Turbo__Tim
One heck of a Tim!
- Joined
- May 25, 2001
- Messages
- 640
I was just wondering how your readings were affected by the introduction of alchy...
Anyone using a wide band sensor, and alchy?
- Thread starter Turbo__Tim
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You shouldn't notice any difference. In closed loop, your computer should back out some fuel to reach the target A/F ratio depending on how much Alc your using. All the way to running nothing but alcohol you would read the O2 exactly as you would with gas.
I'm wondering, how quicly does it react? If you shoot say 20% of your total fueling as alcohol, how long will it take for the car to bring the A/F ratio in? I know you would have to set the maximum correction limit much higher than those who don't run alky.
Don, how does the Electromotive keep the proper A/F without a wide band? I asked the tech guys at Electromotive and the only answer I got was "we know something the other guys do not".
Sounded like a BS answer at the time, so I dismissed it. Now I am wondering if they were not FOS like I thought. ERIC.
Sounded like a BS answer at the time, so I dismissed it. Now I am wondering if they were not FOS like I thought. ERIC.I have had other engine tuners tell me that it's impossible to get the A/F tuning good enough with a regular O2 sensor. With all the tuning I have been doing with my engine, going from the 15s at times to in the 10s I haven't seen why I would need to switch to a wide band sensor. I'm told that the regular O2 is less sensitive at the lean and rich ends of the spectrum. My thinking is, it may be less sensitive, but if the system is designed to understand the changes in voltage at the ends of the spectrum even if less than at stoich then I don't see a problem. There IS A CHANGE in voltage at the ends and it may be small as compared to the stoich section, but if the system still understands that at the rich end a change of this much means this A/F ratio, I'm fine with that. If there was no change at all between say 12 or 11 to one and 10 to one, then I would understand why a wide band would be necessary. I suspect a wide band just gives you finer definition at the ends of the spectrum to play with. That may be something that the indy guys need to suck every last bit of HP out of the motor, but for what I am doing and considering that alcohol is so forgiving as far as the mixture goes, I just don't think I need it. The regular sensor has demonstrated to me that if I make a SMALL mixture change, I WILL see it on the data stream. That's all I can ask for.
And, they are right.
I had my GN running at about820 mv.
Close right?.
Stuck a WB in and it was 12.5:1
Plugs were fine (been reading plugs for like 30+ years).
And performance was good.
Just for grins dialed in a little more fuel, and was at 12.2, and the car started turning anumal.
Added some more fuel got it down to 11.8, and the car was in a full animal mode. Even dropped the EGT enough to be an animal with 2 PSI less boost.
Total change on the stock WB,
I went from 820 to 840.
The oem sensors are sensitive to EGT, and backpressure.
The exhaust gases are just under super sonic, and you have just a couple feet for the change in O2 levels to change. Oh, by the way you can individually trace cylinder by cylinder up to about 3,500 rpm if you have the right equipment with a WB.
WWW.DIY-WB.COM
For the American Original DIY-WB.
The Electromotive system has a table that allows you to adjust the O2 sensor outputs (voltages) to the A/F readings that the system will translate them to on your monitor or data captures. It comes preset for the sensor they supply. Using the O2 sensor that they supplied, I'm sure the table was dialed in to that sensor model. When I started going to the over rich side, the power decreased and the A/F readings were reasonably what I would of expected them to be. Actually, to me the A/F number was not as important as being able to see how much of a change occured when I tweaked the mixture. It seemed sensitive enough for me. At no time did I make a change to mixture and not see it show up on the A/F ratio graph no matter how small the change was. What ultimately tells you what A/F number is best for your rig is the time slip. EGT and plug readings too if your worried about things lasting. The A/F number on the screen only becomes a reference to judge future adjustments against. Just like your time slip. I have a feeling the number could be off by one and just as long as your able to use that number as a reference to changes that you make, good or bad, then what the hell. Now if you had an engine builder that told you that with my motor you must run 12.2 to one to get the best performance from my motor, then I can see why you would want the most accurate setup possible, but If you guys are like me I would still wonder up and down from that number anyway to see if there was a little extra to be found.
I don't think that what Bruce and Don are saying is really all that different.
