code P0170 96' 328 - fuel trim bank 1 ?

[7808]

i pulled the cel code from my 96' 328 i got P0170 fuel trim (bank 1) anyone know what that is ?

its kind of a vague discription, i was hoping for a o2 sensor or somthing easy code this sounds like it could be a few things, anyone know what i should look for?

thanks

[7808]

well i didnt feel like writing down everything so i snapped pics when i went and scanned it. im gona start lookin everything over but meanwhile maybe these can tell more to some one whos familiar with reading these






freeze data?











the air metering thing makes it sound like a maf or vac leak issue. car was not running so not sure why it shows a rpm or load unless its saying thats when the code happened


my MAF looks very clean inside..

[thejlevie]

Those codes could be any, or a combination of, aged pre-cat O2 sensors, intake leak, failed CCV, contaminated MAF, or a fuel delivery issue. If the precat O2 sensors have more than 80K on them, replacement would be indicated. Then check for intake leaks. A visual check and/or spraying carb cleaner around while idling will generally find any leaks. But the definitive test for an intake leak is to have a "smoke test" run. A crank case pressure check (should be 3-4" of water) is the diagnostic for a CCV.

[7808]

whats ccv? i pressureized my intake manifold via the brake booster hose and it did not hold air.. trying to find where

[sbullard878]

Crank case vent, it plugs into center of the intake via a gray rubber grommet has a hose connected from it to the dipstick tube and has a black plastic hose that connects from the ccv to the V/c. I would check the rubber hose connected to the dipstick tube. If it has over 70k miles on the engine I would replace all three items I talked about above also check the intake boot and hose coming off the bottom of it going to icv(Idle control valve) and the rubber grommet that the Icv slides into in the bottom of the intake these are your problem areas on obd2 e36 cars. Oh and by the way blowing into the intake will do nothing more than waste your time because you have some Intake valves that are open no matter where the intake cam is located. hope this helps and let me know what you find

[7808]

very good info thanks.

[7808]

well i had my airbox off, and was blowing smoke into my brake booster line, but the only place smoke seem to come out of was the tube that was loosly sitting in the bottom side of my intake box before i took it off, if thats hose sees vacuum, thats kind of odd because going to your airbox is kind of like one big vac leak..

[elements018]

try checking everything over for vacuum leaks or fuel leaks or anything. This code isnt for O2 sensors

[7808]

the hose i found kinda loose was on the bottom of the intake elbow after the maf. i replaced the clamps and the gromet on my brake booster line because i could turn the lines easy by hand we'l see if the code comes back. i put a clamp on that fat hose on the bottom of the elbow too.

[7808]

spayed my maf out with carb cleaner, re-did the clamps on my brake booster hose, and the gromet, and the tube under the intake elbow. starting with the easy stuff. cleared my cel with a scanner, it came back after about 15miles of driving. this time is showed 6 codes but they all looked like the same numbers as above..

still not sure what it is. i might just give up because im 99% im going to be running megasquirt soon so im only concerned with leaks or other malfuntions that wont be gone when i ditch the maf and extra o2 sensors

[techvet]

The discussion has gone on for quite a time, but I have not seen any mention of how the engine runs, or what the exact problem is aside from the fault codes. But the heck with how it runs... here are my thoughts.
It is definitely not an 02 sensor problem. The pre-cat 02 sensor of Bank 1 (based on P0170 being the root cause of the check engine light) is simply reporting to the DME that there is a lean or rich condition which the DME then tries to correct (by adjusting adaptations/fuel trim). The fault P0170 is then set by the DME once it exceeded
set values/ratios for adaptations (+-.03 for additive adaptation and +-20 for multiplicative, aka short term & long term).
A defective crankcase vent valve or the hoses connected to it, if any of them are cracked or leaking can give you a lean situation similar to your problem, or misfire faults due to the oil being sucked (note that one hose goes to the dipstick and the other goes to the front top of the valve cover).
You can check this by spraying brake cleaner beneath the intake manifold where the vent valve is and also along the hoses from end to end.
It is unlikely that leaks from the intake hoses from the MAF going to the throttle valve, including those of the idle air valve would not cause both banks to set faults.
But why is the fuel trim fault only for Bank 1? Then check the intake manifold for possible leaks specially along the sides of cylinders 1 to 3 (bank 1). If there is none, and you can not find any other vacuum or air leaks (specially with the crankcase vent valve aka oil separator aka cyclone separator), then it is a bad MAF (no matter how clean it looks).

