m20 engine failing horribly on NO(x) emissions!

[JrCamacho]

So this has been an ongoing thing with my car: Its failing Horribly on NO(x).

im getting readings of over 1800+ labeling my car as a gross polluter. This is what i have had changed since ive owned the vehicle:

All coolant hoses
Radiator
Thermostat housing
Water pump
Timing belt + Tensioner
Thermostat
All Vacuum lines
Spark Plugs
Replaced Catalytic converter
Brake booster (had a huge vacuum leak)
cleaned ICV
Valve Adjustment
Replaced fuel tank
Replaced Fuel Filter
Replaced fuel lines


Things that im thinking that are causing my NO(X)

Engine running way lean (dont know why though)
Advanced timing.. just a little bit?
the engine sounds like it has a tiny 1 cyclinder misfire...

any help is GREATLY appreciated, my other numbers for the CA smog are great all WELL under all readings EXCEPT NO(X)

help mee!!!!

[JrCamacho]

oh yeah, the 325i idles solidly at 750rpms.

[russhixmo]

O2 sensor, colant temp sensor, and check for exhaust leaks, go basic first b4 you just throw parts at it

[jlevie]

The first thing I'd do would be to have a smoke test run to see if there are any intake leaks. If none turned up or if only very small leaks turned up the next thing I'd want to see is what the A/F ratio is on a dyno. If it is lean I'd do fuel system tests and have the injectors cleaned and flow tested. And depending on where it is lean and by how much I might replace the AFM, ECT, or DME.

[urbancynic]

What spark plugs are you running?

Check the basics before you throw money at it.

How long ago did you change the cat?

[JrCamacho]

02 sensor has been replaced.

I have a feeling it may be injectors, could an AFM cause my car to run "lean" like that?

Im checking my timing when i get home, too make sure its not advanced or what not.

ive fixed all intake leaks besides any exhaust pieces before the 02 sensor, i guess i could do those first, time is running out, and i just have no time since im working so much (who isnt).

the PO had some bosch plat. +4 that i put in.. i think i should go to original ones.


I do notice that the car is somewhat sluggish, and it never shifts right, always like its a CVT or something, when i floor it, it feels like its sluggish.. not as snappy as it should be, it never downshifts to the right gear, and it doesnt seem to get any power until 4k and beyond, and even still... i feel like the car should have some "scoot"

[jlevie]

The ignition timing is controlled by the DME and isn't going to be off except as a result of there being other problems with the engine management system. If you haven't had a smoke test run, you really can't say that you have fixed all intake leaks.

[urbancynic]

Get rid of those platinum plugs. M20's don't like them and they can make the car have higher NOx.

If you're way off of the target though they may only be part of the problem.

[MattAvino]

heres your problem- california.

[JrCamacho]

i know california is my problem.. but i came looking for helpful hints/comments to help me get my car smogged as it is my only DD right now.

Things that im checking today:

-Replacing plugs with OEM equivalent
-smoke test
-crank sensor
-knock sensor (there is one right?)

i needa get this thing smog ready today! help me out!

[urbancynic]

How about the coolant temp sensor for the ecu?

[E30_fiend]

^^^^
What he said.

And no, there are no knock sensors on the m20. Also, unless you have an adjustable cam gear, the timing is set and cannot be adjusted. There is a possibility that it may have jumped a tooth but then it would run like shit.


Taylor

[Izzy]

^^^^
What he said.

And no, there are no knock sensors on the m20. Also, unless you have an adjustable cam gear, the timing is set and cannot be adjusted. There is a possibility that it may have jumped a tooth but then it would run like shit.


Taylor

Im pretty sure he is talking about ignition timing. Too far advanced timing will cause higher cylinder pressures thus creating more Nox

[JrCamacho]

my timing is on, I am a lexus technician and i did all the work myself, set on TDC everything..

I have an UPDATE since i brought my car to a GOLD SHIELD station, since thats all i can take it to now for my smog...:


okay as you guys have known, since I bought the THIRTY back in april of this year, i have been Desperately trying to get it to pass smog. Throwing parts left and right, fixing vacuum leaks, replacing sensors, etc. the damn thing STILL FAILS on NO(x).

Since failing 2x at a shop, and getting labeled as a "GROSS POLLUTER" i had to take it to a certified gold shield station. I got a call yesterday from the guy there and this is what he told me:

"your plugs are wrong, and the o2 sensor is bad"

I can understand the plugs being "not the right ones" (using Bosch Platinum +4 instead of OEM), and that SHOULDN'T raise my NO(X) levels up to 2800+ PPM!! And what about the oxygen sensor? i just replaced that maybe 4 months ago... theres no way that it should be bad.. or perhaps.. its the wrong one?

-Bosch 13231 Oxygen Sensor, OE Type Fitment ---- that's the one i bought from amazon, was told it should fit, it did fit, plugs right in, and i actually didnt notice any performance issues while using this o2 sensor.

-Bosch (4417) FGR7DQP Platinum +4 Spark Plug ---- that's the plugs that im using in the m20. What plugs should i be using?


In case you don't know, my car is only failing smog by one thing.. NO(X).. and im talking screaming it over 2800 PPM, which is absurd.



My question guys,... What oxygen sensor and plugs should i use? im pissed as im a technician and i paid $100 for a diag and thats what the fuck he told me is wrong.. After i've already fixed/replaced the major problems with my car.. the PLUGS AND SENSOR as causing me to fail? AFTER i already replaced those things with NEW items? I am seriously lost here fellas. Smoke test showed no vacuum leaks.

perhaps maybe an exhaust leak prior to the oxygen sensor? didnt see one.. but it might be a small one? would it throw it off that bad?

[JrCamacho]

How about the coolant temp sensor for the ecu?

The coolant temp sensor, are you referring to the one on the T-stat housing?

I have replaced the one on the radiator, as well as the two sensors on the t-stat housing.