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Trouble with P0171/P0174, and now P0460??

34K views 37 replies 18 participants last post by  love2drive330CI 
#1 ·
Hi all. Long time lurker and learned soooo much from you guys so thank you!!

Today I need some advice with these codes I've been getting.

Background: I have a (May) 2004 330i. I pulled the intake to locate a leak and fixed it (oil filter housing gasket). I also replaced the manifold and throttle body gasket along with replacing broken or brittle vacuum pipes since it was apart. This was about a year ago. Since putting it back together I have gotten P0171 (System too Lean (Bank 1)) and P0174 (System too Lean (Bank 2)) codes intermittently. Seemed to happen more when it was cold but not always, however that was the only pattern I could discern. The codes started with reading as two of each then went to two of P0171 and one P0174. I figured it was air in the line since I popped the fuel line off when doing all that work, but then more recently was thinking it was the fuel filter and need to get to it (48k miles now).

Yesterday I got the three codes again, though this time when I read the codes I also had a P0460 (Fuel Level Sensor Circuit Malfunction).

Initial searching brought me to TKC's thread where he replaced the sender, pump, and filter. http://forum.e46fanatics.com/showthread.php?t=592414

I haven't had a chance to pull it apart again to make sure the elbows were tight and no new holes (I had to get a new elbow off the TB because I butchered the old one to get it off) as I've found that and bad precat O2 sensors can cause the 171/174 codes. But now with this new code I'm getting a little worried. I need this car for work (unfortunately I do some field service in it) so pulling it apart has been backseated. It can be sluggish at times but it usually only lasts a second or two. And the SES comes one usually after driving and I'm stopped at a light.

Does this sound like I need to replace the sender, pump, and filter? Could the codes be coming from something I did in the engine?

I have INPA on my laptop and can see misc levels from the engine and I noticed the precat O2 sensors were only at 49%-50% while the postcats were 100%. This was with the engine temp at normal/middle of the gauge.

I'm unfortunately on a budget and at times have limited time to work on it so any help, suggestions, advice, BS to narrow it down is so gratefully appreciated!

Also if I'm not in the right forum I'm truly sorry. I wasn't sure if this was the right one or the DIYor even the Tuning and Tech/Driveline was the right place.

thanks!
 
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#3 ·
check the DISA intake for leaks!! Use combustion chmaber cleaner and spray around DISA inlet to manifold.... check for changes to engine RPM... had same issue (except for last code), and problem was with DISA seal and flap inside DISA broken. Flap repaired and DISA reinstalled and no issues since.
 
#4 ·
I wouldn't replace the fuel level sensor and sending unit yet. First just change the fuel filter first and see if that does it. I think if the filter is clogged you get some of the same symptoms as when the sending unit isn't working right.
As for the 0174 and 0171 codes, as the poster above stated it could be a small leak in an intake hose. Easy to rule out with some brake cleaner before you go changing the O2 sensors out.
 
#8 ·
Like grandsrus, same codes and MAF sensor. If they keep coming up you need to replace the sensor. Make sure you take care of it quick, you're not doing your engine any favors by running lean.

no, thats not always the case. Quite a few other things that it can be.
 
#7 · (Edited)
@kamagazi: In INPA the precats are at 1.5v and the postcats are .67v - .70v. Though when I was looking at them they actually dipped a little bit. The Bank1 postcat sensor dropped to .11v but then went back up to .67v. If they were constant that would be the sensor, right? This means more the fuel is not getting there? The percentage I noticed before are the 'lambda sensor heating' readings. Both precats are 46% and postcats are 99%. I also checked the error memory and it was listing "2882 mixture preparation bank1", saying "signal or value above threshold" and giving the P-code P0171. In the 'detailed' list it shows "average value bank1 5.86%" but unsure which value that really is in INPA.

@everyone: I sprayed some CRC brake cleaner around the DISA and the elbows but no change in RPM. I only did a quick spray of it in those areas but could def smell it so not sure if I it was enough to find an intake leak. I sprayed some at the front air intake but it didn't seem to change any so I might not be spraying enough. As far as the MAF, I don't have MAF cleaner but looking at it it is very shiny so could it still be dirty even if it looks clean and shiny? I know oil from the K&N filter can mess with it but it's looking clean. And could I use TB cleaner and be safe? I know they make MAF cleaner for a reason but in ATL it's snowing and gonna be a PITA to get any probably for the next 24hrs.

