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Discussion Starter #1
Im my ETC im getting around 11 MPG city and 18 mpg MAX ont he highway.

whats doing this? I think it may be bad O2 sensors making me run rich.

I average aobut 200 miles on a tank. its not fun when premium is almost $2 a gallon. I have to fill up more than once a week.
 

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2005 CTS-V, 1994 Infiniti Q45
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Jay, THANK GOD IM NOT THE ONLY ONE THAT GETS TERRIBLE GAS MILEAGE!

Anyway, from my professional analysis :D on my Q, these are the things that can cause bad gas mileage
- o2 sensors
- dirty TB
- dirty plenum
- dirty injectors
- dirty intake/air filter
- Im not sure if the 95 has a MAFS, but if thats messed up that could also cause problems.

All of these thing would apply to your car also.

You may try something; its a gas additive called BG44K. I have heard nothing but good things about it on my infiniti boards. I dont think you can get it at any auto stores, but i know for sure you can get it at www.infinitipartsusa.com and search for bg44k. Its $17 for a can, but if you get 5mpg better its worth it. If that doesnt do anything, your going to have to goto a dealer and have them completely clean it out. Im sure that will help.
 

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1984 Fleetwood Brougham coupe
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it could also be a bad batch of Rice Wes :D
 

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2005 CTS-V, 1994 Infiniti Q45
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Another possibility!
 

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Discussion Starter #5
maybe it has to do with my surging problem. when im crusing in town with my foot ont he gas just enough to keep speed the car surges like the TB is opening and closing constantly... I think the IAC valve might be acting up.
 

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Jay, is you FPR (Fuel Pressure Regulator) good? If you disconnect the vacuum line to it, look in the line for gas, there shouldn't be ANY. Mine had a bad FPR, and the milage went down, also had a hard starting condition, after it was warmed up(too rich). The new FPR returned the milage I was getting. Good Luck...
 

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Discussion Starter #7
it starts fine... but it surges and gets horrible gass milage. This tank is mostly highway and its about 17.9 MPG.... usually i have mostly city (im in college and deliver pizza.... in a caddy lol) and id be lucky to see 11.5 MPG!!!
 

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White Diamond 2001 STS
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If it's surging like that, be sure to properly diagnose the EGR system. Is the valve functioning and clean? Are the passages clean?
 

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Discussion Starter #9
lol... i have no idea where the EGR system is on this car... on my old 5.0 is was easy to find... where do i start looking and what do i check?
 

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White Diamond 2001 STS
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It's just as easy with the Northstar. Look under the intake tube, and back towards the firewall a little bit. You should see a silver canister...with a black plastic cap probably. It's about 2" in diameter and perhaps 5" tall.
 

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Better find out or replace the cat converter. When they plug up, the engine cannot breathe properly through the screens. What is your mileage? How about sparkplugs, dirty or clogged fuel filter. Also a collapsed muffler can cause that.
 

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Discussion Starter #12
spark plugs are brand new the old ones fouled out really bad.

where is the fuel filter on this thing? i cant find it! lol I looked the other day but no beans.
 

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i had that surge youre talking about. for me my engine light came on, and i had it diganosed. it was some camshaft sensor, it cost me 300 to replace...
 

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Thank god I did a Honda INsight engine swap on my seville..... j/k, but wouldn't 65mpg be awesome. Ah well, back to work.
 

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Discussion Starter #15
ummm... im guess ig if you put anyhtiong other than that V8 in youer seville the milage would go down.

example: in tbird's the 4.6 V8 actually got better gas milage than the 3.8 V6. the reason: the v6 had to work so much harder to move that 1000 lbs than did that v8.

I bet if you were able to put a v6 or an I4 in your seville you would get much worse milage..
 
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