[Missionpoole]

Long story short, picked up an auto 2008 e92 335i about a week ago with 75,000~ on it. Of course no lights when I bought it, and now it’s been nothing but problems, I’m lit up like a Christmas tree. I’ve been reading a lot on this forum (thanks everyone) and learning as much as I can. My experience is with Japanese imports, so this is my first BMW experience… learning the nuances 😂

It’s got a rough idle, and will stall out if I don’t give it some gas on a cold start. When warm, it’ll crank up and idle but still rough. It actually feels like it’s got okay power when driving it, and there are no major hiccups or jolts under load. I’d say it runs smoother in boost at 45mph than it does just sitting idle. There was one instance where I got a little higher into boost and it threw it into limp mode. After sitting for a day and cranking back up, limp was gone.

I did find a vacuum leak on the nipple of one of the vacuum tanks, so that’s at least one problem identified, but it’s definitely a minor leak and I don’t imagine it’s causing all of the codes below.

Anyways, I hooked up Carly to get a diag and here are the codes:

0029DC - cyl injection cutout

0029E1 - mixture control 2

002AAF - fuel pump plausibility

002DED - closed-circuit current violation

BMW, naturally, wants a kidney to diag and repair the problems, so I guess I’m getting my hands dirty with a German car after growing up on Mazda 😂🤣

They mentioned to start with the high/low fuel pressure sensors, repair the vacuum leak at the tank, and reassess, so that’s my current plan. Carly is saying that code 0029DC is a Charge Air Temp sensor, but I am not seeing one on the car. Does it mean a MAP sensor?

Any input, ideas, etc., very much appreciated.

Thanks in advance, and even though this has been a shaky intro to BMW ownership, I’m having fun with it.

[Missionpoole]

Update: threw some Techron in today to see if maybe it’s a stuck injector or some other grimy part of the fuel system. Drove it around a bit more while monitoring MHD for rail pressure. It went back into limp mode after driving around a bit mostly out of boost. When it went into limp mode I got a new code: 29F2, fuel high pressure system, and the rail pressure reading dropped to 50 and stuck there (unsure yet if this is just by design of limp mode or because my hpfp or rail sensor is bad).

Any thoughts on where I should start on the replacing? Sensors first? Cheers

[Missionpoole]

Update: starting to think it could be the HPFP? Cleared codes and drove it a bit but went back into limp with 29F2. Definitely has all symptoms of a failed HPFP. Waiting on parts to come in but will update if this solves my problem. Replacing both high/low pressure sensors, the vacuum tank leak, and if that doesn’t do it, the hpfp.

[Missionpoole]

Just popping in to update and vent a bit. Car is still apart in the garage and I'm feeling more and more frustrated. Replaced low pressure sensor with feed line, fixed up all known vacuum leaks, replaced throttle body gasket and cleaned the carbon off the TB....

Next, replacing intake, chargepipe, HPFP, rail sensor, oil filter housing gasket, valve cover gasket, plugs, coils and pulling the intake manifold to inspect valves and replace gaskets. That's it for now? I think. Also on the list that needs replacement is the oil pan gasket, all shocks/struts are blown, front thrust arms are blown, rear brake pads are on their last leg, needs tires lol.

This dealer definitely misled me and I definitely am not excited to have a new daily that immediately goes down for weeks and costs $6k+ to get healthy again. All at only 75,000 miles lol. Crazy my luck.

If you're reading this before buying your next car, get a better mechanic inspection than I did before paying 😂

[Missionpoole]

Oh- and if there's any other known common oil leaks, let me know. I already have most of the top side apart anyways. My entire block is caked in oil. Can't tell where it's coming from because it's everywhere. What I do know is that the OFHG is bad, and the oil filler cap seems to be leaking too. Replacing valve cover gasket while I've got it apart just in case.

