hey guys so lately i have relized that my sc has been getting really bad gas MPG like about 11 miles per. and i have been scratching my head about it what could it be i dont know to much about the problem. the only things i can come up with are vac lines. my car does run healthy just has a slight exhaust leak any ideas on what it could be?

thank you

 

Damn!, are you always on throttle?, uh things like air filter, maybe maf clean out?, tire pressure, check some of those things?

 

i drive conservitave i am 17 makeing minamum wage i wish i could full throttle it alot ha but the fuel filter has been changed i cleaned the intake a month ago along with new plugs and wires i leak nothing any where thats why i am so dumb founded

 

in addition to the things mentioned....bad injectors...stuck brake caliper....

 

i never thought about injectors thats a good one any preference in brand that has the best live time and performance?

 

Before you go to injectors, check stuck calipers first, then o2 sensors. Pre-OBD2 SC's, don't throw codes when o2 sensors misread.

 

good call on the o2 sensors....reminds me of a potential bad catalytic converter.

As for injectors, I would try some cleaning formula that you dump in your tank before you ever go through the hassle of swapping them out.

 

possible bad plugs too. take them out and check them easy fast

 

17 with SC,what year?. Have you had a tuneup done on the car?

 

[QUOTE=KingPhilip;7800811]Before you go to injectors, check stuck calipers first, then o2 sensors. Pre-OBD2 SC's, don't throw codes when o2 sensors misread.]

i have a 93 and its obd1 how do i kow if the o2 sensors are bad?

 

i have a 93 ^^^ and i have done a full tune up about a month ago plugs wires oil ect.

 

[quote=2jzNoshizz;7803053]According to one thread I read, o2 sensors for preOBD2 Is part of maintenance and should be replaced every 80k miles. So I did everything when I had the same gas mileage issues. I used to get around 11-15MPG's.

 

I would try some cleaning formula that you dump in your tank before you ever go through the hassle of swapping them out.

 

run car to 1/4 tank take half bottle of seafoam into tank then fill up.. i have a 92 sc400 and im averaging 24 in the cold and close to 30 when warm/hot out.. so ya thers something going on.. what kind of parts did you use when you did the tune up

 

Well usually a good tuneup will help.

- Check spark plugs
- Check wires
- Check distributor cap and rotor
- emissions removed or working properly ? bad egr can cause issues as well
- Check 02 sensors ( I ran 2 universal bosch sensors on my 93 and it helped with idle and mpg )
- Make sure air filter / maf are both clean ( you can buy the CRC maf cleaner at any local parts store - Advance Auto usually keeps em in stock )
- Check for any other engine related issues.
- Hows your catalytic converter?
- Check stuck brakes including emergency brake
- Bad injectors ? could be stuck open?

How does the car feel driving?