only 18 mpg

[rruddfan21]

how can i improve this? it has 113,000 miles on it, and everything seems fine. just bad mileage. thanks in advance

[geozukigti]

Detach the boat from the back of it?? Do a tune-up. Plugs, wires, dist cap and rotor, o2 sensor. Also, try not shifting @5000rpm's, heh.

[rruddfan21]

well i was assuming it was because i always run around talladega and also i ran it in the cup race a few weeks back LOL no really this is on my list of replacements...
*spark plugs
*plug wires
*pcv valve
*o2 sensor......question on that. is it easy to locate and replace? do you need a specific socket to detach it?

also, a quick question (i admire the fact that you know so much, i am an aspiring technician that enjoys reading your diagnostic skills anyway in december i had a new resonator and tail pipe put in the exhaust system. however, when i run the car and then shut it off, it smells like something burning or exhaust under the car. when my tranny slipped, it was shown that a very minute leak at the rear of the tranny was present, but i don't think that it would cause it to smell everytime i run the car. is this it, or do i have a small leak in exhaust? doesn't run loud however when i accelerate i do hear quick, periodic raddling from bottom of car (nothing is dragging). thanks in advance!

[mcalvo]

rruddfan21:
The O2 sensor is located right after the mannifold (exhaust engine exit), it merely looks like a plug. You have to be careful: do not remove it when the exhaust is hot (even warm), hot makes the metal flexible and you could screw the hole thing and then you should take your whole muffle out to get it fixed.

A tip, if O2 sensor is to tight, use an acetilenum torch to hot its base to red, then get it cold using just a hose. Be sure to unplug the source cables before, to prevent them to get melt.

Hope this would help you. My english is not good and I am still learning.

Good luck!

MC.

PD: Please tell me where you get the PCV valve and how much was it. My Geo is running low MPG too.

[geojim]

A check of timing and compression is also in order. Did the gas mileage drop suddenly, or was it always bad? Did it go down slowly or take a nose dive? Time wise, can you match the drop in mpg to other work done on the car? Jim

[rruddfan21]

mcalvo- thank you. i am going to get my pcv valve at advance auto, and i believe it is around 5 bucks. i wasn't sure how easy it was going to be to replace the 02 sensor, and i wondered if you need a special socket to remove it??? anyway, i really appreciate the help. thank you

geojim-well, i've had the car since december, and i noticed i had to fill it up frequently. it is a used 91 metro, and it has had this since i've owned it. nothing else is wrong with the car, really. no weird smoke out the exhaust, nothing bad in the tailpipe, it responds when i want it too, and everything seems okay. but since i bought it used i'm not sure the last time it has had a tune up. that's why i'll replace a lot of stuff on it. i was going to replace the fuel filter, but do you think it is okay since i'm getting so much fuel? also, i don't have a ignition timing scope and i don't have the money to buy one, so can you see timing by looking at the timing marks? thank you

[geozukigti]

Well, ignition timing, and cam timing are 2 different things. You can borrow(with a deposit) a timing light from most auto parts stores for free. Also, a higher voltage coil works good. I personally use an MSD Blaster II coil. Only $45, and it's a 50k volt coil. A little more power, and a very noticable jump in MPG. Pair that up with some NGK wires, and Bosch Platinum +4 plugs, and you'll have a smooth idling, nice running, better MPG car. Also, don't forget to change out the cap and rotor. You can lose a LOT of spark on a bad cap and rotor. I would recemmond changing a fuel filter every 36k miles just to save the stress on the fuel pump. Fuel pump's are a BITCH to fix on these cars. As long as you're giving it a tune-up, clean out the intake with some carb cleaner. I would recemmond having the engine off when you do that. Open up the throttle body, and spray down everything you can see. Then start the car up, let it idle and burn out the carb cleaner before opening the throttle. If needed, goose the throttle to get it to start. Also, run some fuel injector cleaner in the gas.
If you can get the tool, run a compression check on the cylinders. They should be about 170-185psi across the board.

[rruddfan21]

well, if i had the money, and the desire to do that much work on the metro, i would. but i have to stop and think just that...it is only a metro (i saw your's, worth the input, but i have a used 113,000 mile four door hatchback) and i don't want to completely redo everything. besides, this time next year i'll be selling it. however, from your advice, i am going to do the following:

replace fuel filter
replace plugs and wires (i checked cap and rotor, look new)
replace 02 sensor
replace pcv valve

this will allow me to learn and also help out the car a bit. one last question...where the hell is the pcv valve? there are multiple hoses and what not coming from throttle body, and i'm not sure which is for pcv (i recognize the fuel hoses)