[suspect]

You can log the hpfp (fuel rail pressure) and it should be around 1500-2200 psi at WOT. If below at at WOT then indicates potential hpfp issue. To check lpfp you will probably need something like inpa. The lpfp pressure should be between 50-75 psi.

[CarAbuser]

You're pretty much doing the 335i / E9x starter kit.

You've got a 15yr old car that's been owned by someone that doesn't care for maintenance. It's pretty standard to overhaul the suspension at that point. Shocks, springs and bushings all-round. That's been the same story for any car I've ever owned.

You then have to deal with the pit-falls of an N54. If on original HPFP and injectors then you should expect to replace those. Valve cover and OFHG are also expected and you should refresh the aux belt, tensioner and pulleys if there has been an oil leak on the front of the engine.

It's the dream car for someone who does their own work and likes tuning. Not so much for someone who wants a hassle-free work horse.

[jadams161]

sell it to me for cheap

[C4maro]

replace all the rubber vacuum lines on the engine whether you've found a leak or not.

[Missionpoole]

Originally Posted by C4maro

replace all the rubber vacuum lines on the engine whether you've found a leak or not.

I appreciate this reminder. Bought some new verocious lines so I’ll swap them all out.

[E93Seattle (Racerbruce)]

Originally Posted by Missionpoole

I appreciate this reminder. Bought some new verocious lines so I’ll swap them all out.

good move - verocious lines are very high quality; i'm appx 2/3rds done replacing mine.

[Missionpoole]

Originally Posted by E93Seattle (Racerbruce)

good move - verocious lines are very high quality; i'm appx 2/3rds done replacing mine.

I just did everything but the line that runs from the T to the rear turbo because I couldn't fit my hand back there 😂

[Missionpoole]

Just an update.

Replaced a ton of stuff last weekend and cleared almost all codes. I believe my fueling issue was the HPFP but I also replaced both sensors. LPFP is showing strong now.

Lingering problems is a mixture control 2 code and cyl 5 misfire that comes and goes. Thinking it’s probably an injector. My bank 1 injectors are index 12, bank 2 are index 9. Replacing bank 2 with index 12 then will update again if all codes are gone.

[Aode06]

Replace the HIGH PRESSURE FUEL PUMP its done for.
Plenty on ebay cheap
https://www.ebay.com/itm/185946703803
Example

[Missionpoole]

Originally Posted by Aode06

Replace the HIGH PRESSURE FUEL PUMP its done for.
Plenty on ebay cheap
https://www.ebay.com/itm/185946703803
Example

Yes indeed it was! That solved the fueling problems for the most part.

[AWD Addict]

Plugs all clean with no fuel smell?

If you haven't done the OPG yet, consider doing your rod bearings. There's a correlation between poorly cared for n54 and n55s and bad bearings. If you're already under there at the oil pan, it's pretty cheap money to replace them.

[Missionpoole]

Originally Posted by AWD Addict

Plugs all clean with no fuel smell?

If you haven't done the OPG yet, consider doing your rod bearings. There's a correlation between poorly cared for n54 and n55s and bad bearings. If you're already under there at the oil pan, it's pretty cheap money to replace them.

I appreciate the tip, I haven’t done OPG but it sounds like I will do rod bearings while I’m in there. I don’t know the first thing about replacing them, but I’ll check into it. Thanks again.

[Jaronbwall]

For a car with only 75k miles that's shocking. Some people love doing zero maintenance and driving there vehicles into the ground. A lot of wealthy owners just trade them in for the next new hot car (keeping up with the Joneses). One of my best friends claims he's a "car guy". He upgraded a new jeep and a used truck with bolt-on's and still ran both vehicles into the ground. Both were broken down a few times and sold/traded-in for a big loss.

You really have to love the N54 to play this game. I feel like an old person reading these forums yet I'm only 36. Without the DIY support, YouTube videos, and tutorials I would have sold my 335i years ago. Every maintenance issue, upgrade, or repair can be thousands $$$ at an Indy or stealership.