Tuning question....

[xtremekustomz]

Ok I got my car tuned with the 2.9 whipple and budget return. Now my question is when i was driving the car and give it some gas so i start building boost (around 7-9lbs) the wideband says 14.5 -15.5 and then once i make over 10lbs it starts to drop to 12 -11.5 and then at 17lbs its good at 11.0 - 11.9 etc..(alittle hard to read while driving) Should it not start to richin once you get into boost cause I can hold it around 10lbs and it stays around 14.7??? Im alittle confused or is my autometer a/f gauge no good or is it a bad tune??

 

[Mystic03]

So you holding at 10psi..part throttle its at 14.0?

 

[xtremekustomz]

Ya does that make sense?

 

[xtremekustomz]

Could it be the maf (SCT 3000) and JLT high boost?

 

[Ontariomystic]

I'd say tune related. At part throttle it will most likely be tuned for a leaner A/F ratio then WOT but that sounds possibly to lean.

 

[Cobra03SC]

The tuner can add fuel down lower for you. It sounds pretty normal though, the fuel dumps in once you go WOT. If you are only part throttle its not going to be dumping fuel. Now i bet if you stood on the gas it would probably drop to 11s right off the bat.

 

[Mystic03]

The tuner can add fuel down lower for you. It sounds pretty normal though, the fuel dumps in once you go WOT. If you are only part throttle its not going to be dumping fuel. Now i bet if you stood on the gas it would probably drop to 11s right off the bat.

+1 just didnt understand your first post

 

[xtremekustomz]

Im just trying to understand the principles in tuning because to me it would seem you would want more fuel as soon as you start building boost pressure or out of vacuum.

 

[Cobra03SC]

Im just trying to understand the principles in tuning because to me it would seem you would want more fuel as soon as you start building boost pressure or out of vacuum.

Thing is you shouldnt be seeing boost while just cuising. Should be at 0 untill you give it a good bit of gas. Its getting fuel where it needs it, like you said it drops at WOT. Im not sure why you would need to be "building" boost since with the roots/twin screws the boost is instant. Now if you were brake boosting a turbo it would be different. If its not sputtering or acting funny while you normally drive, sits at around 15 at idle/cruising and it drops into the 11s at WOT you should be fine.

 

[xtremekustomz]

Thing is you shouldnt be seeing boost while just cuising. Should be at 0 untill you give it a good bit of gas. Its getting fuel where it needs it, like you said it drops at WOT. Im not sure why you would need to be "building" boost since with the roots/twin screws the boost is instant. Now if you were brake boosting a turbo it would be different. If its not sputtering or acting funny while you normally drive, sits at around 15 at idle/cruising and it drops into the 11s at WOT you should be fine.

You build boost as you accelerate up a hill of what have you once the boost gauge goes over 0. My question was why does it read close to 10lbs before any fuel is added on the wideband and seems to run lean till you give it more pedal. Should it not start leaning towards rich as soon as boost pressure is starting to climb?? Im trying to understand the tuning side of this.

 

[svtshadow]

Remember boost is just a measure of restriction.

 

[ScreamingFast]

Yeah you have to drop the hammer right off the bat and it will see to 11's (should depend on what you tuner commanded a/f at). If you go part throttle or less and the A/F will be all over the place. At regular cruising (one speed in 5th or 6th) you should see mid 14 to low 15's fluxing in that range.