Exhaust Experiments & Air Fuel Ratio - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 12-21-2007, 07:55 PM   #1
Registered Member
 
Join Date: Oct 2007
Posts: 28
Country: United States
Exhaust Experiments & Air Fuel Ratio

I did an unconventional experiment when I accidentally broke my exhaust nuts & couldn't screw the pipe on. This led me to drive 360 miles without a midpipe, cat & muffler.

The result was the best gas mileage ever. I drove 330 miles before the gas light came on. My previous best was 315.

I put on a highflow cat but took it off because it had a severe drop in mileage. But when I take the whole thing off my mileage goes up..hmm so now its time to tamper with the 2nd O2 sensor.

Its something I don't want to duplicate again but it led me to do to 2 different tests to try out.
The problem with my car is if u lean the fuel too much the 2nd O2 sensor picks it up because theres no gas to burn in the cat. Its all got burned in the more efficient A/F ratio. The 2nd sensor mimics the first sensor & inefficient CAT cel (p0420) is given robbing mileage again

1. O2 Simulator - Trick the 2nd O2 sensor to thinking everything is normal.
http://www.mkiv.com/techarticles/oxy...sor_simulator/

2. O2 Sensor Deadzone - A O2 Sensor that isn't in direct exhaust airflow fluctuates different than the first one in direct airflow.
http://www.k-series.com/forum/showthread.php?t=8833

Im going with the $5 option 2 mod first to see if it gives me more control of the air fuel ration w/o making the CAT mad.

Anyone else dont similar tests?
__________________

ProtonXX is offline   Reply With Quote
Old 12-23-2007, 02:35 AM   #2
Registered Member
 
ZugyNA's Avatar
 
Join Date: May 2006
Posts: 587
Country: United States
You can buy an EFIE for around $60-70.

An O2 sensor cycles around 1Xs per second..maybe a little longer? Info usually in the FSM. Cycling too slow is called a "lazy" sensor...sign that it needs replacing.
__________________

__________________
Leading the perpetually ignorant and uninformed into the light of scientific knowledge. Did I really say that?

a new policy....I intend to ignore the nescient...a waste of time and energy.
ZugyNA is offline   Reply With Quote
Old 12-23-2007, 09:50 AM   #3
Registered Member
 
kamesama980's Avatar
 
Join Date: Nov 2007
Posts: 742
Country: United States
Location: Columbus, IN, USA
Send a message via AIM to kamesama980 Send a message via Yahoo to kamesama980
exhaust selection depends on the car and what exhaust you're putting on. a properly sized free flowing system will have little difference. the stock system tuned for quietness will make some difference, a cheap replacement system will make a big difference.

As for the engine, it depends on the manifold design and how the engine's designed. I had an infiniti G20 that broke the exhaust off before the cat and while highway/high rpm power and mileage was great, you coudln't drive the car under 3k rpms (not that it minded) put the exhaust back on and BOOM, chirp the tires at 2k and accelerating it tops out around 6500 rpm and gets great mileage in town, 1-2 less on the highway
__________________
-Russell
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
mechanic, carpenter, stagehand, rigger, and know-it-all smartass
"You don't get to judge me for how I fix what you break"
kamesama980 is offline   Reply With Quote
Old 12-23-2007, 12:02 PM   #4
Registered Member
 
Join Date: Oct 2007
Posts: 28
Country: United States
I have a EFIE & A/F Gauge already. The problem is the EFIE lowers the ratio for about a few minutes. Then AF ratio goes back up. Im burning all the fuel before it hits the cat, then the 2nd O2 sensor pics it up and either throws a 420 or re adjust the ratio .
ProtonXX is offline   Reply With Quote
Old 12-25-2007, 04:54 AM   #5
Registered Member
 
ZugyNA's Avatar
 
Join Date: May 2006
Posts: 587
Country: United States
Quote:
Originally Posted by ProtonXX View Post
I have a EFIE & A/F Gauge already. The problem is the EFIE lowers the ratio for about a few minutes. Then AF ratio goes back up. Im burning all the fuel before it hits the cat, then the 2nd O2 sensor pics it up and either throws a 420 or re adjust the ratio .
Aren't you supposed to put the EFIE on the second sensor?
__________________
Leading the perpetually ignorant and uninformed into the light of scientific knowledge. Did I really say that?

a new policy....I intend to ignore the nescient...a waste of time and energy.
ZugyNA is offline   Reply With Quote
Old 12-25-2007, 11:53 PM   #6
Supporting Member
 
cfg83's Avatar
 
Join Date: Sep 2006
Posts: 1,779
Country: United States
ZugyNA -

Quote:
Originally Posted by ZugyNA View Post
Aren't you supposed to put the EFIE on the second sensor?
I don't think so. That was not my understanding when I installed mine :

Eagle Research EFIE Online ...
http://www.gassavers.org/showthread.php?t=5036

I think that older cars have only one 02 sensor (pre-OBDII?!?!?!) in the exhaust manifold, so it works better with them. On my car, I think the EFIE works because I can *see* the A/F ratio go lean. My observation is that it cycles up to lean and back down to normal (see post above). I do think that the better setup is an EFIE for each sensor, but I only have one EFIE effecting the exhaust manifold 02 sensor.