damn... did a search on that 2882 code and found this thread over at bimmerfest. My separator was replaced before I bought the car (it looks new and was told it was replaced) but maybe this is it or I have a leak somewhere in those lines? I tried opening the cap while running and there's a small vacuum and the idle does change a little bit when the cap is put on and taken off, is that normal? There's also a little 'sucking' sound from around the separator so maybe I didn't plug something in, again? Pulling this intake again is gonna ssuuuck lol

again, thank you everyone! this is really helping me get to the bottom of this! :thumbsup:

addition: btw, should the DISA make noises like in this video? I don't think mine are as loud but sound similar.

http://s12.photobucket.com/albums/a208/solidjake/?action=view&current=MOV02505.flv
 
#10 ·
#9 · (Edited)
a small side question to all of this... been reading more as I gave up tearing out the intake for the night. What is 'multiplier adaption' and what would be decent values? Some of the screens i printed shows a multiplier of like 12%, but the additive is like around -1.0 to 1.0. It seems to deal with mixture trim but with taht i'm kinda lost.

thanks :confused:

add: btw, i'm pulling the intake to make sure the stupid CCV is ok, along with its pipes, and to maybe replace this leaking oil line (not too bad just on the line tho).
 
#13 ·
I have been getting the same 2 codes 171/174 and cannot narrow down the cause, i have checked for vaccum leaks and eveything is good! However mine is always affected by weather, when it gets below 30 for a period of time, ill get the check engine light, as soon as its above thirty no code at all, the car seems to run better when the weather is warmer. I know i "run" better when the weather is warmer!!

I do get the rough idel when im at a stop light or stop sign, no stalling. the car runs great! Still has great power... This has been driving me nuts, so i know how your feeling!!!
 
#15 ·
ok... I've concluded the DISA and CCV are ok but there might be an air leak between the DISA and intake manifold along with that pipe that was becoming brittle. Might be getting the pipe tomorrow from the dealer (only $2 more than Tischer) and then finding some silicone sealant to bead around the DISA (why don't they just make a damn gasket for this thing??). Hopefully Friday I'll have it running and can test more then. This time I'll use INPA and get the BMW codes instead of these stupid P-codes.
 
#17 ·
I replaced the pipe but didn't seal around the DISA opening. Currently, no light but had a P0171 code listed in INPA, and this is after the pipe was replaced and adaptations cleared.

One thing the car did yesterday was misfire or stutter. It did this after driving around 50mph for a bit and then stopping at a light. It kicked pretty hard to the passenger side, but it seems it was just once and guessing on one cylinder. It was really quick. Drove a bit more since and never did more of this. But there was no code from this.

I've gone through this site and I think my MAF is ok along with my O2 sensors, so that leaves another leak somewhere in the intake (maybe manifold gasket as I did replace that the first time I broke it down) and/or dirty/clogged fuel filter. I used INPA to activate the DISA and I hear it activating but will have to pull it and activate it while out to make sure it moves.

I'm probably going to pull the intake again and make sure the manifold gasket is ok and see about getting a fuel filter. INPA shows the pressure is ok but never know.

I need to find the meaning to some of the readings in INPA because the multiplier adaptation (i'm pretty sure it is the long-term fuel trim) is still high, though not as high as before, so I'm not sure if I have something else going on. The levels seem to rise only while driving and fall while idle or driving like grandma. I could really use another 330i E46 to get good readings off of to compare with. It doesn't really feel it's running right, like a little sluggish at accelerating and mileage is a little low still. But the pipe was a definite issue.
 
#20 ·
Now that the weather is warmer...50F i havn't had any codes, but i still notice a little rough idle at stop signs and Stop Lights.

I have carsoft which does do live readings of different sensors, O2 and whatnot, i can get you my readings and see how they compare?

EDIT: My bro has a 03 330i, his next day off i may sway MAF's with him to see if anything changes
 
#18 ·
hello fellow e46'ers
my prob's are the same as all here. i too am getting double p0171&74 codes. I have taken off, checked, and replaced just about all under the hood, except taking off the intake. did all the ccv pipes, then took off and clean the maf and the disa. after putting disa back on i got the loud hissing noise like envoid. has anyone narrowed dwn the root cause of the two codes and now can you tell me why they double up. so lost any help or guidance will help and thanks in advance
 
#21 ·
@cdrshm: A friend of mine has an E90 that his girlfriend almost ran dry and was misfiring and running horribly so helped reset adaptations for him and at the same time checked to see how things worked with his N56 (love how the turbos sounded when they spun up). It updates much quicker but runs similar, though some things didn't jump around as much so thinking there is still a small intake leak. However, I haven't had a chance to check things on mine today. If you can get readings from your brother, I'd appreciate it but don't want you to go out of your way or anything. :)

I came across this thread from here in fact where everyone was saying the cold start stalls was the VANOS but for the poster it was the fuel filter. I'm feeling a light rough idle but not sure where from so wondering about both those now (could just be paranoia).

