Help me pass emissions..

[r4esh]

SO... my s52 swapped m3 is failing hydrocarbons at idle (see image)
The car : 1990 BMW M3 with OBD1 swapped s52.

• New sensors = cam, crank, knocks, o2 sensor, temp
• 3.5'' 540i MAF, CAI, Bimmerworld silicone boot, m50 manifold with m50manifold.com silicone hoses and kit (no vacuum leaks)
• TRM Tune for above stuff
• Other notes: new fuel filter, 95% sure no vaccum leaks... couldn't find anything, I AM running charcoal canister, the new o2 sensor is NOT boshe brand (someone suggested this was a concern) - Update: 21.5 lbs injectors and tuning is for it.

The Exhaust :

• Euro-Replica headers > Duel 1.75'' custom X-Pipe (where 02 is planted in center) > Duel 1.75'' pipe into Magnaflow High-Flow Cats (new x2, one for each pipe) > Duel 1.75'' pipe > Unknown Muffler.

Swap was "finished" about a year ago and we got it to pass last time by throwing a 325i chip in there... But I'd like to address the mysteries issue as to while its failing emissions.


Pretty much everything is new EXCEPT for the MAF - Anyone have any suggestions? Arizona's emissions aren't that harsh. I'm almost skeptical at this point that my tuning is the issue. I know everyone here favors TRM... buuuuut.....

[328ijunkie]

What injectors? And is the chip for the injectors?

[DesertBMW]

3.5'' 540i MAF, CAI,

HC means fuel unable to burn completely, I suspect there is no velocity stack on the 3.5" MAF and filter is mounted directly on it, there is a lot of turbulance there, MAF can't read the air properly.

Put stock M50 MAF, injectors, and stock 413 red label ecu with stock M50 chip in it. It should be able to be good enough to pass emissions.

Keep in mind that bigger engine emits more emissions. Emission stations expects a 2.5L engine so the limits will be tighter for 3.2L, you will also have to have a high quality catalytic converter.

[Jalves619]

Keep in mind that bigger engine emits more emissions. Emission stations expects a 2.5L engine so the limits will be tighter for 3.2L, you will also have to have a high quality catalytic converter.

This is a good point. Although in this case they are looking for a 2.3L 4cyl.
I wonder what the passing HC numbers are for the OBDII e36 M3

[r4esh]

Hmm, good input guys.
328iJunkie | 21.5 lbs injectors and tuning is for it... unless I was sent the wrong chip.

I'm dreading having to spend money sourcing an m50 maf, 17lbs injectors, and an m50 chip just to pass emissions once a year, but obviously willing to do it.

DesertBMW | Turbulance on the MAF? Yes the filter is directly on the MAF. You're suggesting that vibration at idle is causing the MAF to receive an incorrect reading and thus give me the score I had?

Really wishing I had gone OBDII right about meow....

[SwiftE30]

Are there any good junkyards in your area? You can usually find the MAF and injectors pretty easily there. ECU is another story. I have an extra one I can sell you for cheap. I have no use for it anymore.

[328ijunkie]

OBD2=win

OBD2 S50 on a Temp. M52 Flash

[r4esh]

Go ahead and rub it in 328iJunkie :P - At the time of the swap there was very little obdII information out there so I played it "safe"... kind of too late now.. Wouldn't really want to "go-back".. at that point I'd rather just go s54... <_< >_>

So that still leaves me in this predicament. No one has any ideas? My car wants me to throw money at it in other ways instead of just trying to pass emissions.

Anyone vote +1 on a bad tune? What else would cause such a high idle reading?

[hoveringuy]

Euro-Replica headers > Duel 1.75'' custom X-Pipe (where 02 is planted in center) > Duel 1.75'' pipe into Magnaflow High-Flow Cats (new x2, one for each pipe) > Duel 1.75'' pipe > Unknown Muffler.

When I fabricated my new exhaust I used Magnaflow high-flow cats. Went for an emissions test and FAILED.
Put the OEM M3 OBDII cats back on and passed with flying colors the following day.

The Magnaflow cats are good enough for OBDII cars where they just check for codes, but they don't clean well enough for OBD1 sniffer tests, IMO.

I also passed again yesterday on Megasquirt, no issues.

[hoveringuy]

OBD2=win

OBD2 S50 on a Temp. M52 Flash

Which cat are you running?? I was just as clean on OBD1.

[r4esh]

hoveringuy... sooo the plot thickens: a year ago I when It tried to pass emissions I had the stock obd2 cats and I ran it through with those and the car failed, so I thought maybe something was wrong with those since they had 125k+ miles on them and THAT is when I switched to the Magnaflow High-Flow cats.. So its possible that you're right and the high-flow cats aren't cutting it, but I think there is something else going on.

[Jalves619]

After talking to Giantkeeper I'm not sure they care what size motor is in the car. I haven't been able to find any of my old sheets to compare, but I think those values are just standard values for all vehicles.

DesertBMW | Turbulance on the MAF? Yes the filter is directly on the MAF. You're suggesting that vibration at idle is causing the MAF to receive an incorrect reading and thus give me the score I had?

What DesertBMW is saying is that the MAF requires semi laminar airflow to accurately determine how much air is passing through it. Having the filter attached directly will cause turbulence which can skew MAF readings.

I'm personally thinking tha the tune you have is a bit rich and is whats causing all of these issues. Your numbers barely changed when you switched cats so I'm tempted to rule those out. Do you still have the picture of the results from a year ago? I looked at your old thread but the link was down.

[r4esh]

Jalves619 - Good call man, I think its in the glovebox, so I'll check in the morning for previous scores before swapping the cats.

I'm thinking about adjusting my throttle cable up so that I'm running a idle at like 1k rpm + adding something between MAF and intake filter and running through emissions again. Then I'll just put the throttle cable back down so it idles at what it is now (750 or so rpm). Since the car is passing under load, maybe this would help? Maybe it wouldn't make enough of a difference? Thoughts?

[ian e30 318is]

DesertBMW | Turbulance on the MAF? Yes the filter is directly on the MAF. You're suggesting that vibration at idle is causing the MAF to receive an incorrect reading and thus give me the score I had?[/I]....

Desert BMW is talking about the turbulent air passing over the MAF sensor not the car itself vibrating. He is thinking that the sensor might have trouble reading the amount of air entering the intake because of the turbulent flow of air, but to me it seems that at idle there wouldn't be enough air velocity to produce a turbulent stream.

[328ijunkie]

Jalves619 - Good call man, I think its in the glovebox, so I'll check in the morning for previous scores before swapping the cats.

I'm thinking about adjusting my throttle cable up so that I'm running a idle at like 1k rpm + adding something between MAF and intake filter and running through emissions again. Then I'll just put the throttle cable back down so it idles at what it is now (750 or so rpm). Since the car is passing under load, maybe this would help? Maybe it wouldn't make enough of a difference? Thoughts?

Thats worth a shot but im unsure what the ECU will think of that. Its going to see the TPS is part open and think youre on throttle thus switching away from the idle ECU map.

Desert BMW is talking about the turbulent air passing over the MAF sensor not the car itself vibrating. He is thinking that the sensor might have trouble reading the amount of air entering the intake because of the turbulent flow of air, but to me it seems that at idle there wouldn't be enough air velocity to produce a turbulent stream.

^Also heard this and it makes sense but never seen it really mess things up other than having a intake tube with the MAF clocked wrong.






Also a weird random thought. What about creating a small vac leak? Vac leak=unmetered air=lean running... ? Prob a bad idea but worth a shot.