I bought a 5lbs (8 3/4") pulley and I was wondering if I need a chip to run it right now? Here is my dyno. Factory truck.

 

For maximum power and safety, Yes.

Your going to need a belt also. Don't get in a rush. Do it right

 

It came with a 68" gates belt (1745mm). I ment to say is it ok to run it for a day or two until I get a chip in and get it back on the dyno?

 

As long as you don't get into the boost you should be OK for a day, it's for you not to be tempted to get on it, if you do you are asking for trouble and BIG headaches.

 

Your A/F of 12.5 and down to 12 at full throttle is perfect. Why would you botter with a chip. You won't get better than that. The computer is already compensating for your pulley.

TB

 

Thats not with the pulley. That just the truck stock.

 

What year is your truck?

 

The computer will conpensate up to 20% to richen the fuel if needed. There is allot of compensation built into the computer unlike what many lead others to believe. O f course the computer has it's limits.

TB

 

anything over 33% sends a SES light

 

It's an 01'. Im thinking about having JDM do a chip. Has anyone had problems with them?

 

Someone please explain this to me.

Less than WOT, and the computer is reading the O2 sensors and adjusting the injector pulses to maintain 14:1 for economy. I see the adjusting there.

But go into WOT, and the computer ignores the O2 sensors and looks to the tables ("the tune"). How exactly does the PCM "compensate" at WOT? Does it overlay some value on top of the fuel tables? If it is ignoring the O2 sensors at WOT, how does it even know that the A/F needs to be corrected?

 

just a hunch but it just measures the air. . .

ok yeah obvious, but you would be flowing more air with the other pulley as opposed to stock, which would be read and conspensated for to a certain degree.

I dunno if thats true entirely or not, or even safe. Just saying that seems plausible.

/not endorsing no chip, tune that thing.

 

I have a Wideband Commander, my 01 was lean with anything other than stock (and then it was not much below 12.5). I have since got an 04, it is a different story. I currently have a 3lb pulley on just for fun, the A/F pulled back down to 12/1 like it was stock after a few times on the throttle. I am just lucky I never blew up my 01.

 

So the theory would be that the mass air reads more air coming in and adjusts some global parameter to avoid leaning out?

 

All I can tell you for sure is the 04 runs richer to begin with 12/1 vs 12.5/1 in the 01, and the 3lb pulley that I thought would make it go leaner in the 04 did not do that. The 04 also shuts off the fuel when you are coasting and helps slow down, my 01 did not do that. Having a wideband was quite an education.