poor gas milage

I have a 93 geo metro LSI rag top with a manual transmisson. It has 125k milage and I am only getting 20 to 25 mpg. I have had the car sence 50k milage and it has always been the same. I have just replaced the spark plugs, wires, rotor, rotor cap and timing belt. I still have 20-25 mpg. What is going on?

do you drive it hard? Do you live in canada like me? I have to keep the defrost on all the timea dn this has dropped my milage down to 31 mpg in winter months but in summer its at 40-45mpg. I have the same car as you rag top too. I just got the timing belt done, plugs, wires. I put a little Lucas oil in too to coat that poor 3 cyl. Tire pressure ok? Check the basics, if everything is ok then somethigns wrong.

Yea, mine is about the same and it runs good when it's warm. It loads up bad when it's cold. To date, I have a new ECT, TPS and O2 sensor. The only thing left I can guess, is having it plugged into a diagnostic computer and see that all the parameters in the ECM are correct. If there are code errors in the car's computer, then they have to be cleared. As I understand from my Haynes manual, they can not be neccessarily cleared by unplugging the battery or pulling the tail lamp fuse.

So......if you get any ideas, please let me know too.

P.S. Mine is a 1991 4 door hatchback

do you drive it hard? Do you live in canada like me? I have to keep the defrost on all the timea dn this has dropped my milage down to 31 mpg in winter months but in summer its at 40-45mpg. I have the same car as you rag top too. I just got the timing belt done, plugs, wires. I put a little Lucas oil in too to coat that poor 3 cyl. Tire pressure ok? Check the basics, if everything is ok then somethigns wrong.

I live in Bakersfield, CA so the wether here is very, very mild and I drove one tank of gas at 55 mph and another tank at 70 mph and not much change in the mpg. Every thing you said to check is good. I am lost here.

Yea, mine is about the same and it runs good when it's warm. It loads up bad when it's cold. To date, I have a new ECT, TPS and O2 sensor. The only thing left I can guess, is having it plugged into a diagnostic computer and see that all the parameters in the ECM are correct. If there are code errors in the car's computer, then they have to be cleared. As I understand from my Haynes manual, they can not be neccessarily cleared by unplugging the battery or pulling the tail lamp fuse.

So......if you get any ideas, please let me know too.

P.S. Mine is a 1991 4 door hatchback

I think it is running very rich. When I stand behing the car when running, it smells like raw gas coming out the tail pipe rather than exhust fumes. I could be reaching here, not to say my nose is a calibrated peice of equipment :smile: As if now I dont now what the heck is going on.

The trouble codes are not a Holy Grail. There are things like a non-functioning cold idle valve that can give you grief.

In the top section of our TBI's is a piston that is controlled by a salt pellet. This pellet expands and contracts according to coolant temperature, thus moving the piston to allow more air when cold, and less when warm. Another component that wont set a trouble code is the fuel pressure regulator, vacuum leaks, and weak fuel pumps.

As for the Haynes manual - what page? I have a factory manual in case you have not noticed and it says to pull the negative or the tail fuse. Dont you find that strange?

Blake

Am I wrong to think 25 mph is not right or do these cars get this bad of gas milage after a certan amount of miles.

I live in Bakersfield, CA

I am sooooooooo sorry! I do not miss living in the armpit of california. :frown:

Even if it was just a little off you should get milage in the high 30MPG range.I would suggest checking all of your engine sensors for proper operation. Any engine codes may be helpful in finding a bad sensor and the way to get, read, and clear those codes is available in other threads here. Just do a search on codes or something similar. Chances are that one of your sensors is not operating properly and loading the car up on fuel, possibly up to 50% too much based on your mileage. If your sensors all check out then you need to check or replace the computer. I hate to throw parts at a car without knowing for sure what the problem is but most of these parts are available pretty cheap on ebay or at junk yards. When DieInterim returns (I assume he is away on vacation or some such) he has the factory manual that would have the pinout readings for the ECU that would allow you to check it's operation. Finally you can play with the timing and check your mileage while listening for any engine knock. The JDM motor I dropped into my 95 was getting very poor gas mileage initially. Everything appeared to be working so I started advancing the timing untill the mileage was in the high 30s and stopped there pending an opportunity to reverify timing marks and sensor operation. You should definately be getting better mileage so something is not operating correctly, I am actually surprised you are passing California smog regs. In TX I am so far below the required readings that I could do all kinds of mods without worrying about failing.

Good Luck!!

Bad mileage in the winter is in-evitable because of the MTBE they put in the fuel. Check your ignition timing. It could be retarded to the point where you just have to mash the gas to get it going. Check your ignition timing, maybe advance it a degree or 3. Another problem is you live in California. They actually use a different engine computer there. It runs rich to reduce NOx gasses, but increases CO2 output. Personally, what I would do is order a cheap ECU from the east coast, and plug it in. And when it comes to emissions testing time, just put the cali spec computer back in. There's also several other MPG robbing additives in california fuel. Have your cat checked. It could be loaded up with carbon because of the rich fuel mixture over all the years. Make sure your air filter is clean too. Big mistake people always make. Air filters and PCV valves are 2 little things that can make a BIG difference. Honestly, it'd be a cold day in hell you get 40mpg with a california ECU.

I bought my 95 Metro 1.0L 5sp in Los Angeles in 2000. Though I no longer live in California, I still drive the car. I routinely get mileage in the mid to upper 40s -- even when the weather is below freezing.

Just my 2 cents.

Mike

I bought my 95 Metro 1.0L 5sp in Los Angeles in 2000. Though I no longer live in California, I still drive the car. I routinely get mileage in the mid to upper 40s -- even when the weather is below freezing.

Just my 2 cents.

Mike
weather is below freezing from november-april with about 20 F on average. Winter sucks, and with snow with over a foot sometimes on the group-it aint no LA here! thats why we get 30-38 mpg in the winter at best.....yet summer is about 85 F with milage in the 50's. Later

I have mine for 4 years now the biggest thing that rub the mpg and hp is 10w40 oil you have to have 5w30 then change your air filter and put k&n and take your EGR out clean it or change it if you have more than 100k it,s costly about 78$ or just take it out clean with brush new gasket and you should be ok.I,m delivering pizza and i,m really hard on eng ,still get 30 to 33 in townand never got 45 mpgmake sure your brake are not grabbing or you e brake are not engaged or adjusted tightly,it,s only 3 cyl and less 1000 cc,any little thing can cause low gas millage

Thanks for all your advice. I came from Iowa to Bakersfield and the car still has the plates from there until I can get this problem taken care of. Do you have a part # for the computer and the cold idle valve?

You might also check this earlier post where the fuel return line was restricted causing high fuel pressure and pulling mileage down.
http://www.automotiveforums.com/vbulletin/showthread.php?t=504657