ahritchie

iTrader: (1)

Hi everyone, I recently started to daily drive my 94 Formula 6spd after rebuilding the motor and doing a cam swap at the same time (this car sat for over 2 years wrecked); before it got about 19 MPG with 50/50 highway/city driving. Now, its averaging 150 miles per tank which is about 10-11 MPG....needless to say with gas prices the way they are it is getting expensive real quick to fill up every 3 days. I know f-bodys are not meant to be gas savers but this is ridiculous....I also have a 99 Firehawk and consistently get 19-20 mpg in that car with the same driving style, so I'm not driving like a bat out of hell all the time. The cam I chose is not that big so it should not cause that big of a drop in mileage...I'm running a Lunati Voodoo 60121 (219/227 515"/.530"), 1.6 RR, beehive valvesprings, 52mm TB, CAI, mid-tube headers, no cat, magnaflow exhaust, and a PCM for less mail order tune. Also the mass airflow sensor and coolant temp sensor (on the water pump)were replaced recently. My buddy who helped me with the motor says the valves might need to be re-adjusted...could that cause this bad of mileage? Also I noticed last night when I filled up the tank I kept getting a strong gas smell in the car while driving...I got home and looked up under the car and could smell gas but it's not leaking or anything....ideas anyone? I'm taking it to a local shop next week for a dyno tune....maybe that might help but I want to make absolutely sure all mechanical/sensor issues are fixed before I get it tuned. HELP!

lncboytre_d

if the smell of gas is that strong the tuner probably won't let you on the dyno. Check for leaks at the injectors and check your spark plugs. Your car sat for two years, could also be a weak ignition system. Just my .02¢

BlackBird87

iTrader: (6)

Im having the exact same problem with basically the same car/setup. Im pretty sure its the tune, being that its mail order they dont want to motor leaning out and going boom so just dump fuel. Im gonna pick up a windband kit soon and have the tuner use that to tune it

95 mystic ls

iTrader: (12)

Tune. Have two buddies that have decent size cams with M6 and get over 30 MPG on the interstate and high 20's in town.

VinR1

iTrader: (17)

LT1's?? my bone-stock auto doesnt come close to that

WS Sick

All the cam heads cars I have had got horrible around town but low 20s at cruising speed on the highway. But I'll bet the tune is a little fat.

95 mystic ls

iTrader: (12)

Mine didn't get but 12 with an auto.They both had M6,one with 4.10, the other 3.73 gear. Yes they are LT1's

nitrous2fast

iTrader: (2)

Most of the time after a cam install the mileage drops because of the orientation of the foot on the pedal. This has been verified by many professionals in this field.

LSWHO

iTrader: (1)

Is the new MAF a stock maf?

ahritchie

iTrader: (1)

Yes, it's a stock replacement MAF from autozone; still has the screen and everything....also I have not been driving it THAT hard to get 10 MPG...just put in a new clutch and have been taking it easy the last 2 tank fulls to break it in by driving "normal" most of the time. The worst it ever got before the cam/mail order tune was about 200 miles to a tank. And did I mention it smells rich as hell? I guess most of the smell is due to no cat. Also, the spark plugs, wires, ignition coil, ignition control module,cap and rotor were replaced during the rebuild. I'm gonna have my buddy re-check the valve adjustments and hopefully the dyno tuner can fix whatever is wrong with the tune if that is the case.

Anybody from the Charlotte area familiar with Sigma Six Dyno Services in Concord? I was referred to get a dyno tune from here since there are very few LT1 dyno tuners around anymore....it's all LS tuners now. Hopefully they know what they are doing because it runs $400 for 3-4 hours on the dyno.

1961ba427

iTrader: (26)

Have you checked your fuel pressure? Taken off the vac hose to make sure it wasn't full of gas? It could be a coincidence that this started with the cam swap.

LSWHO

iTrader: (1)

Are vatozone mafs worth a damn??

Also what about an exhaust leak?

nascarnate326

iTrader: (1)

right foot mod?

sdm1234

iTrader: (8)

When I did my Lunati 60121 cam swap, my PCMforless mail-order tune was way off during part-throttle. There was bucking, floating idle issues, and decceleration pops before I had someone local tune it out nice and smooth. I can see that being an issue for MPGs. Their WOT tune never missed a beat though for anyone who's wondering.

wrd1972

iTrader: (12)

Mostly tune. The gas smell could be a busted EVAP system assuming you stil have it.

tbird31

iTrader: (22)

Not that you're a liar, but there isn't any way in hell that ****'s happening... I could see high teens around town if you BABIED it and low to mid 2x's on highway, but high 20's in town and over 30 on highway... not happening...

FWIW, I have a big H/C car and I get 13-15 city (less if I'm in it) and usually high teens low 20s on the interstate.

myltwon

iTrader: (1)

if I could find a LT1 that got that kinda mpg I'd pick it up for a beater.

wrd1972

iTrader: (12)

indyboom

iTrader: (11)

I get 28 on highway with 3:23's and m6.. turd

00FlowCamaro

You have 3.23's in your M6? I thought they all came with 3.42's. You get 28 not over 30. I do find it hard as hell to get 20's in town driving a V8, period.