From that thread I also found that you can take 8" of electrical tape, cut it in half, and rap both strips around the DISA's gasket area to build up the seal. I was out today so thinking of trying this tomorrow along with testing to see if the flap actually moves when activated (INPA can do it while the engine isn't running).

@one2si: These lean codes seem to be created by almost a dozen different things... an intake leak (from CCV or its pipes, manifold gasket, intake elbows, or so many other different places), fuel pump (bad regulator or just clogged), VANOS seals, dirty or bad injectors or gaskets, bad oil dipstick gasket (part of CCV), cam sensor, O2 sensors (pre- and post-cat can fail without throwing codes), and even a bad DME. I think there are a few more I'm forgetting, too. It's almost a crap-shoot.

For the codes being tripped twice, I can't figure that one out unless its the amount that sets the SES light; If there's a large leak into both banks then I could see both being tripped at the same time. Though, I'm thinking if the leak is before the individual banks then both are tripped, and if a leak is on/from something that is connected to an individual bank then one is tripped more than the other or solely. The pipe that went bad for me this time was connected indirectly to both banks but was closest to bank1 and I had more bank1 codes than bank2. This is really only a theory and haven't tested it so take it with a grain of salt. ;) If you are hearing 'air' after doing all that work then double-check the connections for the CCV and make sure the pipes are snug in their ports. Also double-check your intake elbows are seated right, have no new cuts/holes, and their o-rings are snug. At least that is what I would start at.

As for the noise I heard, I haven't checked for it today though I will try tomorrow. Might also try more brake cleaner around the engine to see if anything changes, but I haven't had a code since replacing the pipe (well, minus that one that was right after).
 
#22 ·
Checked for the 'air' sounds and is less. I'm thinking the intake manifold itself is somewhat noisy and can sound like something is letting air in. Now i'm wishing I was around more of these engines with leaking intakes lol

oh and still no SES light but need to check for codes with INPA still.
 
#23 ·
I just wanted to add my story to this very helpful thread, to help keep the info together. My wife***8217;s ***8217;03 325i (123,000 miles) had a check engine light last week. I took it to a local guy to have the code read. The only code stored was P0174 (Lean on Bank 2). He cleared the code and suggested investigating the 2 boots between the MAF and intake, since it***8217;s a common problem. I couldn***8217;t find a thing wrong with them visually. I also sprayed starting fluid in all the suspect places looking for a leak and found nothing.

After finding this thread, and others like it, I decided to just go ahead and dig into it, in lieu of having it smoke tested. Here***8217;s what I ended up doing:

  • Replaced upper and lower boots from MAF to intake.
  • Cleaned MAF with CRC MAF Cleaner.
  • Removed/Cleaned DISA with CRC Throttle Body Cleaner.
  • Removed/Cleaned ICV with CRC Throttle Body Cleaner.
  • Replaced fuel filter.
  • Replaced both ends of vacuum line that runs from fuel filter regulator to F connector on lower MAF boot.

Let me tell you, I had a few choice words for the hose clamps on the lower boot, where it connects to the intake and ICV. I ended up going to town to get a flexible spinner handle and a flexible ¼***8221; extension, after I struggled with it for a couple hours. Even with the flexible tools, it***8217;s still a pain. Anyway, I found a small slit on the backside of the branch of hose that goes to the ICV. It is probably 1/8***8221; long and I***8217;m not certain it pierces the hose entirely, but it probably does and was probably part of the problem.

The MAF looked clean, but I cleaned it anyway.

The DISA was fairly clean and intact. There is a small amount of play in the rotation of the flap, but none in the pin that holds it in. I had the CVV system replaced at the end of last summer, so the tech that did that probably cleaned the DISA then. The gasket looked fine and I didn***8217;t add to it with RTV, tape or anything when I put back in. Since it had some play in it, I***8217;m going to replace it soon anyway, so I figured a leaking DISA seal would be an excuse to replace it now. But it doesn***8217;t appear to be leaking.

The ICV was gummed up pretty badly and not moving freely. I***8217;m sure this was the first time it has been out. It cleaned up nicely though and is free now.

I read a few posts here that suggested the fuel filter, or injectors, could be the cause of these codes and since it had never been replaced, I decided to pick one up when I got the boots. While I don***8217;t really think the fuel filter was the culprit in my case, I***8217;m glad I got it due to what I found below.

