Vec 2/3 guys

[99 R/T 10]

For those that tune themselves. I am trying to get a little better mileage out of the car. Right now I am at 16-17 MPG while cruising. I normally sit between 0 to 10 inches of vacuum while cruising at 70-80. How lean can I go on the program? Can I take it negative while not in boost? And will it affect the boost side at all?

TIA...........

 

[plumcrazy]

didja ask dell ?

 

[99 R/T 10]

Hey Phil!!! I did, but don't want to bug the boy too much. I just wanted to see where others have set theirs and compare that as to where I'm at.

 

[KNG SNKE]

I am interested in this as well. My car since day one, pre Roe has gotten 17.5 mpg. My previous Viper, same year, more mileage would get 21 to 23mpg highway. Now that the Roe is installed I still sit at 17.5 mpg.

 

[plumcrazy]

thats on the highway at normal cruising speeds ?

i never get less than 21 and as high as 24mpg

 

[99 R/T 10]

With the Vec as a piggyback, it is adding fuel depending on the programed table at a certain amount of boost. Most just tune from 0 boost to WOT, and not worry too much about mileage.

 

[KNG SNKE]

Yes, on highway cruising speeds for me. Can't figure out why this Viper is so different from my last, even before the supercharger. New plugs, new wires, etc.

 

[Red Snake]

You guys drive like women. I get 10-12 cause I can't keep my foot out of it.

 

[99 R/T 10]

You guys drive like women. I get 10-12 cause I can't keep my foot out of it.

this is funny because I just filled up tonight and got 13................ I was beating on it kind of hard lately. Had to break in the clutch......

 

[KNG SNKE]

I was beating on it kind of hard lately.

Be careful, you might wear it out again.

 

[uvbnbit]

Seems like that would be a question for Sean?
Also, I didn't realize the VEC could be (if it can) tuned that way. I assumed stock PCM controlled fuel/air based upon throttle position and/or boost. especially since more air is constantly being forced into intake (w/Roe SC), therefore needing more fuel?
So, if I understand correctly, you're wanting to have the VEC fool the PCM to think it's under vacuum to pull fuel out??
As long as it's not under boost, what air/fuel ratio would you shoot for, for mpg's? 17,18:1? more?
(sorry if this doesn't make sense, I'm on Loratab from hernia surgery friday)

 

[99 R/T 10]

Seems like that would be a question for Sean?
Also, I didn't realize the VEC could be (if it can) tuned that way. I assumed stock PCM controlled fuel/air based upon throttle position and/or boost. especially since more air is constantly being forced into intake (w/Roe SC), therefore needing more fuel?
So, if I understand correctly, you're wanting to have the VEC fool the PCM to think it's under vacuum to pull fuel out??
As long as it's not under boost, what air/fuel ratio would you shoot for, for mpg's? 17,18:1? more?
(sorry if this doesn't make sense, I'm on Loratab from hernia surgery friday)

Don't lift any heavy object!!!! Hope you're feeling better Chip!!!

I am wanting to get 15-16 under vacuum, not messing with the tune under boost. Not sure if this is the "driveabilty" aspect of the tume, but better mileage is prefered.

 

[EllowViper]

OEM I got 21 on the highway. With the 2.4 blower I got 17 mpg. With the 2.8 and blower cam I'm at 13 highway. Average at most fillups is 10mpg.

 

[uvbnbit]

Yes, it would be great to have a "Hwy tune", knock down about 25+mpg. If it's possible, would there be any bad long term effects from running lean (low rpm/vacuum)? Surely, someone's tried this already.
If ran too long outside of the factory adaptives, probably throw a CEL ? ? reprogram PCM?
-signed, Loratab

 

[speedracervr4]

Yea my 2.4L blower gets 18mpg on the highway. Cruising at 70-80 my AFR is 16.5-18.1 and it idles pretty much at the same AFR.