 peoples,

I took my "new" car for a quick run today; first time really since purchase. The new brakes need some serious bedding-in!

It's an 18i N20 (156hp), 25,800 miles. I noticed there is a flat spot from about 1500rpm to probably 1800rpm. It pulls fine after that and there were no noises, or smoke. Is it turbo-lag, or something I should investigate?

It is having an oil change tomorrow and is due to be chipped next week, so want to make sure all is good before upping the boost. If it is turbo lag I'm concerned a re-map may make it more noticeable and if something else I ain't gonna get it done yet.

Ta
Pond

The twin scroll turbo doesn’t really suffer from flat spots, lag is minimal as well. Does your remapper carry out a “before” test on a dyno to check all is well before tweaking?
Rob

 

[Pondy]

Does your remapper carry out a “before” test on a dyno to check all is well before tweaking?
Rob

Nope. It's a man with a van and a laptop

I am now starting to think it might be my imagination, or just no power at those revs! I have been driving new Tdiesels for so long, I break out in a sweat when the rev counter goes over 1500.

 

[Pondy]

Does your remapper carry out a “before” test on a dyno to check all is well before tweaking?
Rob

Nope. It's a man with a van and a laptop

I am now starting to think it might be my imagination, or just no power at those revs! I have been driving new Tdiesels for so long, I break out in a sweat when the rev counter goes over 1500.

 

[Pondy]

oops double post.

 

[Nictrix]

Is it possibly the weird feeling you get while changing gears especially first to second from the CDV if its still fitted?

 

[Pondy]

Is it possibly the weird feeling you get while changing gears especially first to second from the CDV if its still fitted?

I don't know what a CDV is!

It's under acceleration; it's more a "hesitation" than a "lag".

 

[Nictrix]

Is it possibly the weird feeling you get while changing gears especially first to second from the CDV if its still fitted?

I don't know what a CDV is!

It's under acceleration; it's more a "hesitation" than a "lag".

The CDV is the clutch delay valve and basically slows the fluid travelling through the clutch hose.
Going from 1st to 2nd it can feel like a hesitation and if you dont get the change right can lead to a bit of kangarooing.

 

[Pondy]

Going from 1st to 2nd it can feel like a hesitation and if you dont get the change right can lead to a bit of kangarooing.

I have been driving manual gearboxes for 36 years; so could be

 

[flybobbie]

Get oil changed then check it.
Not Z4 but my Berlingo diesel i put in some cheap "turbo diesel" oil 20-50.
What a mistake, the engine seemed to lose power. I wondered if it was dragging the turbo down.
So refilled with Mobil 1, all working great now.

 

[True-Blue]

I wouldn’t be at all surprised if it’s the impact of the mapping effectively ‘strangling’ a 240BHP+ engine down to 156BHP

Hard to say as I’ve never driven 18i personally :?

 

[Pondy]

Hard to say as I’ve never driven 18i personally :?

Why would you?

 

[Pondy]

I got emailed some BMW technical info from a forum member the other day (shall remain nameless but has a dubious taste in pond safety paraphonalia).

All the info on the N20 engine referred to it having an output of 240hp. There was no mention of 156, or 184!

 

[Smartbear]

I got emailed some BMW technical info from a forum member the other day (shall remain nameless but has a dubious taste in pond safety paraphonalia).

All the info on the N20 engine referred to it having an output of 240hp. There was no mention of 156, or 184!

That’s the lesser spotted 28i variant
Rob

 

[Pondy]

That’s the lesser spotted 28i variant
Rob

Were your ears burning Robert?

 

[Ed.Straker]

https://www.evolveautomotive.com/evolve-ecu-remap-performance-upgrade-and-evolve-r-bmw-e89-z4-18i.html

Looks based on one dyno run only that the gelding of the 18i unit causes some strange low end torque hiccup..

 

[Pondy]

https://www.evolveautomotive.com/evolve-ecu-remap-performance-upgrade-and-evolve-r-bmw-e89-z4-18i.html
Looks based on one dyno run only that the gelding of the 18i unit causes some strange low end torque hiccup..

That is exactly the revs the problem is! I shall be getting my re-map and asking BMW to pay as they caused the issue in the first place.

Who knows: maybe it could be the first recall in history to increase power and torque

 

[Ed.Straker]

https://www.evolveautomotive.com/evolve-ecu-remap-performance-upgrade-and-evolve-r-bmw-e89-z4-18i.html
Looks based on one dyno run only that the gelding of the 18i unit causes some strange low end torque hiccup..

That is exactly the revs the problem is! I shall be getting my re-map and asking BMW to pay as they caused the issue in the first place.

Who knows: maybe it could be the first recall in history to increase power and torque

Maybe you could ask them to re-design your 326m wheels at the same time?

Snowballs and hell spring to mind.

Pity you’re not getting a dyno based setup...it’s always interesting to see the changes?

I see on a separate thread you intend to buy an Audi, so pondered (nice pun) why you are ‘upgrading’ the Zed?

 

[Pondy]

I see on a separate thread you intend to buy an Audi, so pondered (nice pun) why you are ‘upgrading’ the Zed?

The Z4 is the wife's. The Audi will be mine.

 

[Ed.Straker]

Aha sounds like a very loving relationship