Bad fuel economy

Bad fuel economy

Hey guys,

just wondering why I get such a bad fuel economy from my '95. It's a 1.3L 2E engine (im from South America). I always keep my engine well maintained. Plugs, cables, clean a/f filters, properly tuned carb, dist cap, rotor, oil, no unnecesary weight, etc.

Only addons I've made are 2" exhaust pipe with resonator and muffler and 17" rims. I've read that bigger tires affect on odometer/speedometer reading. On my case that would be about 5 miles error. With that I'm currently getting an average of 27mpg (city) and 29mpg (hwy). Would you consider this normal or is there something wrong?

Any suggestions r welcomed!

Thanks!!

do u haev a/c and use it a lot?
do you drive the car hard?

oh yeah, I rarely use the A/C to save a few gallons, just when it's really necessary. During city driving I shift below 4k, most of the time shift at 3k. My common runs are around 15kms daily at an average of 45mph.

I think your 17" is one of the big problem.
How heavy are those 17"? I find that I can save a lot of gas when I'm on my light rims.

I am seeing two problems here. First, those 17s are the major problem. They are heavy to begin with and then they have a wider contact patch than the 13 inchers the car perhaps came with. This will add drag through rolling resistance (contact with the road) and wind resistance (contact with the air).

Another issue is with your exhaust. Your engine was made to make use of a certain amount of backpressure. A larger exhaust system lowers the backpressure and will normally affect the engine's performance in a certain rev range. Chances are your exhaust system is not properly tuned for your driving habits.

What other thigns do you have in that car? A huge sound system perhaps? Neon lights? DVD? PlayStation? BBC's Top Gear and Discovery Channell's Myth Busters proved that using excessive electrical items lowers your fuel economy too. And the weight of a huge sound system will also affect fuel economy. (Top Gear took an Audi A8 4.2 V8 TDI from London, England to Edinborough, Scotland on one tank of diesel. That's 800miles!! They had to do without all electrical devices, a/c and the radio included).

With regard to the speedo error, most cars have an inbuilt error of between 5 and 10 mph high...that means when you show 80mph you are actually doing 70 or 75. Bigger tyres will do the opposite. The error they give is one that is LOW. So if you have a speedo error of -5mph and a tyre error of +5mph you are actually doing what is indicated.

Hey thanks a bunch for the replies guys!!

The 17s are 27lbs each w/o tires. They are way very heavy. I'll switch back to the 13s for this week to see how it goes!