Right now I am disabling the EFIE to see what my long term MPG is without it.

CarloSW2
__________________
Old School SW2 EPA ... New School Civic EPA :

What's your EPA MPG? http://www.fueleconomy.gov/feg/calculatorSelectYear.jsp
cfg83 is offline   Reply With Quote
Old 12-26-2007, 04:53 AM   #7
Registered Member
 
ZugyNA's Avatar
 
Join Date: May 2006
Posts: 587
Country: United States
Well....if the second O2 has the final say...it's possible that using the EFIE on it would work? Using it there would tell the ECU that the mix was too rich and over ride the first O2?
__________________
Leading the perpetually ignorant and uninformed into the light of scientific knowledge. Did I really say that?

a new policy....I intend to ignore the nescient...a waste of time and energy.
ZugyNA is offline   Reply With Quote
Old 12-26-2007, 11:22 AM   #8
Registered Member
 
Join Date: Nov 2007
Posts: 25
Interesting.
__________________
GasSavers_broadwayline is offline   Reply With Quote
Old 12-26-2007, 01:36 PM   #9
Supporting Member
 
cfg83's Avatar
 
Join Date: Sep 2006
Posts: 1,779
Country: United States
ZugyNA -

Quote:
Originally Posted by ZugyNA View Post
Well....if the second O2 has the final say...it's possible that using the EFIE on it would work? Using it there would tell the ECU that the mix was too rich and over ride the first O2?
I think that having an EFIE on both 02 sensors would be best. In terms of dominance, everything I have read about "closed loop" operation implies (to me) that the 02 sensor in the exhaust manifold is the one that is primarily used by the ECU/PCM. The second 02 sensor (again, from what I have read), is helping to maintain the health and efficiency of the catalytic converter.

Hrmmmmmmmm ...

Hypothesis : At least one 02 sensor is needed for closed loop operation.
Test #1 : Disconnect first 02 sensor and see if car is able to go into closed loop operation. Note OBDII error codes. Reconnect sensor. Clear error codes.
Test #2 : Disconnect second 02 sensor and see if car is able to go into closed loop operation. Note OBDII error codes. Reconnect sensor. Clear error codes.

For each test, a failure to enter closed loop implies that the ECU/PCM depends on that sensor for closed-loop operation. If both tests fail to enter closed loop, then both sensors are absolutely necessary for closed loop operation.

Here is another thread by XFi on the same subject :

Just ordered an EFIE - BrightGreen FeverBuster
http://www.gassavers.org/showthread.php?t=4894

I think that someone around here (XFi?!??!) was going to install an EFIE on both 02 sensors, but I can't remember who.

CarloSW2
__________________
Old School SW2 EPA ... New School Civic EPA :

What's your EPA MPG? http://www.fueleconomy.gov/feg/calculatorSelectYear.jsp
cfg83 is offline   Reply With Quote
Old 12-27-2007, 05:20 AM   #10
Registered Member
 
ZugyNA's Avatar
 
Join Date: May 2006
Posts: 587
Country: United States
A lot of it depends on the particular ECU (vehicle) that you are working with? I've read of people having problems with double O2 Dodge trucks...where the ECU over rode anything they tried.

I'd try it on the second O2....though you might get a code if the ECU starts to think the first O2 or whatever is faulty.

I ran an EFIE on a 3 wire O2 '87 Nissan using around 200 mas. Found that the temp sensitivity was to my advantage since the mas increased with temp...allowing a little richer operation when cold. Found it was best to find a place in the cabin that was down low...away from sun and heater/AC flow to get an ambient temp.

The main gains from an EFIE are supposed to come from using them WITH something like acetone or fuel heat....though it's a good idea to get the ECU to cooperate with the EFIE first?
__________________

__________________
Leading the perpetually ignorant and uninformed into the light of scientific knowledge. Did I really say that?

a new policy....I intend to ignore the nescient...a waste of time and energy.
ZugyNA is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
wont let me enter a fuel up :( Joloke Fuelly Web Support and Community News 4 10-29-2009 07:19 AM
Make / Model/ Year averages jeadly Fuelly Web Support and Community News 1 08-15-2008 12:02 AM
Turbo FE? Wyldesoul General Fuel Topics 30 07-01-2007 05:24 PM
Air Dam or Belly Pan tor07 Aerodynamics 10 04-07-2007 12:17 PM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 07:47 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.