MPG on my 93 Cutlass convertible (3.4)

[BN]

I just checked mpg on my Cutlass and with no highway driving it ended up being 13.3 mpg. This seems terrible to me. What are you guys getting? Any ideas on what to look for if this is low?

[Crazy K]

don't rev so high? that doesn't seem too far from normal for hard city driving...

 

 

 

but, does your check engine light work? is it on? what have you done for tune-ups and stuff???

[hotrodolds]

Yeah...tune-up time. Should be upwards of 17mpg or so, really.

[xtremerevolution]

Yeah...tune-up time. Should be upwards of 17mpg or so, really.

 

For a 4000lb car with a 3.4L DOHC? I can see how a normal w-body would get that mileage, but that added weight can't be good for fuel economy.

 

Do you have aftermarket wheels on it?

[BN]

Original wheels. Service engine light works. Comes on for a few seconds here and there but never stays on for long. I'm used to old cars with V-8's and carbs. What is considered a tune up on these? New plugs, airfilter, wires,???? Anything else?

[xtremerevolution]

Original wheels. Service engine light works. Comes on for a few seconds here and there but never stays on for long. I'm used to old cars with V-8's and carbs. What is considered a tune up on these? New plugs, airfilter, wires,???? Anything else?

 

Don't forget the oxygen sensor. A bad oxygen sensor will screw up your fuel economy pretty badly as well.

[RobertISaar]

pcv as well. need to see why the SES light comes on though... if its only for a few seconds, it could be EGR. that can kill some fuel economy.

 

might want to run some seafoam through it as well...

[jake91]

full city driving and revs to 4+k at every light results in 17mpg for me

[xtremerevolution]

pcv as well. need to see why the SES light comes on though... if its only for a few seconds, it could be EGR. that can kill some fuel economy.

 

might want to run some seafoam through it as well...

 

x2 on the seafoam suggestion.

[hotrodolds]

Agreed here as well.

[BN]

What's Seafoam?

[Crazy K]

do a code check procedure. paperclip check will work for a 93.

 

you need to see what your codes are.

 

seafoam. go to wal-mart or an autoparts store. it is a can of multi-purpose engine cleaner. you would allow seafoam into the engine through a vaccum line and it will help remove gunk in the engine...

http://www.seafoamsales.com/motor-treatment/index.html

[BN]

Got some Seafoam. Any suggestions on the best way to get into engine?

[xtremerevolution]

Got some Seafoam. Any suggestions on the best way to get into engine?

 

Brake booster line. Its a big, thick vacuum hose going into your brake booster, a large usually black cylinder type thing on the driver's side. Just unplug that from the brake booster. Your engine will idle rough and might die. Turn it back on, and start pouring it in there. Once done, plug it back in, sit back 5-10 minutes, and start it up again.

 

Be advised, your car will smoke up a LOT out of the exhaust. Its completely normal, but you probably shouldn't be inside a garage or in a busy intersection doing that. There are lots of youtube videos about this.

[RobertISaar]

Brake booster line. Its a big, thick vacuum hose going into your brake booster, a large usually black cylinder type thing on the driver's side. Just unplug that from the brake booster. Your engine will idle rough and might die. Turn it back on, and start pouring it in there. Once done, plug it back in, sit back 5-10 minutes, and start it up again.

 

Be advised, your car will smoke up a LOT out of the exhaust. Its completely normal, but you probably shouldn't be inside a garage or in a busy intersection doing that. There are lots of youtube videos about this.

 

should also add not to pour it too fast or you can hydrolock the motor... and don't leave it sit too long or else you can foul the spark plugs... i've also done this with the winter formula windshield washer fluid, seems to accomplish the same thing but requires a larger amount of fluid...

[BN]

Did the Seafoam. Car runs smoother, just need to check mpg to see if any improvement.

[Crazy K]

how about that check engine light?

[19Cutlass94]

I get 15mpg around town in my truck. you should deff be getting better than me.

[BN]

Didn't get to the check engine light yet but mpg is 17 after the Seafoam.

[Crazy K]

 

READ:

http://www.extreme-check-engine-light-codes.com/GM%20OBD1%20Decoder.htm

 

and a paperclip will work for a jumper wire.

each code is repeated 3 times, then the next code, and then the code loop will start over. You will always get a code 12 before other codes.

[94 olds vert]

I recently got 14.7 mpg in the city in my cutlass. All city driving.

[xtremerevolution]

I recently got 14.7 mpg in the city in my cutlass. All city driving.

 

Then there's definitely something wrong with your car.

[jake91]

Yeah...tune-up time. Should be upwards of 17mpg or so, really.

 

For a 4000lb car with a 3.4L DOHC? I can see how a normal w-body would get that mileage, but that added weight can't be good for fuel economy.

 

Do you have aftermarket wheels on it?

 

 

 

I recently got 14.7 mpg in the city in my cutlass. All city driving.

 

Then there's definitely something wrong with your car.

Very contridicting statements LOL

[xtremerevolution]

the vert would obviously get worse gas mileage, but I then realized that 14mpg really is pretty bad.

[Fmr12B]

The 3.4L Cutlass Vert's are rated at 15mpg city per the EPA's website.

 

With lots of stop & go traffic, and short trips, I average about 15mpg.