General Maintenance & Repairs - Really bad gas mileage!

I'm not a new LS1 enthusiast, but I'm not sure where to post this:

My 01 Z28 has about 40k miles. I used to get pretty good gas mileage.
The last time I drove to Vegas I got about 29. This time I got 23. That's a big difference. Also around town I'm lucky to get 19. I haven't changed my driving style at all. This has been going on for a while now.
One thing it might be, but it just happened is I got a SES code. I pulled the code and it's code #P0357. It has to do with the #7 coil. Also I have never changed the stock plugs. Could this make that big of a difference in mileage?
Thanks for the input.:usa:

Heck yeah it could. It's prolly the plug, but possibly the coil pack or the wire.

you need a tune up homey, same shit happen to me, after new plugs, wires and a fuel pump/filter(one of those) it was back too all good

Plug could have folued out. Replace them with NGK-TR55's.

I get 19 around town since new. It might be due
to an itch in your right foot....

I get 19 around town since new. It might be due
to an itch in your right foot....


Ya I get 18-19 most of the time. I think it is due to the same itch.

Adan

I definately do have an itch since I installed that pesky Magnaflow cat back :D but my mileage has been bad since before.

I know alot of people swear by the NGKs but, I have a set of Bosche +4s that I got for free. How good are these. My dad used to use them in his dirt track car when I was a kid. I was thinking of having the dealer change the plugs while I have them check out this SES code/ coil thing. I got a free 100k mile warranty, I might as well use it.:)

19 miles to the gallon..... whats that???? yeah change your plugs and while your in there u might as well change the plug wires too. I dont even get 19 miles to the gallon on the freeway on trips. About 13 in town and 17 on the freeway.

Bosch = good in any thing not domestic.
I wouldnt run bosch plugs if they were free, installed for free and I got paid weekly just to keep them in my car.

When I worked at pep boys we had a special on bosch plugs when we stopped carrying every thing else. Probaly 6 out of 10 customers with domestic cars that I installed them in came back. One actually brought back his regal and watched me pull back out all 6 plugs so I could show him they were new, they charged him R+R plug labor a 2nd time :D

I used to work at Pep Boys. I got the +4s free through a contest. Why don't they work well in domestics. My Dad ran them in his 440 Cuda way back when. How long do the TR55's last? I thought they didn't last very long. Would the dealer carry those. i really don't feel like changing the plugs out right now. i've looked to see how hard they are. It looks like fun.:bomb:

I wish i just had bad plugs. Im only getting 8mpg with no trouble codes. I dont know whats going on. I think i have a major vacuum problem.

I used to work at Pep Boys. I got the +4s free through a contest. Why don't they work well in domestics. My Dad ran them in his 440 Cuda way back when. How long do the TR55's last? I thought they didn't last very long. Would the dealer carry those. i really don't feel like changing the plugs out right now. i've looked to see how hard they are. It looks like fun.:bomb:No kidding... if ya take the coil packs off, it's not near as big a pain..

I dropped off the car at the dealer this morning. I have a 100k warranty but I think they're going to charge me for diognostics even though I gave them the code and told them what was wrong. They also will only replace the plugs with Densos. I asked for just an estimate. He also said that the stock plugs were good for 100k miles.:eyes:

OK now I'm pissed!! There's a short in the wireing to the #7 coil from the firewall. You have to take the fuel rail off to get to it. The thing that pisses me off is that my warranty doesn't cover it. If that isn't the biggest crock of shit! $200.00 to fix, no parts just labor and $78 to diagnos. I'll just do it my self thankyou. I'll have my dad help since he's a master tech. What the hell did I get this stupid warranty for! It's useless. I'm thinking of telling them to shove the warranty where it counts and they can replace the #1 piston instead since that's all they said they would do. This f'n sucks!!!!

Why doesnt warrenty cover it?

Because warrantys are just like car insurance.

They make their money by not paying when at all possible.

I realize that but what are their grounds for not covering.

Mine can barely get 21 on the freeway in 6th gear cruising at 70! It's always been like this. Just changed the plugs and wires about 2000 miles ago. I can barely get 240 out of a tank. I thought these stories about 25 MPG were myths at first. Maybe I'm just checking it wrong.

Ryan

....changed the fuel filter not long ago too.

Ryan

Supposedly I have the basic warranty which only covers major parts of the drivetrane (sp?), like internal stuff. So the short in the wiring doesn't count. Also I believe it's state law that if your car is under 50k miles anything that affects emissions is covered underwarranty. The service writer told me it wasn't a component failure it's not covered which is total BS. If I'm getting a miss fire I'm not gonna pass emissions, so it's emissions related. So anyways, I told him I was going to make a call when I was leaving his desk. and when I was getting my car after paying $78 for diagnostics when I already knew what was wrong, he came up and told me he would talk to his service manager. If I had know this was going to be such a big hassel for them I would have fixed it myself and saved myself the $78. Or maybe I should just go trade in on a Cobra or something. GM sucks! I'm going to let them know this too. I used to be a chevy guy. My first car was a Camaro, but I may be going to the dark side. Sorry for the rant.

Or maybe I should just go trade in on a Cobra or something. GM sucks! I'm going to let them know this too. I used to be a chevy guy. My first car was a Camaro, but I may be going to the dark side. Sorry for the rant.

I can understand why you'd be thinking this with the crap they gave you. Before you consider that, I'd find out if ford would be any better under similar circumstances. Just a thought. Maybe you've already thought of it.

i use ngk iridium plugs they cost me bout $56 for the set and so far no problems so i would def recommend them to any1.

I can understand why you'd be thinking this with the crap they gave you. Before you consider that, I'd find out if ford would be any better under similar circumstances. Just a thought. Maybe you've already thought of it.
dude this thread is about three years old. I'm pretty sure the problem has been solved by now.

dude this thread is about three years old. I'm pretty sure the problem has been solved by now.
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