[TrippleG]

Hi guys, I have been autocrossing my e90 335i for about a whole season now, and in most of the courses that require you to stay in 2nd the turbo lag (or lack of power in low rpm) is really holding me back when I need the car to rotate, so it doesn't plow, but when the boost kicks in it seems to be too late. The ecu is chipped with a jb4 and I usually run map 5 or 2 I don't find much of a difference between them. Is there a map I could program that could help with this? Also I plan on upgrading my down pipes soon, if someone could recommend me a set that is affordable but would suit my needs I would appreciate that!

[Antetokounmpo]

VRSF downpipes, these will decrease lag slightly, a DCI may help, but not so much, inlets help more though. Otherwise not much you can do. What RPM are you talking here? When I autox I get down to maybe 2500, and I don't think there's much lag in second gear at 2500rpm running 18psi.

[335NJ]

Which JB4 are you using? G5 ISO?

And which firmware?

2nd gear in my car is like a damn on/off switch on the boost-o-meter.

[TrippleG]

I recently installed the jb4 so I believe its the G5 with recent firmware not 100% sure but i'm going to run a usb in my glove box for easy access to that.

I have a BMS DCI seems to be sucking a ton of hot air from the engine though.

The lag seems to be around 2k rpms the car seems to bog and take a few seconds then the boost kinda throws me forward, can be sideways if your not careful. I've had some issues with limp modes from the vanos solenoid's replaced the exhaust one and got 1 code from the intake vanos so far.

[sirdaft1]

Welcome to turboland! Not much you can do other than keep DWP (Default Wastegates Position) at 100 via JB4. Not sure how much that will help though.

[TrippleG]

How's the decrease in lag from upgrading diverter valves?

[TrippleG]

Originally Posted by sirdaft1

Welcome to turboland! Not much you can do other than keep DWP (Default Wastegates Position) at 100 via JB4. Not sure how much that will help though.

I've had terrible wastegate rattle so i'll have to give this a shot! Starting to consider something naturally aspirated... Or maybe doing a supercharger swap

[sirdaft1]

It's more of a function of the turbos. They really don't spool to full boost until 3200+ rpms. Until then you're really just waiting until those snails to spool.

[sirdaft1]

Originally Posted by TrippleG

I've had terrible wastegate rattle so i'll have to give this a shot! Starting to consider something naturally aspirated... Or maybe doing a supercharger swap

If you're having issues with WG rattle then you should drop DWP to 12. But that will give you boatloads of turbo lag (but really throaty exhaust since WG's are letting exhaust gases flow right through).

[TrippleG]

Could the faulty waste gates be causing the lag? Just throwing that out there

[jippii ensio]

Originally Posted by TrippleG

Could the faulty waste gates be causing the lag? Just throwing that out there

Yes

[TrippleG]

Might just replace them when I do the downpipes will I need to purchase 02 simulators with a cat delete?

[secretsquirrel]

It really sounds like you have a mechanical problem somewhere. I'd probably look at your boost solenoids and vaccuum lines.

[TrippleG]

I could take a video of WOT in 2nd?

[Antetokounmpo]

Originally Posted by TrippleG

I could take a video of WOT in 2nd?

Better yet take a log with jb4 in second gear so we can see the spool.

[mirkwo0dforest]

Sounds like me, I'm laggy as hell and get 1/2 engine every once in a while... low boost, let me know what you find out. I'm running JB4 map1, but i get the code throw sometimes on map 4, (stock+log)

[Antetokounmpo]

Originally Posted by mirkwo0dforest

Sounds like me, I'm laggy as hell and get 1/2 engine every once in a while... low boost, let me know what you find out. I'm running JB4 map1, but i get the code throw sometimes on map 4, (stock+log)

Take some logs and post them, we'll be able to see what's wrong.

[TrippleG]

Originally Posted by Heel Toe

Better yet take a log with jb4 in second gear so we can see the spool.

Sounds good when I get my cable ill take some log and post back here with the results!

[mirkwo0dforest]

Originally Posted by Heel Toe

Take some logs and post them, we'll be able to see what's wrong.

Here ya go...

[MachWon]

Set map 10 to 5k rpm when autocrossing, this sets the DWP to 100. I drive around town with DWP at 0 because of rattle but when I push my car I set it to 100.

[Antetokounmpo]

Originally Posted by mirkwo0dforest

Here ya go...

That is very slow. Do you have a 30ff code?

Also update your jb4 firmware to 31_4

[spxxx]

There's a boost leak or your turbos are probably on the way out... These cars have almost no turbo lag at medium levels of boost (which you'd want for autox) no need for more than 400wtq or so unless you're in super sticky tires.