Gas Mileage

[ledzeppac]

I am a new GN owner and I am gettign terrible gas mileage. It is relatively stock. Upgraded fuel pump and exhaust and thats about it. 64,000miles. Regualr oil changes. I am getting 16 miles per gallon!!! I am not flooring everywhere but do "get on it"
What is everyones else getting gas mileage wise. Any suggestions.

 

[MistaScott]

16 isn't bad overall. Most get between 15-22.

I think I average 22 highway, 15 city.

If you are into boost a lot, your fuel won't last nearly as long as it would otherwise.

 

[Turbo6inKY]

Second on the 16. You're on the lower end of "normal."

Its normal to get 16-18 around town. EPA mileage for the car was 17 city.

Check the mileage on the highway. Get a good fifty miles on it with the cruise control set at 65. If its not above 22, you might have a problem. On a fairly stock car, you should see 24-26mpg @65mph on level ground.

 

[OneLethal87GN]

Has anybody tried a chip with the "lean cruise" feature? I don't know alot about it but I was planning on getting it burned into my new chip. I think your air fuel ratio goes to 16:1 after resuming the same speed for a certain period of time. This is what gives the better gas mileage. If anyone has this feature please chime in with your results.

 

[ledzeppac]

Ok, on a green light I ussually DONT go under boost at all. Do you? How do you guys take off from the line, under normal driving conditions.

 

[MistaScott]

I usually spin tires...

Just kidding... I am at about 0 vacuum but the turbo usually doesn't build any boost when I get off the light. The factory specs were 17 city, 25 highway. But the consensus is that the 25 is overstated. The GNX specs were slightly lower mpg.

There are a million causes of poor gas mileage, I'd get some scanmaster numbers as a start. Also make sure you are filling up with 18 gallons. Due to the vapor auto shutoff I usually only get 15 or so. That can screw up the numbers.

 

[scottyb]

100% city here, and I NEVER see better than 15-16.

Regarding acceleration, I also usually try for just under 0 vac. This is the sweet spot where the turbo whistles, music to my ears. Unfortunately, traffic usually prohibts this rate.

 

[Dan Thompson]

If you have a Scan Tool check your BLMs on the highway at a steady speed.

My BLMs are 135 at 65mph, which is just a little rich, and I can get almost 20 when the wife is with me.

A reading of 128 BLMs is just in the middle, not rich, not lean. The higher the BLMs above 128 is getting richer.

 

[MistaScott]

Originally posted by Dan Thompson
If you have a Scan Tool check your BLMs on the highway at a steady speed.

My BLMs are 135 at 65mph, which is just a little rich, and I can get almost 20 when the wife is with me.

A reading of 128 BLMs is just in the middle, not rich, not lean. The higher the BLMs above 128 is getting richer.

Actually, other way around:

>128 is lean

<128 is rich

 

[ledzeppac]

Thanks for all the help. I actually have another problem to worry about now. I was side swipped yesterday by someone on the way to work. Anyone know of a good body shop/paint guy in Orange County ,CA?

 

[JP87GN]

Originally posted by MistaScott
Actually, other way around:

>128 is lean

<128 is rich

Thats what I was going to say! while we're on the blm subjet, I installed a powerplate the other day and went for a cruise, my blm's were just below 110 at a freeway cruise, but when I floor it the blm's jump right to 128 until I let of the gas. what can I start tuning to get my blm's closer?

 

[Roc87]

Used to get around 18MPG, but all I can get now is around 15. Still gets over 22MPG on the freeway. Not bad for 50# injectors!

 

[ledzeppac]

Yeah, I believe I should be getting around 18-19 for the way ive been driving and half is on teh freeway. But like I said, someone just hit me and now I need to get it fixed!!!!!!!!!!!!

 

[JP87GN]

I'm a autobody tech. ,to bad your not closer I could have helped you out.

 

[MistaScott]

Originally posted by JP87GN
Thats what I was going to say! while we're on the blm subjet, I installed a powerplate the other day and went for a cruise, my blm's were just below 110 at a freeway cruise, but when I floor it the blm's jump right to 128 until I let of the gas. what can I start tuning to get my blm's closer?

What were your BLMs before the power plate?

As long as it isn't pegged in either direction (105 or 150) you have nothing to worry about. Maybe lower static fuel pressure a psi or so. Also, if you run a translator you can adjust idle lean/rich settings.

I get about 115-124 at cruise, 122-127 at idle.

 

[NEARING]

17 mpg on a 300+ mile road trip at 65-75 mph, playing a little bit

I have a non-lockup converter so with a L/U unit I may have seen 19-20, maybe.

 

[CTX-SLPR]

Howdy,

While I don't have a GN I know that a L/U converter will make a bigger difference than 2 mpg on the freeway. With my 468 big block Riviera I drove from Raton, NM to Lubbock, TX on a single 20 gallon tank with the converter locked driving hard at 80-90 mph. After leaving Lubbock on a new tank I forgot to lock the converter and burned half a tank getting to Midland, TX cruising at about 65mph! Thats about 17 mpg for the first leg and only about 12 mpg on the second! It also raised the operating temperature from 185 to about 215. Having a L/U for crosscountry is key.

Just my .01, my advice ain't worth anymore than that,

 

[QuickWrench]

Check my signature.

My GN [with the identical buildup] got 27.4 MPG driving from Cleveland to Bowling Green, KY (490 miles). This was with an Armstrong 93 chip, cruise was set at 72 MPH (~2200RPM), boost lowered to 16PSI, Fuel set @ 38PSI.

Slicks and tools in the trunk.

 

[Dan Thompson]

There is a shop down in Lake Forest by Lou's old garage. I had them give me an estimate on a new paint job, $4,000, a little high for me so I didn't get it done.

I didn't get a business card and they are not in the phone book.

 

[ijames]

The original poster is in California, which gets RFGII gasoline (unless they've come out with RFGIII), which means that his mileage will be down about 25-30% from the original EPA mileage stickers. We get it here in MD as well, and around town with lots of short trips/cold starts I get 14-15, and on the highway about 19. On a long trip where after the first tank I'm buying "real" gasoline down south the highway mileage goes up to 22-24 mpg so it's not the car. Nearing, I'm not sure what gas is in your area - western, southern VA gets good gas but you might be too close to DC.