[7808]

car runs fine, i wouldnt think anything was wrong if it wasent for the cel.

i was pointing a unlit propane torch all around my intake manifold while the car was running and didnt notice anything change in the idle.. i will look for this crank case vent valve, im guessing thats what i call a pcv valve

also if you notice the pictures, its throwing a code for bank 2 also

[SergeK]

It can be many things really.. You need to hook up to a better, BMW Specific code reader..

Fuel Trim can be anything from a bad o2 sensor to a bad injector.

The Air metering one can be a vacuum leak or a bad maf. Im leaning towards maf.

Long/short term fuel trim is basically the adaptations the car has set. Clear the codes and unplug your battery for 30 mins. Resets the ecu basically. Then if/when the CEL comes back check again right away.

This can all be from a bad O2 sensor or a bad MAF.

[7808]

ive cleared it twice so far with a code reader. both times it came back in about 10-20 miles of driving.

why doesnt the bently manual have any kind of trouble shooting or testing for the maf? seems wierd

id take it to bmw for them to scan it but im sure they'd want some rediculous amount

[techvet]

The only testing that a normal person can do is to check for power and ground to the MAF (pin 1 is ground, 3 is 12 volts from engine relay), and continuity of pins 2 & 4 of MAF to pins 8 & 7 of DME.
There is no way that you can correlate the amount of air going through the MAF with the amount of signal that it gives to the DME (except to approximate say at fixed rpms,
fixed signals, but you can not determine the continuously variable air mass and signals
being generated without sophisticated equipment). Thus you can not really diagnose the MAF minutely.
If your engine runs rough (which it is not as you say), then if disconnecting the MAF results in better engine running while in default setting, then the MAF is bad.
Most dealer techs simply swap MAF's in cases like this because they have access to parts.
But, back to the topic of 02 sensors. Rarely if ever, in a BMW would a fuel trim or adaptation fault be due to a bad 02 sensor. Bad BMW 02 sensors set their own faults.
Provided that an pre-cat 02 sensor cycles normally look elsewhere for defects.

[7808]

well today i tried more propane around the oil seprator and intake manifold with no change in idle, then i ohm'd out my injectors for the hell of it. pinched some lines, propane around the air pump lines, still trying to locate my fuel pressure regulator lol. bently manual photographer = shit

[sbullard878]

fpr its under the car in front of the fuel filter drivers side. but it needs a ccv and lines I replace almost one a week trust me

[7808]

im gona dump that thing then, replace it with a catch can

[techvet]

The fuel pressure regulator is at the rear bottom end of the fuel rail. It is true that if you have insufficient pressure, your engine would set a fault for a lean condition for both banks, even lean misfires for bank 1 or 2.
But you said previously that the engine runs fine. But it is easy to check fuel pressure so go ahead and do it.
Assuming that you see a low or intermittently low fuel pressure, it can also be due to a bad fuel pump on the right side of the tank or bad siphon device on the left side.

[sbullard878]

techvet this is an obd2 car the fpr is on or in front of the fuel filter and Not on the fuel rail like the odb1 cars and 7808 replacing the ccv with a catch can is not going to solve you check engine light it will probally through more codes......

[7808]

why would it throw more codes? its a mechanical system - no wires, if its leaking un-metered air and i seal up the port on the manifold, and T off another easier to see vac source like the brake booster line for a catch can from the valve cover, it will still do its job

that thing is just a fancy draining catch can if i understand it correctly

also my intake manifold will be seeing postive pressure soon hopefully so its going to have to be delt with anyways

[7808]

havent found much so i decided to rip it apart. this thing had to go anyways because of future plans.

the unit itself. most the lines attached to it self destructed when removed


looks like poop, just like the inside of my manifold and intake ports, which now have dirt in them

[7808]

well i possibly figured out my CEL codes for fuel trim this and that, i re-did all kinds of hoses and vac lines and new intake manifold gaskets and replaced the seprator setup with a catch can, fired it up, ran fine but idle wasent as smooth as i thought it should be, so i pinch the hose from my catch can to my valve cover and the idle instantly changed, little higher and smoother, thought that was wierd, so i pluged the line to the catch can, and im venting the valve cover to the air, car seems to idle smoother.. cel has not came back yet but some times it takes a day or so of driving so we'll see
so, im thinking i have a vac leak on the valve cover, i guess i will know if the cel stays off for a few days ill hook it back up and see if it apears

[jeff328i]

I tried plugging the large hose from the valve cover to the cyclone valve, but then the engine started sucking oil via the cyclone dip stick drain. So I plugged everything associated with the cyclone valve, but fuel trim error would never stay gone! I just wanna get the damn thing CA smogged!!!
Seems BMW engineers have created a temperamental thoroughbred, why they have to sell new breeds with free maintenance.