I can't pass emissions

Hello everyone! I got a huge problem that I cant solve. I got a 2002 745li that can't pass emissions. Check engine light is on for "emissions related fault" code p2177 and p2179. Meaning its running lean on idle for both banks. I've done all parts required but it's still popping up. Once every blue moon it would turn off but would come back on within 25 miles. I get 14mpg combined driving normal. On the highway at 65mph I get 24mph and 55mph 25mpg. I'm really at my wits end and so are the specialist. I know these e66 have a carbon build up issue in the engine, that can be removed with a machine ($$$$) but im not going to to do that. Please help

Originally Posted by 02x745Li

Hello everyone! I got a huge problem that I cant solve. I got a 2002 745li that can't pass emissions. Check engine light is on for "emissions related fault" code p2177 and p2179. Meaning its running lean on idle for both banks. I've done all parts required but it's still popping up. Once every blue moon it would turn off but would come back on within 25 miles. I get 14mpg combined driving normal. On the highway at 65mph I get 24mph and 55mph 25mpg. I'm really at my wits end and so are the specialist. I know these e66 have a carbon build up issue in the engine, that can be removed with a machine ($$$$) but im not going to to do that. Please help

What exactly have you changed?

Everything

Provide more info. How many miles, what have you change exactly, etc.

Run some fuel system cleaner through it...I like the 44k stuff. Usually about $30 a bottle. That should help unclog components in your fuel system.

Those codes mean air leak, maf sensor or o2 sensors but most likely air leak somewhere

So I did a search for you but came across nothing but useless open ended threads. It appears that everyone that had this issue never came back to post a solution after they came here looking for help! I supect the same thing, it must be a vacuum leak or possibly a dirty or bad MAF which I am sure you looked at already.

can you see the freeze frame data with the code(s)?? obd2 protocol requires it to be accessible on certain code reading tools (if it has the ability to clear them, ff data s/b atainable) this will tell you what the parameters are, whether the dme (pcm) is trying to add fuel or take it away.

if you are getting such poor mileage, i do not see that as a lean condition. however, if the fuel trim is going negative, the pcm is trying to lean the car out as there is too much fuel getting into the combustion chamber.

if the fuel trim numbers are going positive, then it is reading more air than is actually getting into the combustion chambers.


fuel trim is in long term (ltft) and short term (stft), and if it is going negative, check your fuel pressure, fuel pressure regulator (pulse width modulated fuel pump on this one?), injectors (possible leaky injectors) and evap system. this is where the fuel would be coming from.

you should also check the injector pulse width as well. see if your code tool will be able to give you live data. (check the speed by watching rpm, and when steady, snap the throttle and see how fast the numbers respond...the faster the better....)

if real fast, you should be able to check the injector pulse in ms.


if the fuel trim is going positive, then check all of the usual suspects for vac leaks. a smoke machine works well for this, and if you have a neighborhood dj that has a 'fog machine', it would work. (you just have to work on the logistics of getting the smoke channeled intothe intake....) and low pressure (1psi) is all you need. watch for the smoke to show = find leak. fix accordingly.


*edir* hit a wrong buttonon my laptop & it all went wonky....sorry.

if no smoke machine then use a vacuum guage.

if vac looks good, in range and no indications of issues, then i would suspect a faulty maf. @ idle these things will be lower voltage output, and go higher on an analog design. not sure if bmw uses a hz system like fords or not, have not scoped a newer 7 series yet...


regardless, if running rich due to increased fuel trim, the pcm is controlling the amounts. this could be caused by a faulty sensor (usually not an o2 at this point...) or faulty pcm.

i hope this helps shed some light on the subject. this is pretty much basic diagnostic proceedure on obd2 vehicles (even pre odb2), which requires some special equipment and knowhow to use it. however, the know how will allow you to use more readily available equipment to get a better idea as to what is going on without resorting to throwing parts at it.




oh yeah, and what were the readings?? that would be a huge piece of the puzzle....

hc= misfire indicator
co= rich indicator
co2 = efficiency indicator
o2= cat efficiency indicator
nox= high combuston temps (usually *never* with high co)


df

i have been there before as well, hopefully you get it resolved.

Originally Posted by E92-Lighting

i have been there before as well, hopefully you get it resolved.

What was your solution?