HEY guys looking to buy a wideband and im lost at reading, can anybody tell me how to read this 10:1 and 12:4 and all that thanks lol i have a narrow band that i was told now its the apexi turbo timer with a/f so help

 

10:1 means 10 parts air 1 part fuel. It is the ratio of air to fuel. 10:1 is more rich then say 12:1. You would not see a ratio like 12:4 unless you were running 3:1 (heh). My car is happy under boost in the low 11s (11.0:1 - 11.5:1). Typically you get more rich as you increase boost. Under vac. I tune for the mid 13s (13.5:1 to 13.8:1). At idle I like as close to 14.7:1 as I can get with out having to run excessive ignition.

Good luck.

 

If your logged AFR is XXX, and you want to run YYY, change your fuel to:
(XXX / YYY).

Example:
You record 11.5AFRS for part of your map. You want to run 11.0AFRs.

11.5/11 = 1.0454545454 or 1.05 rounded up. That means you need to add 5% more fuel.

 

Makes perfect sense, what engine management do you have, and how close does that generally get you? Thanks, Carl

 

so are you saying at WOT i want to be as close to 14.7 as i can
what does it mean when my narrow band says 20 something maybe im reading the worng thing,
what wide bands are you guys running

 

is a EGR gauge needed if i have a wide band

thanks

 

you shouldent be tuning a car at this point. read up on tuning, their is a plethora of info on this site about it.

also im not quite sure what your trying to say, do you actually have a wideband?

 

EGT gauge maybe?

no, a egt gauge is if you want to know how hot your exhaust gasses are.

a wideband oxygen sensor setup lets you know how much fuel compaired to how much air you are running.

completely seperate sensor setups, both give similar information. wideband is the more accurate tool for tuning.

 

that dosent work exactly, a conversion like that would depend heavily on injector size, and would change as boost changes, or injectors are changed.

eg:

5% on a 1680cc injector is a hell of a lot more fuel then 5% on a 850cc injector.

 

sorry guys i meant EGT,
no im not trying to tune my car i was just told that its good to have one
thanks XS thats what i was trying to find out i knew that its was kinda close but the wide is more accurate

 

just for fun-- since someone brought up getting richer as the boost increases... or you can get richer as rpm's increase also.

this dyno sheet is more or less typical.
that car ended up getting a little more fine tuning, but you can see the general slope going in the downward direction.

fyi, it wouldn't hold boost, so that's what the up n down "rainbow: torque curve was all about.

 

It's just 5% more than the amount injected to get the previous AFR reading, so the size of the injector doesn't matter.

-Max

 

yeah but 5% more on an injector isnt going to directly relate to a cars afr because of variables like injector size, ect.


the formula used was based on air fuel ratio, but it dosent work in all, if any applications because of other variables.

 

+5% will increase the time the injector is open by 5%, so, since the existing reading was derived from the same injectors, increasiung injection duration by 5% should increase fuel by 5%... Am I missing something???

Yes, you are injecting more fuel if you have 1680s, vs 850s, but 5% is 5% no matter what the value being modified.

 

XS, I suspect you are thinking this:

850cc injector at 70% duty cycle gives 595cc to get 11.5 AFR
+ 5% absolute duty cycle
-------
850cc injector at 75% duty cycle gives 638cc, a delta of 43cc (+7.2%)
(with an AFR of about 10.7)

AND

1680cc injector at 35.4% duty cycle gives 595cc to get 11.5 AFR
+ 5% absolute duty cycle
--------
1680cc injector at 40.4% duty cycle gives 679cc, a delta of 84cc (+14.1%)
(with an AFR of about 10.1)


But Carl is talking about adding 5% of fuel, not 5% of absolute duty cycle (two very different things). To add 5%, you could enter 1.05 in the PFC injection correction map, or change the base map by adding 5% to the value that was in the cell when you recorded the 11.5 AFR. The duty cycle you will get with these changes will be 1.05 times the old duty cycle (+5%, but not 5 percent higher duty cycle, see examples below). Here's how it works out:

850cc injector at 70% duty cycle gives 595cc to get 11.5 AFR
+ 5% fuel
-------
850cc injector at 73.5% duty cycle gives 625cc, a delta of 30cc (+5%)
(with an AFR of about 11.0)

AND

1680cc injector at 35.4% duty cycle gives 595cc to get 11.5 AFR
+ 5% fuel
--------
1680cc injector at 37.17% duty cycle gives 625cc, a delta of 30cc (+5%)
(with an AFR of about 11.0)

-Max

 

ok i see what your saying now, i was thinking 5% of the injectors duty cycle.

i have a haltech though so everything is bar graphs for me anyways :P

 

I use the PFC and this works very well, but this also applies to any ECU for fuel adjustment where you adjust total fuel flow.

 

You have a lot more patience than I do!

 

can you guys point me in to the right direction of learning how to tune, i tried to look it up but it gave me all the wrong info, i want to be able to understand what your talkin about like duty cycle and injector pulse, so please can you help, i love to work on my own 7

 

If you have a PFC, go to that forum and see sticky.

 

I find that it helps a lot to imagine that you are the ECU. You only have a handful of inputs and you've got to deliver the right amount of fuel and get the spark timing right. Or your owner will likely pull you out and beat and/or burn you before replacing you wil a fancy new box.

-Max

 

Just remember how easy it is to blow up a rotary before you begin tuning. If you do a search there is a lot of info on timing. If you are juststarting out, start with the fuel being very rich, log a run, make adjustments and repeat.
John

 

Rotary engine isn't the best platform to learn on how to tune. Make sure to do small increment changes at a time. don't try to adjust everything at once or else you can run into problem on what you changed previously. Everytime after you made a change (that's improved), save that map so that in case when you screw up, you still have the map in hand without having to start all over again. Kinda like writing a paper in word program, always save your latest update. Another suggestion is try not to rush your changes, make sure they're right and repeatable. I know of several rotary guys who started tuning their car (self learning) and could take up to 3-4 weeks adjusting the map and anywhere from 10-20 tanks of gas. At least by the time you have tune your car, you'll know alot about the software.

 

a good thing for you might be to get in on dyno days. lots of guys are complete ******** and don't want you to see what they're doing, but every now and then, you can find someone who will learn ya the ropes.

see if there are any dyno shops in your local area--even if they're not doing rotaries that day, see if they'll let you come hang out and learn something. that should get you a basic idea anyway. if you do it that way, just remember rotaries like to run richer than piston engines.

 

www.efi101.com if you want to learn the right way. It is worth every penny and then some.