[JoshApple]

I’m getting limp mode at or around 5K rpms or WOT on my 07 335i and I’m not exactly sure what’s causing it. I’m pulling codes 30FF and 29F3 Fuel pressure sensor. Am I getting limp mode because of one of these sensors? If so which one should I replace low pressure or high? It could also be a vacuum leak but I don’t see how that would cause limp mode right at 5k but I’m not sure. Any recommendations/insight would be greatly appreciated.

-Josh

[rawdog573]

Originally Posted by JoshApple

I’m getting limp mode at or around 5K rpms or WOT on my 07 335i and I’m not exactly sure what’s causing it. I’m pulling codes 30FF and 29F3 Fuel pressure sensor. Am I getting limp mode because of one of these sensors? If so which one should I replace low pressure or high? It could also be a vacuum leak but I don’t see how that would cause limp mode right at 5k but I’m not sure. Any recommendations/insight would be greatly appreciated.

-Josh

I had the same issue. I pretty sure my boost solenoids are bad. Can't afford new ones at the moment so I just plugged the wastegates to straight vacuum. Been goin a while
Now with no issues boosting 18psi

[JoshApple]

Originally Posted by rawdog573

I had the same issue. I pretty sure my boost solenoids are bad. Can't afford new ones at the moment so I just plugged the wastegates to straight vacuum. Been goin a while
Now with no issues boosting 18psi

How did you do that? How much are boost solenoids and is it a doable fix?

[rawdog573]

Originally Posted by JoshApple

How did you do that? How much are boost solenoids and is it a doable fix?

New solenoids are like $150 each. I unhooked the rear one and where the hose goes to the wastegates. Unhook you're canister you solenoid hose and basically make it canister to wastegate. Bypass the solenoid. It's not recommended to do because you can overboost. But it's just a tell fox until I get bills paid off and can afford new parts

[dpaul]

Excuse me but why the fuck is anyone talking about boost solenoids?

30FF is low boost which happens because the DME shut off the turbos because there is a fuel pressure problem.

29F3 indicates (I believe but look it up yourself) a problem with the low pressure fuel sensor. There is likely either a) problem with the sensor, b) problem with its wiring, c) problem with the fuel pump.

Log a few runs and see what the fuel pressure is doing.

[JoshApple]

Originally Posted by dpaul

Excuse me but why the fuck is anyone talking about boost solenoids?

30FF is low boost which happens because the DME shut off the turbos because there is a fuel pressure problem.

29F3 indicates (I believe but look it up yourself) a problem with the low pressure fuel sensor. There is likely either a) problem with the sensor, b) problem with its wiring, c) problem with the fuel pump.

Log a few runs and see what the fuel pressure is doing.

If it’s electrical what would I need to replace? Or should I just change out the low pressure sensor and see if that fixes it? I don’t have the tools to run logs I don’t think

[dpaul]

If you are going to work on the vehicle yourself, you need to make some modest investments in diagnostic tools. You were able to read codes but I don't know how that was done, conceivably you just went to autozone and had them do it. If you don't have a decent scanner, one that can read BMW specific codes and report freeze frame information, either get one or install the freely available BMW factor software (BMW Standard Tools - needs DCAN cable - get both at bimmergeeks.com). For logging, I like MHD, which many people use to flash parameter maps to the DME but can also log and also report error codes and is simple to use.

Judging by your first post, I'm guessing you haven't got much experience with the N54 engine. You've got two ways to go: do some reading to educate yourself and apply some critical thinking in your diagnosis to make sense of the codes and other information your diagnostic tools provide. Or just randomly replace parts - that gets really expensive really fast and is generally quite frustrating.

[JoshApple]

Originally Posted by dpaul

If you are going to work on the vehicle yourself, you need to make some modest investments in diagnostic tools. You were able to read codes but I don't know how that was done, conceivably you just went to autozone and had them do it. If you don't have a decent scanner, one that can read BMW specific codes and report freeze frame information, either get one or install the freely available BMW factor software (BMW Standard Tools - needs DCAN cable - get both at bimmergeeks.com). For logging, I like MHD, which many people use to flash parameter maps to the DME but can also log and also report error codes and is simple to use.

Judging by your first post, I'm guessing you haven't got much experience with the N54 engine. You've got two ways to go: do some reading to educate yourself and apply some critical thinking in your diagnosis to make sense of the codes and other information your diagnostic tools provide. Or just randomly replace parts - that gets really expensive really fast and is generally quite frustrating.

Actually, I used INPA and a dcan to scan and just got the car about a month ago. I’ve read hours of stuff about the issues I’m having and not the best answers. I did replace injectors myself and that fixed some of my issues and was thinking it would solve my limp mode issue, but I was Wrong. Now all I have left is a fuel pressure sensor code that is pretty vague. I already know how to replace the sensor but am holding off to see if that’s the issue before I buy things, that’s why I posted. I am planning to get MHD just not right this second.

[dpaul]

Originally Posted by JoshApple

I’m getting limp mode at or around 5K rpms or WOT on my 07 335i and I’m not exactly sure what’s causing it. I’m pulling codes 30FF and 29F3 Fuel pressure sensor. Am I getting limp mode because of one of these sensors? If so which one should I replace low pressure or high? It could also be a vacuum leak but I don’t see how that would cause limp mode right at 5k but I’m not sure. Any recommendations/insight would be greatly appreciated.

-Josh

Ok, perhaps you've done some reading. It's just pretty hard to tell from the discussion above. Why would you throw out the idea of a vacuum leak? How would a vacuum leak give you a fuel code? "Limp mode because of one of these sensors"? One of what sensors? - do you mean high and low fuel pressure sensors? High pressure sensor is a part of the HPFP and is not separately replaceable. In any case, 29F3 is a low pressure sensor code. Or did you mean one of the manifold absolute pressure sensors. That would be unlikely. A 30FF is a symptom, not a cause. The fact that you'd entertain the notion of replacing the boost solenoids to address this problem is stone crazy. Lastly, if you want someone to help you, help them first - give all relevant information about the vehicle, mods, tune, fuel, and recent service history

Your DME is giving you the clearest possible indication that you have a fuel problem. You could read the fuel pressures with INPA:
E90->engine->N54->live data->analog measurement blocks-> OBDII. You can only read the rail pressure directly but if you either activate the pump with INPA or just turn ignition but not engine on. Then the rail pressure is reflecting the pressure generated by the LPFP - should be steady and well above 50psi, ideally 65-72. You can also start the engine and verify rail pressure higher than 600 psi, reflecting HPFP operation. In german rail pressure = Kraftstoffdruck or raildruck and values may be in kPa, not psi.

Or you can spend $100 on MHD and get a graph of high and low pressure values over time while operating the car in real world conditions. If you are going to randomly replace stuff, the low pressure fuel sensor is the obvious choice. Best of luck