A98Z28P

I'm new to this so please don't lash out at me for asking.

I bought a 98 z28 m6. 136k miles. It has a "bigger camshaft"(the idle is REALLY choppy) cruising rpm is 2k-2.5k, dual exhaust, bullet mufflers, and an MTI lid... Right now I'm getting really shitty gas mileage. like 8-12.
I just joined the navy and have a need to drive 4 hours at a time. Long trips.
Could someone give me some pointers on a less aggressive camshaft. Or how I might achieve better than stock MPG?

Jon@Texas-Speed

iTrader: (18)

Even with a HUGE cam it should be getting better mileage than that. Is it throwing any SES lights? You might make sure the O2 sensors are good and clean the MAF sensor. Those are two of the first places that normally cause the symptoms you are seeing. Do you have any idea on how big the cam is that is currently in the car? That will give you an idea on where to go from here if you want to change the cam out.

Jon

lt1pwr1

iTrader: (1)

Not sure about your mechanical knowledge but does it seem to run/idle good or does it die or stumble? Just wondering if the car has been tuned? I would think so but you never know....people spend hundreds or thousands on mechanical components and then cheap out by seeing if they can get away without tuning it or they will do a mail order tune only. Kinda reminds me of the people my dad talks about that come into his work. They will drive a $60K Denali but the gas tank is always on E when they come in and he needs to take it for a test drive

And yes, typically people see bad o2's on these cars which cause bad gas mileage. These LS1's are pretty particular as well so don't go with an aftermarket Bosch o2 if you change them out. Go with AC/Delco/Denso.

A98Z28P

Thanks for the replies.

@Jon - It is throwing SES lights. I don't remember exactly what the reading was but it was something with the EGR. I thought it was doing it because the exhaust ends right under the driver/passenger seat. And I have no idea how big the cam is. I know its bigger than stock. I failed to get a list of mods when I bought the car. Any way I can find out what cam is in it?

@lt1pwr1 - The idle seems to stumble sometimes. Like its about to stall then doesn't. I don't think the car has been tuned.


I was talking to man at Oreillys and he was telling me that chances are if im running true dual exhaust then I probably have long tubes. And with the cam that big in it I wouldn't be able to drive for four hours at a time without the car over heating. I don't think thats true. But then again I'm not very mechanically inclined.

zracer323

iTrader: (12)

No thats not true...I wouldn't take any real car advice from people at those stores.

I would do the simple tune up items like O2's, clean the MAF, change plugs, etc. If this stuff doesn't work, then take it to a reputable tuner and have him look at the tune. Odds are a good tune will make a huge difference on gas mileage

TransAm Bandit

Change Your 02 Sensors.
Plugs.
right tune.
Fuel Filter.
Check ur Air Filter.
Clean Ur MAF.(Becarful they Can get Damage Easily) better to Use WD40
And Try to Go With MILD cam Which will give you smoth IDLE.
Get Rid Of That SES Light

A98Z28P

What cam do you suggest? I was looking at the Gm Hot Cam.

garygnu

a EPS 222/226 cam,or tr224 .or compcam 54-408-11,54-455-11.

TransAm Bandit

There Are Many Expert Guys Here To Give U Right Cam Choice.
COMP Cams-CCA-54-408-11 Can Be good One for You

Jon@Texas-Speed

iTrader: (18)

If the car is open headers, that is your mileage problem. The O2 sensors are getting air pulled back across them and adding a bunch of fuel. Put the rest of the exhaust on or some extensions off the headers and you should be good to go.

Jon