Somone PLEASE help!!!!

[Johnomx3]

Someone please help me... i have a quite stock 92rs, 4cly 16 valve SOHC... Anyways my gas milage is horrible.. i bought this car off my best friend about a month ago and a few months ago the car was excellent on gas... im talking 600km per tank, now i seem to get about 150ish per half tank... so about 300 per tank which is half of its potential.. anyways I really need some help, theres a magnaflow street series muffler on it, im not sure but i think the gas milage started getting worse when this muffler was added. other than the muffler the cars engine and all that is perfectly stock. Someone please help, email me or msn me at johno_brownrigg@hotmail.com or post with your thoughts... i really dont know much about engines and really need this looked after.. any info is good info.. Please help me and my poor Mx3... you think the lil 4cyl sohc would rock gas milage.. anyways awaiting your help. Johno

[Typhoonk]

copied from :->http://www.ehow.com/ehow/ehowDetails.jsp?id=2629
-------------------------------------------------
Here are some tips:

1. Check your tire pressure. If it is too low, add air to bring tires to their recommended pressure.

2. Check your air filter. If it is dirty or old, replace it.

3. Run your car's air conditioner less.

4. Drive calmly. Avoid unnecessary acceleration and braking.

5. Plan more efficient routes if you drive in traffic.

6. Tune up your car if these steps do not improve your mileage.

7. Ask a mechanic to check the gap on your spark plugs. Adjust or replace as necessary.

8. Ask a mechanic to look for fouled fuel injectors. Replace them as necessary.

9. Replace spark plug wires.

If your gas mileage suddenly plummets, see a mechanic. Your car may have a serious problem.

-----------------------------------------------

[mxk]

Also check your o2 sensor, it may need to be replaced, its a common cause of poor gas mileage

[Ehpl]

I agree with MXK, I had the same problem an a O2 sensor fixed it right up. I think they recomend that they be replaced the O2 sensor every 75k miles.

Eugene L
1.6DOHC
N.S.canada
http://www.cardomain.com/memberpage/552384

[Johnomx3]

Thanks guys, ill look into a o2 sensor, and get a mech to check my plugs and wires... Is there any reason that the exhaust would be the cause tho? that magnaflow muffler? i want to take it off and try without see how that works, but its a lot of work "and cash" to exhange mufflers..
Again thanks

[mykel78]

Your muffler shouldn't be causing this problem. Most aftermarket mufflers just open your exhaust a little, improving air movement. Often it may increase mileage (by a small amount if just the muffler has been replaced) by getting rid of hot air from the engine bay. Sorry, I've nothing else to add...
To others: what other problems can the O2 sensor cause?

[perhapsadingo8yerbaby]

When the oxygen sensor fails, the engine ECU (computer) can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.