[jeddo45]

Hi all

So this past week I decided to drop the MHD stage 1 tune on my 335i. I don't know why I waited so long but I have been very pleased with the results.

My issue is when I hit 7k RPM's the engine goes into limp mode. When this happens it seems that the turbo boosts at about half power. My question is what needs to be adjusted in order to prevent the limp mode? I have tried searching the forums and have come up short of a solid answer (unless I totally missed it).

Thanks in advance.

[lordbmw]

Originally Posted by jeddo45

Hi all

So this past week I decided to drop the MHD stage 1 tune on my 335i. I don't know why I waited so long but I have been very pleased with the results.

My issue is when I hit 7k RPM's the engine goes into limp mode. When this happens it seems that the turbo boosts at about half power. My question is what needs to be adjusted in order to prevent the limp mode? I have tried searching the forums and have come up short of a solid answer (unless I totally missed it).

Thanks in advance.

I'm using Stage 1 and my car doesn't go into limp mode.

You must have something wrong with your car.

[BSM n54iS]

You mean when you hit the redline???

[AZDesertBMW]

I would see what codes are stored. I've read of mhd uncovering when a car has bad coil plug(s).

[Slow335xi]

I've heard this can be a sign of the turbos going out, have you had the recall done? Pull the codes and post them so we can get a better idea of what's happening.

[jeddo45]

Originally Posted by AZDesertBMW

I would see what codes are stored. I've read of mhd uncovering when a car has bad coil plug(s).

So I did pull codes yesterday and it was something along the lines of "low boost pressure." I don't remember verbatim. I'll pull codes again and get specifics.

[jeddo45]

Originally Posted by BdSM n54iS

You mean when you hit the redline???

Yes when I hit the redline. Anything under it, no limp mode.

[AZDesertBMW]

Originally Posted by jeddo45

So I did pull codes yesterday and it was something along the lines of "low boost pressure." I don't remember verbatim. I'll pull codes again and get specifics.

Then I would think your coils are ok as that would normally give a misfire code. Boost leak, bad diverted valve, maybe? Hopefully there are people following who know more.

[BeastMode335i]

Well considering that 7k is past redline, just stay clear of that.. You're not hitting full boost past 6200 rpms anyways, so I'd suggest shifting closer to 6k RPM's..

[6ixSpd]

Originally Posted by BeastMode335i

Well considering that 7k is past redline, just stay clear of that.. You're not hitting full boost past 6200 rpms anyways, so I'd suggest shifting closer to 6k RPM's..

7K is redline. OP's car seems to have a boost leak as he's saying the code referred to low boost pressure.

[Mr. Tasty]

Maybe a bad charge pipe? Crack expands on increased pressure?

[racermp]

i'm stock on stage 1+ v.24 MHD and test tunes, no issues here. boost leaks suk

[jeddo45]

Here is an update with screenshots from MHD code reader:

Screenshot 1:


Screenshot 2:

[The335iGuy]

Originally Posted by jeddo45

Here is an update with screenshots from MHD code reader:

Screenshot 1:


Screenshot 2:

When I had that code on mine it was because the vacuum lines were cracked. Could also be a charge pipe, or your turbos. I'd start by visually inspecting the vacuum lines, charge pipes, and the other hoses they connect to. Maybe just replace the vacuum lines if they're old and you can DIY.

[jeddo45]

Originally Posted by The335iGuy

When I had that code on mine it was because the vacuum lines were cracked. Could also be a charge pipe, or your turbos. I'd start by visually inspecting the vacuum lines, charge pipes, and the other hoses they connect to. Maybe just replace the vacuum lines if they're old and you can DIY.

I'm out of town for work but that will be something I'll look into. I guess my question is why would it be going into limp mode if at the higher RPMs the turbo is not boosting at full power?

[The335iGuy]

Originally Posted by jeddo45

I'm out of town for work but that will be something I'll look into. I guess my question is why would it be going into limp mode if at the higher RPMs the turbo is not boosting at full power?

Maybe the car just doesn't shut it down and go into limp mode until then? I wouldn't think losing boost due to a vacuum leak would be something that makes the car absolutely shuts down as shown as it happens. Does it feel like you're losing anything in the boost or power you get before you get the limp mode?

Mine was overall less powerful and if I accelerated hard I'd eventually get that code and it ended up being a vacuum leak so I'd start there but I've heard it can also be diverter valves or the turbos.

