waterinjection.info  

Go Back   waterinjection.info > Injection Theory (what it is and what it does) > In Cylinder Effects

Reply
 
Thread Tools Display Modes
  #1  
Old 13-11-2003, 07:20 PM
Forum Admin Forum Admin is offline
Senior Member
 
Join Date: Oct 2003
Posts: 127
Default How are you calibrating / adjusting for water injection AFR?

The injection of water and alcohol mixes in the induction system will dilute the exhaust and alter the partial pressures being measured by wide band lambda sensors.

I have not been able to nail down the exact degree or amount of potential error - though feed back would suggest that a meter would read leaner than the actual induction mix is.

Has anyone calibrated or otherwise adjusted their readings for water injection?
__________________
Forumadmin
Forumadmin@waterinjection.info
Reply With Quote
  #2  
Old 22-11-2003, 05:45 AM
willwren willwren is offline
Junior Member
 
Join Date: Nov 2003
Location: Albany, OR
Posts: 9
Default

I never felt the need to. My aftermarket chip seems to have made enough of an adjustment to my MAF readings to make up for the small amount I was injecting.

As I get my new system going, I'll be watching my AFR like a hawk. My solution, should I need one, will probably be the ZZP Mini-AFC controller.
__________________
Administrator, The Bonneville Club http://www.bonnevilleclub.com/
http://home.comcast.net/~bonnevilleclub/sig.jpg
Reply With Quote
  #3  
Old 24-11-2003, 12:28 PM
Philip Philip is offline
Member
 
Join Date: Nov 2003
Location: UK
Posts: 31
Default

Hi,
when I eventually get my engine blown Im going to keep the water off whilst tuning, retard ignition to help avoid deternation during boost. Then turn the water on and see what happens to the AFR from my WB sensor. Will let you know how much it changes. Ive programmed the ecu to turn off lambda correction during water injection, but do you think the readings will be constant? What I mean is if I find out what the AFR is when water is on can I set that as my target or will it vary due to things I haven't thought of like temperature, etc?
Phil
__________________
http://www.replica-cobra.co.uk
Reply With Quote
  #4  
Old 24-11-2003, 11:35 PM
AKWRX AKWRX is offline
Member
 
Join Date: Oct 2003
Location: Juneau, Alaska
Posts: 32
Default

Quote:
Originally Posted by Philip
What I mean is if I find out what the AFR is when water is on can I set that as my target or will it vary due to things I haven't thought of like temperature, etc? Phil
Using the "conventional wisdom" tuning to a target AFR when injecting alcohol, or a water mix does indeed introduce all kinds of new variables. The oxygen sensor data via either A/F, or Lambda units, is affected by many new unknowns. Determining a target A/F ratio in advance of the tuning process may be beyond just difficult. After wrestling with this issue for some time (until my head hurts from reading), the complexities are more than I would like to tackle.

So, my approach will be a more practical, proven path to tune directly from real time peak cylinder pressure, and adjust its position in the power stroke with the iginition timing. The optimum A/F ratio should essentially just fall out by default. It is an "end run" way to figure out the best A/F ratio. From that point, A/F will just be used to monitor the tune for safety purposes only. The techique is well established (Formula 1, Indy, NASCAR, top fuel dragsters, etc.), only the hardware is very, very expensive. Once I can afford the $1250 pressure sensor (spark plug integrated), a DIY system may be able to be put together for about $2K total cost. Anyhow, that's the plan...
Reply With Quote
  #5  
Old 25-11-2003, 02:12 AM
Forum Admin Forum Admin is offline
Senior Member
 
Join Date: Oct 2003
Posts: 127
Default

Alternative fuels will definitely move the reference point for sensors calibrated to gasoline.

Additional steam in the exhaust will mess with diluted partial pressures.

I have been corresponding with someone that understands the impact very well - but that does not make it measurable. He basically said that anytime you are really relying a lambda you should calibrate it, the best way to do so is with a gas analyzer. Of course that only works with catless systems.

As I thought about this I was talking to someone about the idea of using water injection eliminating unburned hydrocarbons from the induction charge. And I started wondering about skipping the lambda sensor and just using a gas analyzer. Theorectically, with water injection I want to tune right to the point where the CO is minimized - that should be the maximum power mixture. The person I was talking with mentioned not to my surprise that there are quite a few performance tuners who tune to CO rather than lambda settings for any number of reasons but they find it quite accurate for what they seek to do.

