They are set in stone. That is what the tuners are changing (in terms of the major changes)when they burn your chip (along with other things). A chip in a nutshell increases timing on the low end and and maybe even across the board and may lean out or richen the WOT fuel tables based on your application. For instance with stock boost, the chip will be tuned to lean out the WOT fuel in an effort to gain HP but still stay safe.

 

So by adding a pulley, you are gaining boost AND leaning your WOT mixture. I am assuming the A/F stays the same as stock when not at WOT, which means more fuel consumption.

Well after all this discussion (and useful I might add) maybe someone will chime in with the answer to the original question!

 

I am pretty sure that in closed loop mode when you are just cruising, even with a burn on the chip, the computer leans out the mixture just like the stocker. When I took A/F ratio at the dyno before I hit it (with a 4# lower and 1# upper), the A/F was at like 15. This is one way that chipped and pullied trucks can pass emissions.

I'd be curious to see an answer to the original question too...

 

Idle:
both a chipped and a stock will sue the sensors to get 14.7 A/F

Partial throttle (closed loop):
chip and stock will run their own timing and adjust from their base fuel tables. Note there is a maximum the computer can add due to the O2 sensor. For example, a 10lb pulley with no chip WILL run lean (gross example)

WOT (open loop):
chip and stock ignore sensors and dump gas strictly based on MAF reading. Tables are optimized for an expected MAF reading per RPM range. Outside of that, the computer will extrapolate (sometimes correctly, sometimes not)

It's amazing what the stock chip can compensate for. It's also amazing how much better the computer runs when a chip is installed and it has the correct base tables to base corrections on.

Coldie

 

Good info Coldie, thanks.

Where did you get your info?

 

Ive seen a 2002 on a wideband equipped dyno peg a 13.7 a/f with just a Filter, 4# pulley and Exhaust. Please dont tell the people here its ok to run such mods without a chip unless you plan on paying for their engine. Each and every truck is different. The Ford computer uses a pre-set table for fuel and timing as no way in hell can compensate for the added boost and needed fuel.

13.7 was @ 5400 rpm... Is this safe? Hell no!

What will the chip do? Thats up to you.. Dont do a mail order chip first of all and secondly, get on the damn dyno and get a real tune. Your tuner should KNOW when to add fuel ( most likely ) up on the top end.. Should lean you out on the bottom end most of the time. Stay away from insane street timing such as 18-21 degrees of timing.

Use common sense.

 

What people do with their own trucks is up to them. I am just trying to learn (and help other people learn) how our trucks respond to mods instead of just jumping on the bandwagon with lots of other people by believing everything I read, i.e. if you run a pulley you MUST run a chip.

Also I thought the rev limiter kicked in before 5400 RPM on an unchipped truck???

 

Right on!

 

My mail order chip ran fine.......had it dynoed many times and timing tables read also.

16* street
20* race

--Joe

 

You would be surprised how many L owners DONT dyno their mail orders...

 

I guess you are talking about me. I will be doing some testing and tuning on my own in the near future.

 

So what's with the JLP Delta Diablo chip in your sig? Or are you flashing the stocker?

 

I use the Delta chip at the track (with race fuel) and the stock program on the street. I believe this will give my trans a little more life and my A/Fs and timing are not as aggressive.

I am changing over to 55# injectors so I may need to use a chip as it may make me run too rich. I will be doing some tuning on my own to see if I can tweak this baby the way I like it.

 

Maybe he used to run it and removed it

--Joe

 

But those table values that are used for fuel delivery are based on maf readings. Increases in boost increase airflow and therefore increase maf readings. The computer will respond with more fuel based on more airflow. From what I understand, in open loop (wot), three components go into the calculation: load, MAF readings, and MAP sensor data. In closed loop, 02 sensors are used, of course.

These are not fixed numbers and as they change, the computer will react accordingly. The ultimate question is how far above the peak values a stock engine will produce are the tables filled in for?