Putting two intake air sensors in series to increase stock fuelin..

[fredw]

Trying to get bb turbo dialled in and having some issue with mid range lean pops.. It seams even with fuel controller maxed out I'm still getting very lean a/f numbers on wot and 6000 feet

Choices would be to go to a bigger secondary injector or find a way to get more fuel threw stock injectors ..

Was told that by putting a extra air intake sensor in series it doubles the resistance the stock computer sees, thus thinking its 10 degrees colder than it is and adds 5 percent more fuel across entire fuel curve threw the stock injectors

Has any one done this on a turbo application and found it to work well??

 

[Bacon]

Can you get a rising rate regulator for a Doo.

 

[worx53]

I would think it would require more than a 10 degree spread to start adding fuel( more like 20 0r 25) but I have not seen an accurate chart listing those parameters. I have the data for the ohms for the older sdi mach and 600 but haven't been able to get that data for the ETEC. If I remember correctlt the sdi had a base fuel at like -40F and then subtracted 3.5 to 5% in increments up to 50F I think it was.....

 

[fredw]

My understating was that the etec changes fuel curve every 1 degree c... It reads up to -40c

So if you can have ecm think it's 10 degrees colder that is is 5 percent more fuel added...

Had received info last night that there is 872 bbs that have three of these intake sensors in line adding fuel and it works great

 

[Wheel House Motorsports]

your secondaries should be able to add enough fuel to drown that motor with ease.

Might want to speak with whoever sets them up and get a program that allows for more fuel added. what brand controller is it?

 

[corvette Z]

Trying to get bb turbo dialled in and having some issue with mid range lean pops.. It seams even with fuel controller maxed out I'm still getting very lean a/f numbers on wot and 6000 feet

Choices would be to go to a bigger secondary injector or find a way to get more fuel threw stock injectors ..

Was told that by putting a extra air intake sensor in series it doubles the resistance the stock computer sees, thus thinking its 10 degrees colder than it is and adds 5 percent more fuel across entire fuel curve threw the stock injectors

Has any one done this on a turbo application and found it to work well??

I started using 2 iat sensors in 2012 on my first 872 as I wanted to add a little fuel consistently throughout in all conditions.
For giggles, also tried on my Boondocker turbo and it caused poor low rpm response.
If your controller is maxed and you're lean - likely injector is too small or fuel pressure is falling.

 

[fredw]

Talked with Chris at dobec, it's the gen 3.5 version controller and he tells me that with this tune loaded there still is fifty percent more fuel that the stock secondary injectors can handle

He will make up a new tune and we can download it for this bb... To be running the amount offuel I am with this new build, he says its pushing lot of air over stock setup...

The idea of adding air intake sensors can also work fine and could also help... Might have to try them both to see what works better

 

[corvette Z]

Talked with Chris at dobec, it's the gen 3.5 version controller and he tells me that with this tune loaded there still is fifty percent more fuel that the stock secondary injectors can handle

He will make up a new tune and we can download it for this bb... To be running the amount offuel I am with this new build, he says its pushing lot of air over stock setup...

The idea of adding air intake sensors can also work fine and could also help... Might have to try them both to see what works better

With a turbo you are battling low rpm, low airflow, high tps position off idle. Extra fuel there is a problem.

 

[corvette Z]

Talked with Chris at dobec, it's the gen 3.5 version controller and he tells me that with this tune loaded there still is fifty percent more fuel that the stock secondary injectors can handle

He will make up a new tune and we can download it for this bb... To be running the amount offuel I am with this new build, he says its pushing lot of air over stock setup...

You have a locked tune and cannot change in the field?

 

[worx53]

I'd like to know if that's accurate. So then 30 degrees change is 15% more fuel? Can anybody verify if this is accurate?

 

[fredw]

Well put in the extra air inlet sensor in series and will try it out soon.. With stock gen 3.5 fuel controller... Hope it works the midrange lean spot out

 

[inspector01]

That is a VERY rudimentary way of making changes, you would be better off putting a potentiometer on it, it costs less and at least has some adjustability. That being said, I'd only do that as a last resort if no other options are available (remember, any changes you make to fueling by tricking sensors will have unknown impact on other aspects of the map).

 

[corvette Z]

That is a VERY rudimentary way of making changes, you would be better off putting a potentiometer on it, it costs less and at least has some adjustability. That being said, I'd only do that as a last resort if no other options are available (remember, any changes you make to fueling by tricking sensors will have unknown impact on other aspects of the map).

Explain how a potentiometer will work vs a second iat sensor in series. Are you just throwing out there unknown impacts or do you have specific knowledge ?

 

[inspector01]

Explain how a potentiometer will work vs a second iat sensor in series. Are you just throwing out there unknown impacts or do you have specific knowledge ?

A second IAT sensor will change the resistance of the circuit, causing the ECU to read a different IAT. A potentiometer can change the resistance of the circuit as well, but gives you the option of changing that resistance to adjust what the ecu reads.

When you trick sensors to achieve a desired result (in this case, adjust AFR), you also adjust EVERYTHING that is affected by that sensor, most of which you can't see. So although tricking a sensor can allow you to reach a desired AFR, it is throwing off other things that you don't know about, such as timing.

 

[corvette Z]

A second IAT sensor will change the resistance of the circuit, causing the ECU to read a different IAT. A potentiometer can change the resistance of the circuit as well, but gives you the option of changing that resistance to adjust what the ecu reads.

When you trick sensors to achieve a desired result (in this case, adjust AFR), you also adjust EVERYTHING that is affected by that sensor, most of which you can't see. So although tricking a sensor can allow you to reach a desired AFR, it is throwing off other things that you don't know about, such as timing.

What is desireable , using the 2 iat sensors in series method, is that it changes the percent linearly thru all temps. You could use a P.C.5 or similar to add about 4% to the entire fuel map and get the same result. I have P.C.5 but do not use it as there is a lot of logging needed to build a proper map and there are some anomalies with etec afr such as lean cruise.
Timing maps typically don't have much change by iat temp unless it is in the hot area. Tricking water temp, especially with etec can change a lot of things.
A set resistance can be right but only at one area of the map

 

[corvette Z]

I'd like to know if that's accurate. So then 30 degrees change is 15% more fuel? Can anybody verify if this is accurate?

Here are approx. dry air density %'s using -40C as 100%
-20 C 92%, -10 C 89%, 0C 85%, 10C 82%, 20C 79%

 

[corvette Z]

Talked with Chris at dobec, it's the gen 3.5 version controller and he tells me that with this tune loaded there still is fifty percent more fuel that the stock secondary injectors can handle

Gen 3.5 say they can remove fuel. Was not aware that any consumer available controllers could do that with etec. Is this controller capable of that ?

 

[Wheel House Motorsports]

Talked with Chris at dobec, it's the gen 3.5 version controller and he tells me that with this tune loaded there still is fifty percent more fuel that the stock secondary injectors can handle

Gen 3.5 say they can remove fuel. Was not aware that any consumer available controllers could do that with etec. Is this controller capable of that ?

not on etec models, they are just using them to drive the extra injectors in the throttle body boots on the etec.

 

[worx53]

Do you have the Ohms readings for the sensor in relation to the temp and fueling?

 

[worx53]

I was told they wired them in parallel (which would double the ohms reading). Looking at a 800r carbed ats chart this would jump more than one fuel segment unless the etec added fuel every degree as stated above and the 800r carbed ats sensor is ohm testing the same as a 2015 etec I've tested. So does anyone know for a fact that the etec adds fuel for every 1 degree c ?