ive been gettin a steady 10-11 mpg under relaxed city driving. i just recently put in new o2 sensors. i had a CEL for a lean engine, but it was running rich. no more light since i put them in so id assume it was fixed, but no... no dif in mpg. although there are no more codes and it does seem to run a bit better. what else could cause this, as far as i can tell there are no vacum hose leaks, at least nothing major i can hear over the engine. but overall the car runs great, so im really confused why its doing this. thanks alot
horrible gas mileage
- Thread starter laxmax327
- Start date
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1992SHOMTX
Vrrooommm...pssshhhh
are you doing preventative(sp?) maintanence? like oil changes air filter spark plugs(not often...) and whatnot. that could rob some mpg. other than that im not sure...do you beat on it much? and just out of curiosity what grade of gas are you using?
yes, the oil is always changed, has a good kn filter. have yet to change the spark plugs. dont know quite how to do the back ones and never had a reason to so didnt bother really. usually my driving is pretty tame, but of course i open it up here and there. and im using 89 octane. its a 92 mtx, should i try the plugs? how do i get to the back ones?
SASHO91
Zoom Zoom
2 ways...
I prefer pulling the intake... much easier once its off. No hurt knuckles, and whatnot.
Plus after you take the intake off you can clean that as welland bypass the TB coolant lines... if its your first time taking the intake off, either make notes, or take video (kinda extreme, but hey it works) that way you know whats what...
I dont mind pulling the intake as it only takes a few minutes to pull off...
and the rest is simple. changing the plugs, and putting th intake back on. As you dont have to worry about those pesky coolant lines. (if you do the TB coolant bypass)
also, what other maintance has been done to the car? has it had a 60K? or 120K?
are your brakes sticking?
theres a few to keep you occupied for awhile...
I prefer pulling the intake... much easier once its off. No hurt knuckles, and whatnot.
Plus after you take the intake off you can clean that as welland bypass the TB coolant lines... if its your first time taking the intake off, either make notes, or take video (kinda extreme, but hey it works) that way you know whats what...
I dont mind pulling the intake as it only takes a few minutes to pull off...
and the rest is simple. changing the plugs, and putting th intake back on. As you dont have to worry about those pesky coolant lines. (if you do the TB coolant bypass)
also, what other maintance has been done to the car? has it had a 60K? or 120K?
are your brakes sticking?
theres a few to keep you occupied for awhile...
khanartist
oldtimer....
One thing to keep in mind is that engine sensors can be at the extremes of their ranges and not throw codes. The MAF in my car was going bad, but didn't throw a code for a long time. Before it did, I was getting bad gas mileage too. Not saying that you should go and change sensors here and there but as long as everything mechanically is in good order, you might have to get involved with them.
SASHO91
Zoom Zoom
oh yeah, forgot about that...
buy some electrical sensor cleaner.... and clean the MAF... forgot you were running a K&N...
buy some electrical sensor cleaner.... and clean the MAF... forgot you were running a K&N...
SeanMc
NoMoSHO
I noticed that it's also the type of gas I run. I filled up with Arco premium fuel, and got the best gas mileage I've ever gotten, 320 miles when light came on. Filled up, still had 4 gallons left. I went to 76 the other day, and filled up. 200 miles later, and my low fuel light is on.
1992SHOMTX
Vrrooommm...pssshhhh
ive also noticed when i use 89 i dont really get the best gas mileage. when i use 93 its actually pretty good. (btw i also have a 92)
Gen3
New Member
err...bypass coolant lines? are there any benefits from doing this?
F-22 Raptor SHO
New Member
Mileage at 10 to 11 mpg is horrible (even for atx city driving)
First check the codes for a senor problem. Does the car run fine other than the bad mpg? If there are no codes pointing to a bad sensor Consider the following causes:
1: Sticking e-brake cable. Jack the rear wheel up and turn it....is it sticky?
2: Is there a noticeable loss in power? Perhaps your cats are clogged or a piece broke off and is blocking your pipe. You can disconnect the y-pipe and take a peek.
Other issues like low tire pressure and excessive weight in the car, poor maintenance will influence mileage, but individually they wont rob you by more than a couple mpg unless it is an extreme case of either situation, so it could be a combination of things.
Check the easy things first, (codes, rear wheels, tire pressure, the weight of your right foot on the pedal).
First check the codes for a senor problem. Does the car run fine other than the bad mpg? If there are no codes pointing to a bad sensor Consider the following causes:
1: Sticking e-brake cable. Jack the rear wheel up and turn it....is it sticky?
2: Is there a noticeable loss in power? Perhaps your cats are clogged or a piece broke off and is blocking your pipe. You can disconnect the y-pipe and take a peek.
Other issues like low tire pressure and excessive weight in the car, poor maintenance will influence mileage, but individually they wont rob you by more than a couple mpg unless it is an extreme case of either situation, so it could be a combination of things.
Check the easy things first, (codes, rear wheels, tire pressure, the weight of your right foot on the pedal).
well i havent had to car for long, so cant be positive about any maintenance. but supposedly it had the 60k done at like 80k... and has 112k now. and i really have no reason not to believe it. car runs excellent, very responsive and powerful. just the damn mpg. i checked the codes, and there are none anymore since i replaced the o2 sensors. ill check the rear wheels later. but i doubt it, the car will roll on even the slightest incline. im goin to pump up the tires and fill it up w/ 93 next time and see what happens. o yea, dont know how i forgot, when i bought the car, it had a completely shot front mount. so dunno for how long he drove it like that, and i drove it for a week like that. very very modestly though of course. but after i replaced it. i found lots or wires and **** broken. like one of my o2 sensors wires wasnt even connected. i have no clue how the car even ran. so many things werent even connected. i believe i have fixed them all now, except for one, but i believe it is just the abs. its in the back left, near that abs test box thingy. like 6 inch down the wire from that box there is a wire connection w/ 5 wires, their all ripped out, and theres not enough wire to reconnect them, i need to find a new connector. but like i said im pretty sure it just the abs, if someone could check thatd be great.
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