Failed Emissions

[CB-M3]

I failed the HC (PPM) and NOx (PPM). Shop said it is probably the CAT cause my NOx levels were almost double the standard.

Standard Current Reading
HC 146 161
NOx 1134 2143




What you guys think? I have no CEL either. Even if I get a new cat I still have to bring it back to the shop to get the readings again.

Car is a 1991 318is with m42. Bone Stock.

[decay]

this is an M3/S14 car?

stock chip?

[jlevie]

While the catalytic converters could require replacement, intake leaks could also cause this. The failure are occurring at lower engine speed where the affect of an intake leak will be greater. The leaks could be causing lean misfires which will elevate HC and NOX. A smoke test and a booster check will tell.

[CB-M3]

i took it to the shop I been going to for repairs and showed them the report. They suspect it is the cat also cause the NOx levels are so high. What is the easiest way to do a smoke test without a machine?

[oldmann]

Do the stomp test. See what codes come up. Sensors will do what your getting. The O2 sensor for sure.
Vacumm leaks , the same. CK the intake boot, common failure.
New cat without fixing everything else is wasted $$$.
CK your fuel pressure, FPR, fuel filter.

GOOD LUCK, just went thru this in Denver. Passed, FINALLY

[CB-M3]

I will check the engine bay for vac leaks and the common stuff. New cat was $89. Just needs to be welded on. I'm just on limited time to get car inspected. Don't know how fuel filter or FPR would affect those emission levels. I've dealt with fuel filter/pressure issues before and if that was the case car would either have trouble starting or stall. Thanks for the info about the stomp test. Didn't know about getting faults without a scanner.

[vert_this]

your old cat is worth more than that pos aftermarket for salvage, assuming the media is still in it which no check engine light I'd say its there. So if I were you I would make sure they don't get your old cat.

[CB-M3]

good advice. I knew platinum goes for $ at the scrap yards but I will make sure they give me the old cat back.

[CB-M3]

so I did the stomp test and got Code 1222. According to the list it is below. Could be anything. I did notice I have to clean the IACV cause it is little rough on idle. Could that trigger this code? Next step is check intake boot, vac hoses and clean IACV.

1222 - Lambda control fault code is produced when Motronic system in Bosch control unit receives signal indicating that air/fuel mixture is either excessively rich or excessively lean for period of time loner then 10 seconds. Majority of the causes that affect drivability of the car can be responsible for DME flashing this error:
air leak
defective Air Flow Meter ( AFM)
bad engine temperature sensor
incorrect fuel pressure
problem with injector(s)
defective evaporation system
empty gas tank
issue with spark plugs
problem with valves
etc.

[CB-M3]

Well, just took out the IACV to clean and noticed several hoses cracked. Hunting for p/ns now so I can replace them while I'm in there. Pretty much I need these.

[CB-M3]

Worst crack I found. Not all the joints have clamps so this was probably one of the bigger contributors. Some of the ends with small cracks I put on some hose clamps to keep it solid. I will have to end up buying a new one for the hose below. Either that bypass that center connection and go straight to the intake boot from the IACV.

[vert_this]

Also found out that there are 2 holes in the intake boot. Only one of them had hose coming of it. What is the hole for the one closest the manifold for?

you can patch those holes in that with wrapping it with duct tape. I know not ideal but may get you to pass and you can later get a new boot which is like $30..just an idea.

I'm glad they did away with that BS in my state.

[oldmann]

Worst crack I found. Not all the joints have clamps so this was probably one of the bigger contributors. Some of the ends with small cracks I put on some hose clamps to keep it solid. I will have to end up buying a new one for the hose below.

2 holes in boot, only one used. Other should have a plug in it.

1222 can be O2 sensor.

Shoe Goo works wonders on the intake boot cracks. Take that boot off and scrub it in the sink inside and out with dishsoap, before the Shoe Goo.
Shoe Goo will hold up in the underhood heat, and is flexible.

[CB-M3]

The intake boot is fine. No cracks seen. The other did have the plastic plug in it. I just didn't realize it cause it was blended in with the intake book. Yeah I read 1222 can be O2 sensor but there is a separate code for that. I'm taking all the steps to catch the vac leaks first then moving on from there. The cat will be the last thing I do because if I don't diagnose the lean/rich condition I will destroy the new cat later on.

[oldmann]

The vac. leaks are most likely the source of the failure.

You can use heater hose for that line. Run it direct between the ICV and intake boot. Different sizes for each end. Take the ICV and the fitting from the boot with you to the parts store, use a hose that almost won't go on the ICV and a loose fit on the fitting, clamp accordingly.