failed emissions help please

[der affe]

i went through emissions today and failed....crap!

the car is an 91 325i
2.7 stroker, P&P head, dbilas itb's, 300ish duration cam of unknown manufacture, shorty headers, BRAND NEW CAT INSTALLED LAST NIGHT!, new plugs last month, seafoam'ed the topend and tank the weekend before the plugs, did a new O2 8 months ago (four of which the car wasn't driving), and it has a split second piggyback for the MAF conv.
every time i have taken it through emissions, i just put a new cat on it (big cam destroys it over time) and through it goes with flying colours.

this is the first time it was a no go.

here's what happened today:
get the car up to temp and the cat nice and hot driving to emissions testing station.
pull in there is no line to wait in. hand over the keys, stand in the booth.
watch the guy test the car 5 fucking times in a row!!!!!!!!
so i ask him what the hell is going on? "it shows you don't have enough exhaust coming out the tailpipe like you have an exhaust leak or the new cat isn't letting enough through"
WTF? i know there is no exhaust leaks.
i pull it into another bay to test it on another machine at there request. test # 6!!!! now i am thinking HEAT SOAK!!!! go through the test and.....
FAIL: HC 1.00 allowable i blew a 1.09
PASS: the CO2 @ about half the limit
FAIL: the NOX 2.50 allowable i blew a 4.0

[BBY1104]

my 91 318is didnt pass either last year...still dont know why?

took it to a mechanic, paid 150 for a full diagnostic and he could not find anything.

oh well maybe it is your o2 sensor or AFM?

[Farbin Kaiber]

my 91 318is didnt pass either last year...still dont know why?

took it to a mechanic, paid 150 for a full diagnostic and he could not find anything.

oh well maybe it is your o2 sensor or AFM?

exact same issues here between the two cars of course.

[BBY1104]

yea mine did the same thing

i had high o2 as well

my cat sounds bad and o2 might need to be replaced

[Farbin Kaiber]

yea mine did the same thing

i had high o2 as well

my cat sounds bad and o2 might need to be replaced

I bet you couldn't "decode" half of the OP. Does a bad cat meow more?

[der affe]

going to clean the MAF wires tomarrow and the O2 is pretty dam new and according to my other wise useless arm-2 (AF gauge narrow band) it is functioning and dithering away and going to open loop at the right time and closed loop when it is supposed to.

also going to test the wires

clean the cap of any carbon tracking and clean the terminals (prob wont make any difference)

the crank position sensor is a couple of months old (shouldn't make a difference)

the air filter is clean.

changed the oil (with mobil 1 15-50 and a new mobil 1 filter) last month

the coolant and t stat are 2 months old

the car is running great, i am getting around 25-27 mpg in town babying the crap out of it. i am kind of at a loss

[der affe]

does anyone know off the top of there heads what the allowable resistance values are on the plug wires. i don't think they are stock, they are blue with oem ends etc. BERU maybe? i think they might be from BMP?

[abepark]

the *new* cat and him saying exaust leak kind sound interconnected....thats just some insight

[ethree]

Did you change your plugs? If so how did they look?

[der affe]

don't use Mad Hatter muffler in central phx!!
they overcharged me, said that they had the BMW flanges in stock for it, when i showed up they didn't. i ok'ed them to cut off my old ones and reuse them for the new cat, then charged me the same as if they had sold me new flanges.
NEXT....they used 2" tubing and didn't make a step down for the slip joint for the ends of the shorty collector (1 7/8" ). insted they used u clamps and cranked them down.

HUGE EXHAUST LEAK!!!!!!

it was so bad they they were having probs at thge testing station with not getting enough flow to test!!

i seafoamed the top end and it left puddles at the front of the cat section!!!!

they also mounted the cat at the very rear of the cat section, about a foot too far back!! i did a temp check with an infered thermometer and it was only getting up to 700 deg!! (it is supposed to get up to 1100-1200 deg)

SOOOOOOO

i call them this morning. told them what i thought of their work and what they did wrong. in a nice dissatisfied customer way. i told them what they did wrong, and suggested what they could do to remedy it. i got this responce.....
"hey that was a hard job" (BS!) "we had to drop the cat down"
so you are a muffler shop that is your job!
"the tubing you have is an odd size, we didn't have the right tubing to fit" you said you did, and if you have a problem you should call me the customer!
so you let a car leave you shop with your name on the r/o with a reapir like that?

i am now stuck taking it back to them to and paying another $30 to have the put flanges on the slip joints, and they are going to repair their shitty work for free. i am still getting fucked so i am going to call the owner of the business and bitch to them. we (the mercedes benz dealer's body shop) are no longer going to send them our work either.

fucking inbelievable!

[der affe]

Did you change your plugs? If so how did they look?

took them out and checked them, they were a nice chocolate brown

[Farbin Kaiber]

I have only found one Exhaust shop in Southern California that did work to my level of acceptance.




Most muffler shops are just one step abve most fly-by-night white van speaker retail salesmen.

[Turf1600]

Too much NOX means you're running lean.

[der affe]

they have been around for YEARS! and i have used them a bunch of different times through shops i had worked at.

i would usually use Apache muffler or Scottsdale muffler and have been very happy with their work! this place is just close and convienent to work. they also charged me $150.00 to put it in and i provided the cat!
i usually pay $100.00 from Apache or Scottsdale. so now i am going to be an extra $80.00 over what i would have paid.

next time i will just buy dounuts and straight pipe and make my own like i should have done!

[Farbin Kaiber]

You'll be looking for that EGR valve for a looong time. These cars were not so equipped. If it had one and it was hanging open at idle, it would idle horribly anyway. There primarily for the reduction of NOx, not HC or CO.



Anyway, on to your problem. Look at your Vane Airflow Meter, located on the airbox. It's the sensor the intake tube attaches to. In one corner of it there will be a little plastic plug. Under it you will find a screw. Take note of the orientation of the screw (you'll want to put it back to where it was) and turn it out, making sure to count the turns (again, to facilitate putting it back where it belongs.) What you just did was open up an internal air bypass a little further, letting more air in past the sensor. Since it goes around the VAM, it doesnt add any more fuel for that quanity of air. Your car is now running leaner at idle. (This adjustment only makes a difference at low airflow so it messes with idle only)



HC is hydrocarbon, unburnt fuel from somewhere. Misfire? Too rich? CO is carbon monoxide. Not enough oxygen for the fuel burnt to achieve "optimum" combustion. Again, too rich would cause it. Leaning out will help both of those tests.