Rebelord

iTrader: (2)

Well, I have 46k on the clock so I decided to change my plugs. They were the factory Denso Iriduim pieces. While I was in there I noticed I had some burns/chaffing on 3 of my plug wires. So I got some Autozone Bosch factory replacement and NGK TR55. I gapped the plugs to .50 as most people recommend here. Well, I USED to be able to get 240+ a tank in city. Now I am BARELY getting 200miles to the tank.

WTF? Whats going on? I dont have any codes. I drive pretty conservative. My mods are in my sig. I've had all these mods for quite some time now. Anybody have any input? Thinking about going back to the Denso factorys. Hell, I might even put my old wires back on.

Thanks.

Very frustrated Ski

Grimes

iTrader: (3)

Dunno...I have the same plugs in my car, and I kept the same gas mileage. Are your wires on correctly?

LS1_Unleashed

iTrader: (12)

I changed to NGK's and noticed a drop in gas mileage also. My gas mileage has always sucked though, but I cant complain. I love my car. But if you find out the plugs are causing it, let me know and i might have to switch mine back.

777

iTrader: (21)

I know you will say you there is no way I didn't put the plug wires on right, BUT TONS of people get them wrong. Go and check to make sure none are loose. There will be two clicks on the coil packs.

Frosty

iTrader: (17)

My mileage dropped too but I added headers and ditched the EGR and AIR.

I thought mileage was suppose to go up after headers and a tune, oh well.

RPM WS6

iTrader: (3)

Never seen a drop in mileage going from stock plugs to TR55s on any of my LS1s....

TAQuickness

iTrader: (28)

as 777 noted. Make sure you have your plug wires on correctly.

Frosty - if you keep your foot out of it you will get better mileage

Rebelord

iTrader: (2)

I'll double check the plug wires. But pretty sure there on correctly. I remember distinctavly listening for the 2 clicks. I'll check it tonight.

Ski

Rebelord

iTrader: (2)

Well, its not the wires. checked those. one thing i have noticed is my "tick" has become louder. Leaning more and more towards collapsed lifter. Heres my dilema. I have to move at the end of this month. I can limp the car around till then. Then I will be dropping the engine out from the bottom to tear it down. Probally take off the k-member and put the k-member back on to roll the car around. Maybe I have a lifter so collapsed that. its just messing everything up.

Ski

Rebelord

iTrader: (2)

TTT please. i kinda need some help on this. I dont want to have something like this when I'll be purchasing HPTuners.

Ski

Cop Car

iTrader: (14)

sounds like they are gapped wrong, Denso Irridium plugs are good for more than 100,000.... put them back in..

Rebelord

iTrader: (2)

That could be a possibility. I will pull them out after I get the car back from the body shop next week. I will check the gap, and if anything put them down to .45

Thanks.

Ski

BigE

iTrader: (2)

You'd probably get better gas mileage opening them up to the stock gap, .060.

shouldaboughttheZ

iTrader: (8)

I run the TR55's and gapped them to .055. I have no problems.

Bill's 02 Z-28 SS

Hi Ski,
When you pull the plugs check the color of each plug, they should be a little brown - if you find one that is darker or a different color that will be the problem wire/plug issue. The LS1 is not the easiest engine to work and some people have cracked the plug(s) installing them or you could have a bad wire. Check the resistant of each wire - the after market wires are about 40 ohm, don't know what the factory wire is. Again if one is out of range that could be the problem. Bad in this case is a high resistant.
Thanks
Bill

Rebelord

iTrader: (2)

I'll check the gap. Dont know whats up. Really starting to **** me off. I'll check the gap and I'll post pics of the plugs. Thanks.

Ski

The PAT WS6

iTrader: (14)

how could a sparkplug/wire problem effect your gas mileage?

Rebelord

iTrader: (2)

That is the only variable that has changed. Right after that my gasmileage went to crap. So, you tell me. Like if you have 4 matching tires and your car drives straight. Then you change to 4 different tires and your car drives all crazy. Must be the tires. Thats why. I consider myself pretty mechanically capable of almost anything. I'm not an idiot. I only posted this incase someone esle had a similar experiance and found out what it was. Maybe then they could provide me with some insight. Thanks everyone for there input. I'll just have to deal with it for a few more weeks. Then I'm dropping the engine out and tearing it down. Thanks.

Ski

Schantin

iTrader: (6)

I have TR55's. No problems with mileage from that (can't say the same for other parts on the car.....) Anyhow, check the resistence in the wires and that they're connected properly (as mentioned before) Also check and be sure a spark plug didn't loosen up and is backng out of the head. The torque on then is only like 12lbs. Double check the gap too.

I know it's frustrating....but the NGK plugs won't decrease your gas mileage... unless one is damaged. Didn't by chance drop ne during install, did you? That could create a prob if the ceramic has even a hairline crack.......

Good luck and hope this helps......

gwj

I would not gap the TR55's @ .045. I believe NGK advises a gap change of no more than .010 from the off-the-shelf gap (they usually come gapped @ .059). I've run .055 - to .059 with absolutely no problems or change in gas mileage. I've done 5 plug changes in 130K miles, all NGK TR55's.