E46 320i 2001 rough idle , weard codes ( sometimes )

[Stefan666]

Good morning, been reading here for a fair bit of time
but now i do need some thinking help.

The bmw starts normal , but runs rough idle , if you make it last a bit it will get a misfire on *fill in any* cilinder.
( roundom.. can be nr 1 .. can be 3... never the same )

I get code 174 , and 173 ( top of my head, both fuel banks lean )
But, that sometimes popped up since i got this car, never given any problems.

month ago, the idle trouble started, diagnosed a bad MAF and after replacement the problem was gone.
( gone as, for a few days )
Also replaced the intake rubbers ( both ) as they seemed not that perfect anymore.
Checked the black-box-with-the-motor-flappy-thing inside , works fine .

When the engine warms up nice ( a bit of drive ) the idle problem is mostly gone, restart.. and back goes the rough idle

Now, somewhere in that last period i also got the 599 code..

( could it be linked, and does the thermostat also manages fuel ?? )

So far extra checked :
- Fuel pressure , good, and holds good ( no indication on a bad injector or fuel pump )
- Air leaks.. can't find any, no response on break-cleaner on any parts

Questions.. could it be a bad o2 sensor ? ( how can i test these ? )

But more..
With code 0174 and 0173 + 0599 ( recently ) .. im ending up getting in the cycle of "replacing on the gamble"
( as engine temp is just fine, i wonder if its related to my bad idle problem )

Some directions are very welcome !



As i think my writing is a bit confusing ( non native, sorry )
Compressed:
- Since i got the car, sometimes had code 0173 and 0174.. never effected driving, could be "gone for months" and after a reset
not come back for long periods..
- Rough idle problem started, replaced MAF , had effect for a very short time.. rough idle problem is back
- Around the same time , 0599 code also came up.. ( is thermostat also linked to the fuel mix ?? )

now lost.. need help

[MarcoZandrini]

Codes P0171 and P0174 are classic indications of vacuum leaks. P0173 is a fuel trim issue with bank 2. P0174 is a lean condition on bank 2. The P0599 code means that the thermostat heater circuit isn’t working. This code has nothing to do with the other codes. Basically, the thermostat has a heater circuit that is used to help the thermostat open quicker when the engine computer (DME) sees a major load on the engine and needs to open the Athermostat quickly. This increases coolant flow through the cooling system.

Id have the intake smoke tested to find the vacuum leakS. Proceed from there. Then see if the heater circuit in the thermostat is open or shorted. It’s a heating coil so it should have only an ohm or so of resistance.

[dworthy]

+1

And I would only use BMW OE or Behr who is OEM for BMW on that part - Thermostat.

P.S. the thermostat and housing is 1 part.

[Stefan666]

Thanks gents, guess i'm back on trying to find a vacuum leak
* guessing* for now its that , apparently, often busted vent-thingy ( for what you got to remove the air-intake to replace it ) - says google -

Thermostat SEEMS to work fine, but will replace it anyway, not that big of a operation
Better safe then sorry.
( i hate error code's anyway )

My guess was, ( but wrong ) , that the busted/nearly busted thermostat could relate to the bad idle at a cold engine.
( cold engine, could be a different fuel map or something.. ) was thinking to far.

Just got to build me some kind of smoke-device , will work on that.


Weard thing is mostly, its not a constant problem.. yes, its -often- but once , while driving clearing the code usually keeps the code away for a while and
not many difficulty's driving.
- until the next start.. story starts all over again -

[Stefan666]

Follow up, as in.. why not
It took a while , mostly due
1) arrival of parts
2) work
3) bad weather ( have to work outside )

But, replaced the CCV complete, what turned out to have the problem, that the exit ( to the dip stick )
was broken clean-off.
Well, that should reduce some oil consumption to start with

The replacement itself turned out to be a beast, started with the "ninja" way and try to get
the new CCV unit in place without removing the air-intake-block.
After a hour, and a good dose of rage i gave in and pulled the intake block off.
( as i was working with limited daylight including rain.. storm ... you might suspect i did not enjoy that part )

But.. in total 6 hours later from start scratch, was putting back the final parts..
Fuel leak, could not get the fuel rails to close on the injectors, tried several ways.. they would just not seal ( i say, fuelshower.. )

Called in a frind for some fresh eyes on the case, he tried a different way ( first fit injectors to the rail, then place the entire rail with injectors on the engine )
And, this proved to be the trick..
* those cursed clips... who invented that system... * ... i might wanne have a speak with him in a dark alley where nobody can hear the bastard scream.

Back from first test drive, code's so far stay aways ( 171 + 174 ) , victory ! See how it handle's on the longer drives.



Total repair time, including a bodged fuel rail montage and having to jack the car due losing a injector clip and finding it back in the dark.. 10 hours.


Oh, and very vital..
Runs smooth again at stationair
( not fully sadisfied yet, think its a bit slow on the pickup when accelerating.. cpu might need to wake up a bit ... )
Will try to reset it , see what that does next drive

[MarcoZandrini]

Yeah, the injector clips are a PITA.

For or future reference, the hard part of the CCV swap is the hose that runs from the air distribution manifold to the CCV body. The connection at the CCV body requires a 90 degree twist. I found that putting the hose in place and rotating the CCV body 90 degrees do that its bottom is facing the engine is the way to go.

[Stefan666]

I really tried.. oh did i try !
But with my hands and the box , well.. something was to much

Think i did make a mistake , code 0341 now , might explain the shitty engine pickup. I think i can see a plug hang lose under the airbox , so i assume i just screwed up and forgot to plug it back in. ( camshaft sensor??? ) to bad, hands to big to do it "on the road" will have a look when im home with the tools.

[Stefan666]

More update... now home and ... with tools

Well , turned out that in the rush/darkness and being totally fed up i fucked up a bit more..

Protip, if you unplug stuff to move that connector box located left off the airbox..
Check.. 3x.. if you got all the plugs back in ... helps.. car runs way better with a sensor attatched to the computer.

Mostly amazed, that the car even ran , turned out that under that "electric box" there is another plug you have to put in,
well.. i accidental somewhat missed that plug to in the rush.

Code's gone , 170hp again on the rear wheels, and the beamer runs like it surpose to
- declares victory for the day -

Will sort out that 599 code later on the next service or something.



Oh , another tip... when you have that -eureka- moment somewhere next to the road, and see -that- plug..
Don't try to jam your hand in between the block and the airbox , against better knowing it won't fit..
A little lower.. there some mighty hot parts.. trust me on that... found em...