E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > Tuning & Tech > DIY: Do It Yourself

DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 05-15-2011, 07:25 PM   #1
thefrog1394
Registered User
 
Join Date: Jul 2009
Location: Columbus, Ohio
Posts: 1,007
My Ride: e46- 1999 323i
o2 Simulator circuit DIY

http://www.mkiv.com/techarticles/oxy...sor_simulator/

FYI this o2 simulator circuit fools our computer successfully, just tried it out on my car. For those who don't mind some soldering it can be built for quite a bit cheaper than the o2simulator.com type o2 sims.
__________________

Photo in Cleveland, Ohio
1999 323i - 210,000 miles and counting.
Rear Wheel Bearing Tool (SitTools B90) Rental, ~$60
thefrog1394 is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 05-15-2011, 08:26 PM   #2
aeathb
Registered User
 
Join Date: Sep 2010
Location: Tampa
Posts: 9
My Ride: 2005 bmw 325i
I hope this isn't a bad question, but if you created a circuit to "fool" the ECU into thinking it is using an O2 sensor when its not, wouldn't that make the car run too lean/rich or just less efficient?
aeathb is offline   Reply With Quote
Old 05-15-2011, 08:46 PM   #3
SweTurbo
Big Pimpin'
 
Join Date: Nov 2008
Location: Europe
Posts: 2,899
My Ride: 323i -98
Quote:
Originally Posted by aeathb View Post
I hope this isn't a bad question, but if you created a circuit to "fool" the ECU into thinking it is using an O2 sensor when its not, wouldn't that make the car run too lean/rich or just less efficient?
It's just for the post cat sensors , so that you can run headerless without throwing a CEL / Status not ready.
SweTurbo is offline   Reply With Quote
Old 05-15-2011, 08:47 PM   #4
aeathb
Registered User
 
Join Date: Sep 2010
Location: Tampa
Posts: 9
My Ride: 2005 bmw 325i
I have always wondered what I would do if I put on headers. So they are only for emissions control I take it?
aeathb is offline   Reply With Quote
Old 05-15-2011, 09:14 PM   #5
thefrog1394
Registered User
 
Join Date: Jul 2009
Location: Columbus, Ohio
Posts: 1,007
My Ride: e46- 1999 323i
Quote:
Originally Posted by aeathb View Post
I have always wondered what I would do if I put on headers. So they are only for emissions control I take it?
The only purpose of the post-cat o2 sensor is to detect whether the catalytic converter is functioning properly. This simulates the signal that the o2 sensor would send when the cat is functioning properly. (well simulates it close enough to fool the DME)

And yes, this is for simulation the post-cat o2 sensor only. Simulating a pre-cat o2 sensor would do all kinds of bad.
__________________

Photo in Cleveland, Ohio
1999 323i - 210,000 miles and counting.
Rear Wheel Bearing Tool (SitTools B90) Rental, ~$60

Last edited by thefrog1394; 05-15-2011 at 09:17 PM.
thefrog1394 is offline   Reply With Quote
Old 04-04-2012, 09:55 AM   #6
cposk
Registered User
 
Join Date: Apr 2012
Location: Maryland
Posts: 473
My Ride: 08' E90 M3
Sorry to revive an old thread, but 2 questions for the OP.
Did you use 1/4w resistors? And did you have to simulate the heater circuit or did you leave the o2 sensors plugged in.

I have a month to get my emissions done and this is going to be the cheapest route.
cposk is offline   Reply With Quote
Old 04-09-2012, 04:57 PM   #7
thefrog1394
Registered User
 
Join Date: Jul 2009
Location: Columbus, Ohio
Posts: 1,007
My Ride: e46- 1999 323i
I do not recall what the power rating on the resistors was that I used, but the signal lines don't carry much power so 1/4 watt should be fine I would imagine. And yes I just used the old sensor's heater instead of simulating a heater circuit
__________________

Photo in Cleveland, Ohio
1999 323i - 210,000 miles and counting.
Rear Wheel Bearing Tool (SitTools B90) Rental, ~$60
thefrog1394 is offline   Reply With Quote
Old 05-21-2012, 10:27 AM   #8
Mark M
Registered User
 
