MaxiNone

iTrader: (1)

Alright, just like the title states I'm getting crappy mpg's out of my 99 gxe. When I bought the car it had 200k and ac worked and I was pulling 25-26mpg or about 470+ on a full tank. I drive like a grandma so having a lead foot isn't likely. Now I get about 19-21mpg or about 380 miles on a full tank with out ac (bypassed ac compressor with smaller belt) and I still drive like a grandma Here are the specifics and things I've done; its auto and it has 252k miles, I've change the plugs, vc baskets and cleaned out the egr valve all within at 250k. Also my cel is on (its been on since I bought the car), now the read on the cel is for an o2 sensor that's been missing since before I got the car (and I know that's not the reason why I'm getting crappy mileage) also I've changed the coil pack on the 5th cylinder due to it miss firing and it also caused a reading ln my cel before I've changed it. Here is the the story on that, I changed the coil pack and it stopped miss firing. I cleared the reading with an obd reader and my car started miss firing again BUT when the cel came back on the car stopped miss firing. The cel now reads that the 5th cylinder is miss firing when its actually isn't. Is this the reason why I'm getting crappy ac? I don't want to reset the cel and the car starts miss firing again and then the light comes on again then the car runs fine.

Any advice on how to solve this problem will be greatly appreciated...

Trini Boom

iTrader: (5)

IMO, I would say both issues are giving you the crappy MPG...unless the O2 sensor that is missing is the rear O2 sensor. Misfiring would also give you crappy MPG. You may have to replace the coil packs...

kingw323

Have you had to replace any injectors? Could be injector number 5.

MaxiNone

iTrader: (1)

Yes it is the rear o2 sensor, and like I said that light has been on since i got the car and pulled still 25-26 mpg with the ac on. I changed the coil pack that needed changing but only miss fires when I reset the cel/ turn it off. After it turns back on the car runs normal but I still get 21 mpg max. I assume it still reads the miss fire on the cel and that's why I get the crappy mileage but how do I fix that if its not actually miss firing?...

Trini Boom

iTrader: (5)

It can still be misfiring...did you check the injector on that cylinder? It may be sticking thus creating the misfire.

cashoit

prolly need a bottle or two of chevron techron. injectors and o2 could be dirty and chevron will clean that right up.

But it IS a 99, prolly coilpacks,

Trini Boom

iTrader: (5)

it never fails...

Kenneth Joseph

I too had the CEL on and was getting poor gas mileage of about 21mpg. Based on recommendations in the forum, I changed all 3 right bank coil packs, and both front O2 sensors and then reset the CEL on my 1999 SE 5-Speed....Now the car is super strong again and gas mileage is back up to 26mpg!!!!!!

MaxiNone

iTrader: (1)

I fill up with vpower from shell and nothing else, is that techcron bottle a really good injector cleaner?...

FallenOne

iTrader: (17)

Search Chevron Techron in the 4th gen forum, your the source of most of it.



Dude, Its a Maxima your fuel economy will always suck.

MaxiNone

iTrader: (1)

I'm not trying to get 30 35 mpg out of it, I just want my 25 26 mpg back. If I'm getting 20 21 I might as well be driving a v8...