[jeddo45]

Originally Posted by The335iGuy

Maybe the car just doesn't shut it down and go into limp mode until then? I wouldn't think losing boost due to a vacuum leak would be something that makes the car absolutely shuts down as shown as it happens. Does it feel like you're losing anything in the boost or power you get before you get the limp mode?

Mine was overall less powerful and if I accelerated hard I'd eventually get that code and it ended up being a vacuum leak so I'd start there but I've heard it can also be diverter valves or the turbos.

So let me kind of walk you through it as best as possible.

First off, when I am driving very conservatively and the turbos are just barely spooling, there is a noise that sounds like a high pitch whistle. It isn't super loud but it's definitely there. Something sounds off (and this noise has come on and off in the past).

Then when I drive it in regular drive (not sports mode or manual) and I get to the higher RPM's limp mode is activated. At this point it feels like the turbos go down to about half power.

My vacuum lines *LOOK* like they are fine. My gut says it's the actual turbos but I'm definitely open to any other possible options.

[BashShah]

Jeddo45,

Your Car is 10 Years Old.
things will Break.

I am not modded at all and what I discovered I was like How the hell did this Happen.

I had a 30FF recently at only Half Throttle not WOT.
I don't drive Rash.....but I do Drive Fast.

ok, after not seeing any of lines have any issue visibly...I said, what the Hell.
just to be sure lets just replace all the Vacuum Lines.

and I had a Leak behind the Rear Turbo actuator and it was something that can not be seen.....I just felt it after removing the Vac line.
The Braided rubber Vac Lines look ok visibly but they don't show what has been damaged from the inside.

so after removing the lines....feel them by Pressing them everywhere.
I found a Cavity under the perfect looking Braided stuff.

Now bought Silicone High Temp 3.5mm and I am back on the road.....ohh....and full WOT tooo.

The Best and cheapest I could find:
http://www.verociousmotorsports.com/...ld-by-the-Foot
you will need: 10 feet.

DIY coming up soon.
good luck

[BeastMode335i]

Originally Posted by 6ixSpd

7K is redline. OP's car seems to have a boost leak as he's saying the code referred to low boost pressure.

I know our gauge cluster says 7000 rpms is redline, but what I meant was, with our torque curve falling on it's face prior to 7k, shifting at 7k is pointless.. Especially since once the next gear is producing more torque then the current gear, it's time to shift anyways..

[unrealii]

Originally Posted by DarkNemesis

Jeddo45,

Your Car is 10 Years Old.
things will Break.
...

Looking forward to the DIY

I have a similar issue as OP but that is only if I do a 3rd gear run uphill which the car has to hold boost longer.

[jeddo45]

Originally Posted by DarkNemesis

Jeddo45,

Your Car is 10 Years Old.
things will Break.

I am not modded at all and what I discovered I was like How the hell did this Happen.

I had a 30FF recently at only Half Throttle not WOT.
I don't drive Rash.....but I do Drive Fast.

ok, after not seeing any of lines have any issue visibly...I said, what the Hell.
just to be sure lets just replace all the Vacuum Lines.

and I had a Leak behind the Rear Turbo actuator and it was something that can not be seen.....I just felt it after removing the Vac line.
The Braided rubber Vac Lines look ok visibly but they don't show what has been damaged from the inside.

so after removing the lines....feel them by Pressing them everywhere.
I found a Cavity under the perfect looking Braided stuff.

Now bought Silicone High Temp 3.5mm and I am back on the road.....ohh....and full WOT tooo.

The Best and cheapest I could find:
http://www.verociousmotorsports.com/...ld-by-the-Foot
you will need: 10 feet.

DIY coming up soon.
good luck

This definitely helps. I just haven't had time to really take things apart. Work has been extremely busy.

I'll start with thoroughly inspecting the vacuum lines. I hope this will fix my little issue and I'll be back at normal functions.

[vrracing]

There is already a great thread on replacing the vacuum lines. Includes color coded drawings and folks have provided tips on getting to the annoyingly unreachables.

Vacuum Line Replacement

I pulled the one from the intake to the diverters this weekend when I walnut blasted and found it had three splits under that cute braided cover. The shop I'd bought the car from took it to the local BMW dealership because it would go into limp mode for no apparent reason. It took BMW several days to figure out it was a bad vacuum line. So they replaced the one bad segment.



Remember that the vacuum lines were spec'd to survive to the last day of the warranty period and not a second more. For the $20 it will cost you for the silicone line it would be imprudent to not spend a couple of hours and replace it all.

Oh, and you will have to replace or rebuild the turbos. Hopefully not today!



Jim