13 MPG Fuel Economy at City?

My GTP give me 12.7-13 MPG at the city, i thinks is a poor fuel economy, but what do you think... What can be?

Thanks

Id start with the basic change of fuel filter,PCV,plugs.If the plugs you have now are colder then stock,once they get old that can also cause poor MPG........~Larry~

Yes, that's low. I get 21.0 mostly city driving.

Do you race it around everywhere you drive...even still that is ridiculously low. Get a new air filter, fuel filter, check spark plugs, tire pressure and try shifting lower(don't floor it w/ auto)

The air filter is a new K&N fenderwell intake (this gains me about 1 MPG more), fuel filter is new too, spark plugs are Autolite 104's at 0.60. How about PCV, what's that?. Is a lot of gas!, can be a bad sensor (crankshaft, or something). The injectors was recently professional cleaned.

Help!!!!!

yeah im with u man. im gettin 15.9 and when my dad used to drive it he got like 21. i sometimes race alot but still im gettin horrible gas milage.

My 02 GTP doesn't get the greatest mileage around the city either.. According to the read out, about 14 mpg's.. But on the highway, it gets around 28..

It seems like the torque converter is loser than most "stock" cars that I have driven.. A lose converter is great for quick acceleration, but sucks when it comes to gas mileage..

Once it's up to speed in 4th gear and the converter locks, it's stall speed is a non-issue.. But light acceleration off the line, seem to give more rpms than is typical in regular passenger sedan..

Well, it isn't really a regular passenger sedan, it's a sporty midsize. These cars are built with performance in mind, that's why they've got quicker acceleration. But even so, I'm still getting about 20 MPG, on little country roads out in the sticks, and racing around everywhere I go. If I get out on the interstate on a long trip, I have seen 25-26 MPG. Even with mods, I'm thinking 13 MPG is really really low. I'm fixing do a full tune up on mine, I've only had it like, 2 months, but I don't know how long it's been since the last one, the guy we bought it from didn't say. I'm hoping my mileage will get a little better when I do, what with the way gas prices are right now.

My tire size can be part of the problem?... My actual tire size are 235/55/R16... i think the tire size can be right?...

Help!!!

How about PCV, what's that?.

CLICK HERE (http://macgp.clubgp.com/howto/pcv/pcv.html) for instructions on changing the PCV

I've changed the PCV Valve, and no results... =(

How about tire size?

How about tire size?

The tires you have arent that much different then stock and when you are traveling 60mph you are actually traveling 59mph,so I wouldnt think that would be your problem.......~Larry~

Well I get 19-21 MPG on city driving. Are your injectors working properly? Sometimes when they mess with them, they do not lock completly when they are supposed to be closed. So check the injectors

have you checked you O2 sensor to see if its reading properly? sometimes they'll give false readings and there wont be any ses code given to tell you about it. they say your suppose to change them every 75k no matter what.

my 95 gp has a 3.1 in it...i race around a bit too, filled up today and i got 19 mpg...and thats with a little tire smokin after school and all that fun stuff, drivin one of the faster cars to school is fun....but mine at 19 racin around is ok i think...with the bigger 3.8 or 3.4...whichever you have you will have worse gas mileage probably, then concider newer technology in injection and stuff, then you still havent even concidered that its a GTP...that means its supercharged...supercharged=more air, more air makes it want more gas...see where this is goin...? 13 seems right if you are really racin around alot...

Yea right after i fill up my car and reset the mpg meter i get like 15 at most, but when i reset it on the highway i get 28 or so. is mine broken too? you are all saying 19 at city, and mine is at max 15, usually 13-14

I have changed the Fuel Filter, and the MPG are around 16... but i think still low MPG's

Thanks

About the O2 Sensor, what are the normal readings of the O2 Sensors?. I have a friend with a OTC tool, and i need to know what is normal readings.

Thanks

IIRC they are around 850 / 880 and not sure what size pulley you have on,but when I had tried 2 colder in plugs with a 3.4 I got crappy miles and went to 1 colder and it brought it back up to 21 mpg which is both city and some highway miles....~Larry~

the readings for a good O2S should be at both ends(0 to 300 and 600 to 1000 mV). if most readings are in the middle than the sensor isn't working right.

the o2 sensor are right... Replaced 1 fuel injector, fuel filter and PCV, the car ups to 15 mpg, i live in small city. The car doesn't have SES Light any more. Thanks all for your help!...

Thanks again ...

Did you actually calculate your gas mileage or are you going by the read-out on the DIC? 13 is lextremely low. I get 10mpg while running for the evening at the race track.

i saw it on DIC, Im going to calculate!

Thanks

I've got a 2002 GT, and when I first got it from the dealer (December 2003), it got really crappy MPG. I figured that it's 'cause it was built in Jan 2003, and sat at the dealer until December I figured that things were a little gummed up.

I put in a K&N stock air filter, ran around 5 tanks of permium with injector cleaner, and also periodically drove some in second or third gear holding the engine RPMs to aroun 5K once it was warmed up. After about a 2 weeks of this, whatever it was cleared up and I started getting better MPG, between 17 - 20 city and 24 or above for highway (depending where you set the cruise).

Perhaps the situation is similar to your, and this will help you out. If not, feel free to ignore :p

Erik.

