[LilHades]

I have a 2009 335i coupe. It seems everytime I accelerate quickly it goes into limp mode. I can still reach high speeds on highway if I slowly accelerate. But anytime I press hard on the gas it doesn’t have the torque like normal and instantly goes into limp mode. I’ve changed my Vanos solenoids and camshaft sensors, but that didn’t fix the issue. Only code right now is P0420 which I don’t think is causing the limp mode(relating to the Cat converter). But I’m thinking it could possibly be the oxygen sensor or maybe bad spark plugs but I’m not feeling any misfire. Has anyone experienced this?

[clegg]

Run a bottle of Techron in your fuel tank.

[lookalikehuuh]

Step 1, get a proper scan tool to read actual BMW codes. Sounds like the scanner you have now is a Generic OBDII since you have a "P" code. Generic OBDII readers can only access a super tiny amount of the codes that BMWs can set.

If you use MHD for tuning, you can read the codes using MHD.

Ideally you need to grab a log so we can see large amounts of data as you accelerate the car. Limp mode can be caused by tons of issues and blindly throwing parts at it won't do anything for you except waste your money for no reason. Once you have the log you can upload it to datazap.me and past a link here and we can then help you figure out if you have an issue with fuel, boost, timing, etc.

[lowrydr310]

Originally Posted by LilHades

I have a 2009 335i coupe. It seems everytime I accelerate quickly it goes into limp mode. I can still reach high speeds on highway if I slowly accelerate. But anytime I press hard on the gas it doesn’t have the torque like normal and instantly goes into limp mode. I’ve changed my Vanos solenoids and camshaft sensors, but that didn’t fix the issue. Only code right now is P0420 which I don’t think is causing the limp mode(relating to the Cat converter). But I’m thinking it could possibly be the oxygen sensor or maybe bad spark plugs but I’m not feeling any misfire. Has anyone experienced this?

Sounds like a broken vacuum line for your wastegate actuators.

[LilHades]

Originally Posted by lookalikehuuh

Step 1, get a proper scan tool to read actual BMW codes. Sounds like the scanner you have now is a Generic OBDII since you have a "P" code. Generic OBDII readers can only access a super tiny amount of the codes that BMWs can set.

If you use MHD for tuning, you can read the codes using MHD.

Ideally you need to grab a log so we can see large amounts of data as you accelerate the car. Limp mode can be caused by tons of issues and blindly throwing parts at it won't do anything for you except waste your money for no reason. Once you have the log you can upload it to datazap.me and past a link here and we can then help you figure out if you have an issue with fuel, boost, timing, etc.

I actually took it to a mechanic who had one and got a code saying the turbocharger Boost pressure low. Also a fuel pump code but I don’t have any symptoms of the fuel pump going out. Sorry I don’t have the actual BMW codes.

[LilHades]

Originally Posted by lowrydr310

Sounds like a broken vacuum line for your wastegate actuators.

You may be on to something, I have a code for turbocharger Boost pressure Low. But at a quick glance I don’t see any broken lines.

[Serf27]

It could be a number of things.
https://bmwtuning.co/bmw-n54-30ff-en...urbos%2C%20etc.

[lookalikehuuh]

Originally Posted by LilHades

I actually took it to a mechanic who had one and got a code saying the turbocharger Boost pressure low. Also a fuel pump code but I don’t have any symptoms of the fuel pump going out. Sorry I don’t have the actual BMW codes.

Yeah this makes sense, a log would tell us what the boost target is and what the actual boost you are hitting is. This could be due to a multitude of issues like a failed turbo, loose pipes, broken charge pipe, other leaks etc.

The fuel pump information is also logged (both low pressure and high pressure) so that would also help us direct you into what is causing the issue. Keep in mind that high pressure fuel pump is a common failure and can cause major issues if the pressure isn't building the way its expecting to.

[crosbyblue]

Originally Posted by LilHades

You may be on to something, I have a code for turbocharger Boost pressure Low. But at a quick glance I don’t see any broken lines.

I had this exact problem, what ended up happening was one of my little rubber vacuum lines slipped off the nipple(?) of my boost control solenoid. It was barely noticeable, I had to really search hard with my flashlight to see it off the connector, and it was only removed about 2-3 cm.

I ended up putting the line back on the solenoid and heated it up with a lighter & heat gun to shrink the line back on to where it should be. Haven't had any issues since.

[lowrydr310]

Originally Posted by crosbyblue

I had this exact problem, what ended up happening was one of my little rubber vacuum lines slipped off the nipple(?) of my boost control solenoid. It was barely noticeable, I had to really search hard with my flashlight to see it off the connector, and it was only removed about 2-3 cm.

I ended up putting the line back on the solenoid and heated it up with a lighter & heat gun to shrink the line back on to where it should be. Haven't had any issues since.

That's exactly what happened to me. I noticed the car didn't have as much low end torque but still no SES light or any other indication of a problem. Then when I accelerated onto a highway that's when I got the half engine light and really felt the lack of power, and corresponding 30FF code when reading with INPA.

I found an obvious split in the vacuum line that went from one of the canisters to the hard line that goes over the valve cover. I simply snipped it below the split with scissors and reattached which worked fine but I eventually replaced all the vacuum lines to avoid any future problems. Mine were in bad shape - extremely brittle with lots of fraying of the protective cloth covering.

Data logging is awesome for diagnosis but how do those of us without MHD go about doing that? I'll eventually buy it after I get some more maintenance items sorted out.