Join Date: Sep 2009
Location: Lancaster, PA
Posts: 420
My Ride: e30 M3 / e90 335d
I just used the MKIV link this weekend and soldered up the circuit. Installed it yesterday. Fingers crossed...hoping the Check Engine light will finally stay off.
__________________
Mark M is offline   Reply With Quote
Old 05-21-2012, 10:50 AM   #9
jbeurotech
Regional Sponsor
 
Join Date: Aug 2006
Location: New Brighton MN
Posts: 5,019
My Ride: 2000 E46 with 254K
Quote:
Originally Posted by thefrog1394 View Post
The only purpose of the post-cat o2 sensor is to detect whether the catalytic converter is functioning properly. This simulates the signal that the o2 sensor would send when the cat is functioning properly. (well simulates it close enough to fool the DME)

And yes, this is for simulation the post-cat o2 sensor only. Simulating a pre-cat o2 sensor would do all kinds of bad.
Post cat o2's DO also do fuel mixture control.


You are incorrect I have posted it a few times let me try to find the post.


here it is


Here you go straight from BMW's trianing manuel puts any agruments to bed LOL

POST CATALYTIC CONVERTER SENSOR SIGNAL
The post catalyst O2 sensors monitor the efficiency of the catalyst as a requirement of OBD
II. This signal also provides feedback of the pre-catalyst sensors efficiency and can cause
the ECM to "trim" the ms injection time to correct for slight deviations.
Bosh Systems:
If the catalyst is operating efficiently, most of the
remaining oxygen in the exhaust gas is burned
(lack of O2 - "constant lean signal***8221.
The sensor signal fluctuates slightly in the higher
end of the voltage scale.
If the post sensor shows excessive fluctuations
(which echo the scope pattern of the pre sensor),
this indicates that the catalytic converter is not
functioning correctly and cannot consume the O2
(fault set).
If the post sensor fluctuations move out of the normal voltage "window", this indicates
that the pre sensor is not performing properly due to slight deterioration. These systems
can also "trim" the ms injection time to compensate for this.
The constantly changing oxygen sensor input to the ECM is needed to correct the ms
injection time to ensure that the ideal air/fuel ratio is maintained.
20
Engine Management Systems
__________________

Seth Thorson
Service Manager/BMW Tech
JB Eurotech Service "Your Reasonable Dealer Alternative"

General Questions can be sent to appointment@jbeurotech.com

1. Do not argue with an idiot. He will drag you down to his level and beat you with experience.
2. Light travels faster than sound. This is why some people appear bright until you hear them speak.

Last edited by jbeurotech; 05-21-2012 at 10:55 AM.
jbeurotech is offline   Reply With Quote
Old 07-16-2012, 02:04 PM   #10
thefrog1394
Registered User
 
Join Date: Jul 2009
Location: Columbus, Ohio
Posts: 1,007
My Ride: e46- 1999 323i
Interesting, though sounds to me like they only really have an effect if the pre-cat sensor is starting to deteriorate.

Anyways I've not had an issue running without my own post-cat sensor. No gas mileage issues or anything else.
__________________

Photo in Cleveland, Ohio
1999 323i - 210,000 miles and counting.
Rear Wheel Bearing Tool (SitTools B90) Rental, ~$60
thefrog1394 is offline   Reply With Quote
Old 07-16-2012, 04:52 PM   #11
joshzhp
Registered User
 
Join Date: Feb 2008
Location: CA
Posts: 289
My Ride: ZHP--Stock
I remember a post about the signal output changing...will this work on an 2003 model?
joshzhp is offline   Reply With Quote
Old 07-22-2012, 08:53 AM   #12
wildcat293
Registered User
 
Join Date: Mar 2009
Location: Rochester, NY
Posts: 190
My Ride: 325xi
Quote:
Originally Posted by thefrog1394 View Post
Interesting, though sounds to me like they only really have an effect if the pre-cat sensor is starting to deteriorate.
I think that sounds right. As long as the simulator makes the ECU think the post cat is working properly, nothing is tuned/detuned.
wildcat293 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 12:01 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use