I have a 1997 GTP, gets around 16. I have two 1998s. One gets 17 (with air box and 3.4" pulley) and the other gets 16. They all get around 26 on the highway. Now, I have a 1966 GTO that gets 4.5 in the city and almost 9 on the highway. I wish gas (prem) was still 22 cents a gal like it was in 1966!!

I have a 1997 GTP, gets around 16. I have two 1998s. One gets 17 (with air box and 3.4" pulley) and the other gets 16. They all get around 26 on the highway. Now, I have a 1966 GTO that gets 4.5 in the city and almost 9 on the highway. I wish gas (prem) was still 22 cents a gal like it was in 1966!!

Oh don't we all wish with for those gas prices! Come to think of it, I'd take the 66 GTO too! :iceslolan

Bought the GTO in Oct. of 1966. Drove it one day!! Seeing I was living in Michigan at the time, it snowed. Next time it made it to the road was June of 1967. Had to wait for the salt to be washed away with the spring rains. Didn't want it to have any salt around it. Uncle Sam called me up in July. Car was stored till July 10th, 1969. Then it was worth too much to drive. Shipped it down to Florida 3 years ago, no air,too hot to drive, still in "barn". Makes a lot of shows. Drive it about twice a year. Thought about selling, once. The was the longest 10 mins of my life.

Hang on to that car!

Store it in some hermetically sealed container garage!

It's far too valuable and rare, now adays, to even take a chance at having some idiot, unskilled driver whose not paying attention to hit it!

Only available for 4th July parade (do some burnouts for the crowds!)

Well, IMHO anyway. ;-)

MUST read again, I live in Florida. Down here the run into parades, and buses, and air planes and... Goes the shows in trailer. And if they don't get any better down here, with their driving skills, I'm going to make them hold the show at my house.

I think your city mileage depends on the kind of city driving that you are doing..GM rates Grand Prix's at 18 MPG city.. That's on a course that they consider represenative of city driving.. If you're going thru a lot of close together stop signs and lights.. Your mileage is going to completely suck..And if your doing a lot of idling, that's "0" miles per gallon.. And it figures into the average..

My 02 GTP gets terrible mileage in the stop and go enviorment of living in the city.. But on the highway, I can go almost 100 miles before the gas gauge needle comes off full..

This past week, I got a flat on the rear of my car.. And with the donut spare on, and only running between 50 and 55 mph.. I was pulling down 34 MPG :eek: on the highway... Typically, running around 70 mph with the A/C on.. I'll get about 28 MPG..

You know that the "top" part of the tank, if you fill to the top always takes a lot longer to use then the bottom. GM dumps two gals of gas in test car and runs the car. Most will get 28 to 30 highway. BUT with an air box, 3.4 puley, reworked heads, headers and a lead foot, who knows and cares. Lets have fun out there and be safe.

My car is on the mechanic shop, they has reworked heads, new fuel injectors, new coils, a 3.4 pulley, ported & polished blower, new zzp coupler, new sc oil, tb spacer, cold air intake with 9' K&N, NGK TR6, and other stuff... I think my low MPG problem was a cracked heads, but i hope when it be ready get more MPG than 14 or 15 in city.

I have some picts of my GTP in my member gallery... When they be ready i post some pics.

Thanks

My car is on the mechanic shop, they has reworked heads, new fuel injectors, new coils, a 3.4 pulley, ported & polished blower, new zzp coupler, new sc oil, tb spacer, cold air intake with 9' K&N, NGK TR6, and other stuff... I think my low MPG problem was a cracked heads, but i hope when it be ready get more MPG than 14 or 15 in city.

I have some picts of my GTP in my member gallery... When they be ready i post some pics.

Thanks


Hey cracked heads will do it everytime. I have to say though that combined slow going city traffic combined with stomping on it once in a while will get you low gas mileage even well under 15 mpgs - I've seen it. I picked-up a 2000 Bonneville SSEi (@ about 285 hp now) and couldn't believe how good the mileage got after I took a break from traffic, peelin out and racing it every chance I could. Gets 32 mpg at 60 and 30 mpg at 70.

Hey cracked heads will do it everytime. I have to say though that combined slow going city traffic combined with stomping on it once in a while will get you low gas mileage even well under 15 mpgs - I've seen it. I picked-up a 2000 Bonneville SSEi (@ about 285 hp now) and couldn't believe how good the mileage got after I took a break from traffic, peelin out and racing it every chance I could. Gets 32 mpg at 60 and 30 mpg at 70.


Damn, you had to dig to get this one out.

7/04. Almost a year. :banghead:

Damn, you had to dig to get this one out.

7/04. Almost a year. :banghead:


Yes I had to dig because I can't seem to find reliable information on how much I am going to get killed on gas mileage, on both city and highway, if I install a 3.4 or 3.25 pulley. One source said some get better gas mileage. I am also having trouble finding out if there a reprogrmmed PCM out there for my 2000 Bonneville SSEi -- it's the L67 supercharged just like any other -- I think???.

I was getting around 18.8 with the 3.4 and aftermarket PCM.Stock from the factory our cars were rated at 18 city/28 Hwy.

I am also having trouble finding out if there a reprogrmmed PCM out there for my 2000 Bonneville SSEi -- it's the L67 supercharged just like any other -- I think???.

Check out this site,ZZP , they sell a DHP for the Bonny.

http://www.zzperformance.com/products1.php?id=182&PHPSESSID=7eb00f9a712ec8f08d7ceee536162c07


~Larry~