When I went to disconnect the F connector on the MAF boot, I noticed that the smaller bottom line was decayed, brittle, and cracked. It broke half into as I was pulling the F connector out of the boot. The other end of this line connects to the fuel filter regulator valve. It was almost in as bad of condition. The line is made of plastic with a short piece of rubber hose on both ends. So what I did was just remove the rotten rubber hose on both ends, lubed the plastic ends with a dab of petroleum jelly, and pushed a another short piece of 5/32***8221; vacuum line up on it. Had I known this line was bad, I would have just picked up a new one when I got the other parts, but since I didn't I had to improvise, as the dealer is 175 miles away. If I had not of replaced the fuel filter, I doubt seriously if I would have thought to check that end. I think this was contributing at the very least.

BTW, after I had done all the repairs, I pulled the codes again and had both P0174 & P0171. I***8217;ve driven it about 60 miles since the repairs and no codes pending or stored. Got a road trip tomorrow and have my fingers crossed that this issue is resolved. Thanks for the info guys.
 
#24 ·
im not sure if this is relevent or not but when I had those first two codes P0171/P0174. the mechanic that fixed my car said that there was a vaccuum leak and it was, i think, connected to the dipstick hole (an L shape hose connecting to it was worn). he said something about the dipstick hole having some kind of suction. dont know if thats true but what he said fixed my problem. hope i helped
 
#25 ·
Sorry for not posting in a bit. Since pounding away on this my grandmother passed and I had to drive to NY. Thankfully the pipe is still good and I was able to get the fuel filter on before needing to leave. It was a good test. Actually got 28.3 MPG (per avg on console) while going through VA. I hadn't had a chance to check for codes until today and there are three P0171 and one P0174 in the DME. No SES and they were at different mileages. I have to convert from km to miles to see where exactly they might've happened as right now it seems to be a very weak leak and only surfaces under heavy load (i think). Once I get back home I will probably try the tape around the DISA gasket to see if it changes anything but kinda doubting it'll help. I'll also check the gasket on the dipstick as i really never checked that (thanks for suggesting that HoTbEEmEr).

@DaHammer: how'd the road trip go? any codes?

oh and btw, is it normal to have sand come out of an old fuel filter? lol
 
#26 ·
Forgot to mention that while checking the codes today I had the car idling and checked the exhaust in INPA and the post-cat sensors dropped all of sudden and then picked up again. This was the oxygen reading and not the heater reading. I'm starting to wonder about them, too.
 
#27 ·
Road trip went fine. I put around 500 miles on her since the repairs and no SES light yet. When I was almost home yesterday afternoon I stopped to fuel up and put a container of Chevron fuel injector cleaner in along with 7 gallons of premium gas. Probably put about 50 miles on it since then. I haven't driven it today, but I did go out and pull the codes just now. There is 1 code pending, P0041, which is 02 Signals Swapped. Not sure what that is all about, since the 02 sensors have not been touched on this car, and there is no way the wires have been swapped. Prehaps the DME got confused or my scanner is one. Anyone have any ideas?
 
#29 ·
I recently had codes p0170 p0173 p1188 p1189 and it was a vacuum leak in the valve cover that caused them. They actually went away on their own and have yet to return 200 miles later.
 
#31 ·
The idle was pretty steady. I did some searching around here and someone else mentioned the codes and how they went away after they changed the MAF and fixed a small leak in the VCG. I figured it's much cheaper to check out the VC than to replace the MAF and the next day my CEL shut off.
 
#32 ·
I think I have finally fixed my leak. I've been reading more while buried in other things and found this thread showing the differences between the seals of an old DISA and a brand new one. Somewhere in there someone mentioned that once you remove an older DISA it can create a leak even if it wasn't prior. Mine (below) seems to be just a little too shrunken to seal properly so did the double-wrap of electrical tape to it. I wanted to take pics of it wrapped but totally forgot and was sort of in a rush to get the intake back together.

How I did this was to take the tape while on the roll and wrap it around the gasket area twice, making sure the edge of the tape was against the bigger part of the DISA housing. I made sure to cut it with a razor blade right before the overlap so not to create a small highpoint. Then I took the razor and trimmed the excess just above the gasket area, basically cutting it in half (though this wasted that part of the tape). When I mounted it in the manifold it was definitely tighter fitting and needed the screws to fully sit in the manifold.

So it seems that if you have an older DISA and you remove it from the intake manifold you probably need to tape the gasket or use RTV sealant to seal it up again.



Now, I need to fix my LR window regulator and someday find a window switch 'cap' (the black plastic thing you actually touch to move the window). And replace the rear bumper/fender clip. then something else probably.
 
#34 ·
Yeah no light. Actually, never really had a light since changing that one CCV pipe but was getting the same codes stored in the DME (P0171,P0174). But I did clear the codes when I changed the pipe and have cleared them since putting the tape on the DISA. Not too many miles but no codes so far.
 
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