I might realize some things on my own some times but rarely will I have been the first to realize it.
__________________
Forumadmin
Forumadmin@waterinjection.info
Reply With Quote
  #6  
Old 25-11-2003, 09:49 AM
Philip Philip is offline
Member
 
Join Date: Nov 2003
Location: UK
Posts: 31
Default

Hi,
So is it OK to tune the AFR with the water off using the WB Lambda, then turn the water on and then dont use the Lambda sensor for AFR correction while water is on? That was my original plan, or do I need to use a gas analizer to retune when water is on?
Phil
__________________
http://www.replica-cobra.co.uk
Reply With Quote
  #7  
Old 28-11-2003, 11:14 PM
Sato Sato is offline
Junior Member
 
Join Date: Nov 2003
Posts: 20
Default

Quote:
Originally Posted by Philip
Hi,
So is it OK to tune the AFR with the water off using the WB Lambda, then turn the water on and then dont use the Lambda sensor for AFR correction while water is on? That was my original plan, or do I need to use a gas analizer to retune when water is on?
Phil
Please forgive my ignorance but couldn't you get just as good results by monitoring the EGT's closely and use a scanner to see if timing is being pulled by unheard detonationby the computer? I understand that air fuel ratio is a good tool but you can detonate still even if your in a so called safe zone because of poor fuel,,high ambient temps etc.
I would think that knowing when detonation happens would dictate any setup's variables,,timing/fuel,water jet size,etc. I have a AFR guage;not the kind you speak of though but it's the last thing I check after EGT's and knock with a scanner. Fill me in on this sensor
Sato
Reply With Quote
  #8  
Old 29-11-2003, 04:32 AM
AKWRX AKWRX is offline
Member
 
Join Date: Oct 2003
Location: Juneau, Alaska
Posts: 32
Default

Tuning from EGT does not work that well once you are injecting water, or alcohol, and are taking advantage of the more agressive ignition advance injection allows because of the higher knock threshold. As ignition is advanced, EGTs will always decrease (without any other tuning changes), because the cylinder combustion process simply has more time to be more complete before the exhaust valve opens. EGT is better used as a reference point for A/F changes, and as a safety monitoring input after everything is tuned.
Reply With Quote
  #9  
Old 29-11-2003, 06:27 AM
Sato Sato is offline
Junior Member
 
Join Date: Nov 2003
Posts: 20
Default

Quote:
Originally Posted by AKWRX
Tuning from EGT does not work that well once you are injecting water, or alcohol, and are taking advantage of the more agressive ignition advance injection allows because of the higher knock threshold. As ignition is advanced, EGTs will always decrease (without any other tuning changes), because the cylinder combustion process simply has more time to be more complete before the exhaust valve opens. EGT is better used as a reference point for A/F changes, and as a safety monitoring input after everything is tuned.
In my application more advance simply brought on detonation on my scanner AT THE DYNO] WHAT IS INGNITION ADVANCE INJECTION?
Ingition[too much]advance WILL cause an increase in egt's if it it's advanced enough! As will retarded base timing!
EGT's can go up from too much advance as well as to little advance!!
I have heard of guy's advancing the timing too much and blowing up their engines,,,and it ain't cause the egt's went down. YOU CAN DETONATE WITH TOO RICH A MIXTURE ALSO!!!l ALWAYS DECREASE EGT'S WITH MORE ADVANCE IS VERY INCORRECT!
You have not told me why this AFR is the way to go with this new sensor.
So far I do not agree. You can waste a motor at low throttle and boost if the conditions are not corect LIKE LATE OR EARLY TIMING WITH THE INCORRECT FUEL RATIO AND IF SEVERE ENOUGH IT WILL DO IN THE MOTOR INSHORT ORDER
I still feel that the REAL SENSOR IS THE KNOCK SENSOR,,,AS YOU CAN TALK ALL YOU WANT AND DO ALL YOU WANT BUT IF THE FRICKEN THING DETONATES ON A SCANER BEFORE YOU HEAR IT ,,,,THAT IS THE DETERMINING FACTOR.
I DON'T CARE WHAT AFR SENSOR YOU GOT PLACED ANYWHERE,,IF IT DETONATES YOU GOT A PROBLEM.
SATO
Reply With Quote
  #10  
Old 29-11-2003, 07:39 AM
Sato Sato is offline
Junior Member
 
Join Date: Nov 2003
Posts: 20
Default

One last thing, if the AFR read ok at a given rpm./boost //advance //etc
BUT, my scanner showed that the computer sensed detonation and pulled 10 degrees of timing out of cylinder#1 ,,6 degrees out of cylinder 3 and less in the other two cylinders........what sensor would you believe?
This has happened to me and others and I'm sure many others that don't even know it because they don't have a scanner. They just use a cheap i will admit AFR sensor with a stock O2 sensor[4 wire],,but it reads rich.
Many don'y understand that if you know when knock happens and how much timing is being pulled ,,you could run alot less boost and make alot more HP!!! When detonation is sensed by the computer it takes ALOT of ingition retard and time to remove it . By then the race could be over!!\
The whole purpose in my mind is to never have the computer remove ANY timing at ANY time. Once it does you have comprimised the whole performance aspect of the car. And without the proper info[like a computer scanner to read the cars brain] most will never know it and perhaps add more boost or timing because they haven't HEARD any detonation and all the while the computer is retarding the timing BIG TIME to save the motor
Please fill me in on this AFR sensor,,,what the hell does it do excactly? And how is it more informative than a knock sensor as far as the bottom line goes?
Thanks,
Sato
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

Forum Jump


All times are GMT +1. The time now is 07:24 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.