On this BB, Bruce has never said that one must tune to a particular AFR number. In his posts on building the DIY WB, he has said that you still must know how to read plugs - i.e, use the basics to interpret what the tool tells you. Don's saying the numbers (timeslip) tell the story when making changes to AFR. Again, using the basics to determine which numbers work best, not "this AFR must be attained."
I'm far from a guru, but two things occur to me:
* The Electromotive system is a far cry from an OEM TR computer, so it could very well be fine with no WB O2.
* Adding a WB O2 could show you that you were way far off from optimum, or it could show you that you were spot on with the narrow band. That would be a tribute your skill as a tuner, not an indictment of a WB O2...
Me, I want a WB O2.
On this BB, Bruce has never said that one must tune to a particular AFR number. In his posts on building the DIY WB, he has said that you still must know how to read plugs - i.e, use the basics to interpret what the tool tells you. Don's saying the numbers (timeslip) tell the story when making changes to AFR. Again, using the basics to determine which numbers work best, not "this AFR must be attained."
I'm far from a guru, but two things occur to me:
* The Electromotive system is a far cry from an OEM TR computer, so it could very well be fine with no WB O2.
* Adding a WB O2 could show you that you were way far off from optimum, or it could show you that you were spot on with the narrow band. That would be a tribute your skill as a tuner, not an indictment of a WB O2...
Me, I want a WB O2.
If your doing you tuning at the strip, or with some sort of timing devise, it's all mute about what unit of measuerment you use to guage your performance. On that I will agree with you.
But,
With a WB the resolution is many times greater so you can with greater accuracy develope a repeatable basic tune.
I can say, That I actually saw what I saw, and it would have taken alot more passes to deal the car then it did.
There is just no substitute for something like a Translator Plus and a WB.
I'm not disputing that some systems may be more tunable with a WB. It's just that with the smallest adjustment to mixture that the TEC II allows me to make, I can note the results with a regular O2. For that reason, I have never seen the need to use a WB. Maybe, I've just grown accustomed to tuning with the little bit of resolution I have. I haven't tuned with other systems including the stock one so I don't have anything to compare to. Also, unless those things have come down in price since the last time I checked, they're darn expensive. Although, If your setup requires you to have one, it will definitely pay for itself.
Well, the best setup is one your comfortable with.
If I just might point out.
A single wire O2 sensor has no temp compensation. The EGT is what heats it to a working temp., and the temp varies. Heat is part of the chemical reaction, vary the heat and the reaction changes, granted not a huge amount, but personally I don't want to put too much risk into it.
Then we have a heated stock sensor. Well, it heats up enough to work, ie about 600dF. And again when you consider the EGT is 700dF or so, then it will again have a EGT error.
Enter the WB, in addition to a somewhat linear output, and a larger range (0-5v), it's heater warms it up to 800dC (not a typo). So there is only an EGT temp error at the stage your about to melt the motor down.
While you see a change, fine, but how much is fuel and how much is EGT change?.
In richening mine up I wound up dropping the EGT and boost, and was able to see where I still was AFR wise.
It would almost be interesting to see how fine of line the Electrmotive allows in tuning. If the steps are large then you will see changes, but you might be 1/2 a notch off from best.
The TEC system allows me to make as small as a 1% PW correction at any user predefined rpm x map point in a volumetric efficiency table. It can be adjusted even finer by playing with the basic fuel curve in 2 ways. TOG and IOT. I have never needed any finer adjustment than what the VE table gives me. A 1% PW change is very noticeable with this system. To tell you how reactive the system is, I was spraying additional fuel on the top end through some archaic spray bars that were controlled by a nitrous fuel solenoid. The TEC controlled when the solenoid would energize. I chose to run in open loop and let the TEC guide me to the corrections I would need. A safer way would of been to run in closed loop and monitor the amount of correction that was made and then adjust the VE table to more closely match. That method is available and I did use it a little when working with gasoiline, but I chose to make very small steps with the alcohol. The data was captured at a rate of one frame every .05 seconds or there abouts. Just one example that I pulled up quickly was a change in the O2 voltage from 3.78 to 2.41 to 3.43 within .1 seconds. I know even .05 seconds is eternity to an engine, but do you really need quicker and more resolute a response? Seriously, I don't have a ton of experience tuning with electronic systems and would be interested in knowing how quick the response needs to be and what the capture speed is on other comparable systems.
