Im getting less than 10 miles per gallon on my S13

[jsr20det]

I filled up my car to the top yesterday with 89 octane, and topped it off with some STP gas treatment thing, and STP fuel injector and carborater cleaner. Welll, the reason why I put that is because I was getting bad gas mileage and my friends and mechanics suggested them.

So I after I filled up, i reset my odometer checker thing so I can see how much I drove. Well, yesterday I drove for 10 miles or so, and today, i drove my friend to UIC and back, my odometer says 48 miles so far, i live near skokie, so im not sure if thats right or not, but in any case, it cant be that far off.

I looked at my gas, and i saw it just a little above half a tank mark. I dont understand how I wasted 45% of the gas already in only like 2-3 hours of driving tops, and I kept it under 3000rpm most of the time. My friends tell me that my exhaust stinks and that sometimes it shoots out black shoot when i punch it. Wats wrong with my S13???? I just put in new OEM NGK spark plugs gapped .041, and I have a GT-Spec style tip exhaust with 2.25 inch piping from the cat converter.

[Yoshi]

your name implies you have an SR, but your mods sound like KA, which is it? Little specifics like what engine you have can make all the difference ;)

[AKADriver]

Check the MAF and its connector, and check for vacuum leaks.

Folks, it's not his tire pressure if he's blowing unburnt gas out the exhaust. Obviously something's causing his engine to run rich. Doesn't sound like an O2 sensor problem since it still happens on acceleration. I'd say it's most definitely the MAF.

[jsr20det]

Sorry about the confusion, I have a KA =]. I just recieved $400 for new rims and tires to replace my current ones. My current tires (http://home.earthlink.net/~jgoo3030/images/Cars/240/DSCF0014.JPG) are really bad, so I was hoping I wouldnt have to spend any money on my current problem but its gonna end up costing me more in the long run. Also, on the label of the STP treatments, they said it was ok to mix two stp products.

I was having bad mileage when I first bought the car, but for a grand, you cant go wrong =]. Also, when I opened my hood, I didnt notice but there was an o2 sensor just hanging on a piece of plastic (according to my friends). So my o2 sensor is in my friends garage. My friend tells me that I have one already in my engine, or else the check engine would've came up.

Im missing an o2 sensor, or my catalyc is dead is wat im guessing, but I could be wrong. My mechanic said that the cat is brand new, so i think i need that o2 sensor, should I buy a new one or just put my broken one back in? I had a friend of mine install the a drop-in cone, but i made him put the stock one back in for now, maybe he forget to connect something?

This is my first car and only had it for a month now so I would like all the help I can get.

James, my friend just bought a silver S13 just yesterday so count me in, along with one more S13, can i get more information about the meet also? Hope to see ya soon.

[AKADriver]

Dunno about yours, but my 1990 doesn't even HAVE a check engine light.

Dead cat wouldn't kill mileage. But running rich for months will kill the cat.

The S13 only has one O2 sensor, if it's not installed you'd have a serious and noticeable exhaust leak.

It still sounds like the MAF to me especially since you've been diddling with the intake tubing.

[DuffMan]

Your car doesnt have a check engine light, at least my 90 SE doesnt.

You probably need the o2 sensor back in. Someone should bring tools to the 4th meet and we'll fix it. Also the ecu has a o2 sensor real-time monitoring mode that can help track these things down (not sure if the Ka24e has it but i think it does).

[sykikchimp]

MAF or fugged up, broken leaky injectors.. I would almost bet on the injectors before the MAF just because it's such a common problem with the KA24E.

[uiuc240]

keep in mind that it could also be:

fuel gauge
- or -
odometer

If the fuel gauge is funny, it might read low for a while, then not move, then move again (like mine). That can probably be fixed by buying a new sender for the tank. The odometer could also be sticking, which would cause everything to read slow.

To check that, drive on the freeway and check the odometer against the mile markers. Best way would be to drive about 10 miles (by the markers) and see how much the odometer changed. If it's around 10, you're ok...

Eric