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M635 and CA Smog cert

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philm635
Posts: 6
Joined: Wed Jun 02, 2010 5:20 am
Location: Pleasant Hill CA.

M635 and CA Smog cert

Post by philm635 » Fri Aug 10, 2018 12:19 am

Has anyone been able to pass the California Smog check with a stock federalized M635?
Just curious if it is possible before I throw a bunch of $ at it.
Thanks!
Phil
'85M635

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philm635
Posts: 6
Joined: Wed Jun 02, 2010 5:20 am
Location: Pleasant Hill CA.

Re: M635 and CA Smog cert

Post by philm635 » Sat Aug 18, 2018 1:13 am

I'm told to get an 079 ecu. I assume that would be one from a USA version M6??? Anyone have an extra or recommend a source?
Thx
Phil
'85M635

motroman
Posts: 12
Joined: Sun Oct 22, 2017 4:10 pm
Location: San Francisco

Re: M635 and CA Smog cert

Post by motroman » Sat Aug 18, 2018 1:59 pm

Does "Federalized" cats were installed with corresponding software update to the ECU?
1989 635csi

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philm635
Posts: 6
Joined: Wed Jun 02, 2010 5:20 am
Location: Pleasant Hill CA.

Re: M635 and CA Smog cert

Post by philm635 » Tue Aug 21, 2018 12:22 am

The gray market Federalized M88/3 engines have a cat and O2 sensor installed. The ECU is not reprogrammed but there is an external "Johnson box" circuit installed that uses the O2 sensor input to try and keep the fuel mix at stochiometric level. I found it works poorly forcing the engine to respond to off idle transition with flat spots and lugs and surges at higher speeds. So now I'm trying to find an 079 ecu that has the O2 feedback loop built in.
'85M635

derrith
Posts: 1
Joined: Fri Jun 07, 2013 2:12 am
Location: Bay Area, CA

Re: M635 and CA Smog cert

Post by derrith » Sun Sep 16, 2018 6:32 am

I’ve gotten several m88s through CA smog in the Bay Area using a resistor in line on the coolant temperature sensor. It richens up the mixture on the 055 enough that the NOx levels drop enough to pass on the rollers. Remove after smog, as vehicle will not run great. I have used the 560 ohm. Also works great on 061 10:1 m30s

“BMW Technical Service Bulletin # 13 07 86 Install an external resistor in the wire for the temperature sensor that feeds the Motronics (should be the one with the light grey connector) Resistor type is 270 ohm, 1/2 watt, "Gold Band" metal film resistor for Motronics Control Units with a Bosch code date of 342 or higher (production date after 9/83) and for Motronics 341 and lower (9/81-9/83 production dates), it is a 560 ohm, 1/2 watt "Gold Band" metal film resistor .”
1988 M5
1988 535i

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