rahjah

I have a 1992 S13 that is averaging between 13-15 MPG. The powertrain is stock (except for a K&N drop in filter), automatic with 180,000 miles. It runs great has plenty of power (for a Ka). I recenlty replaced the O2 sensor and all of the spark plugs. All cylinders all getting spark and fuel. I have searched and searched and the only things that I could come up with based on what I found online were to replace the O2 sensor and the engine coolant temperature sensor, which I did. So far nothing has helped. I a fairly long thread on Zilvia.net about fuel mileage and was unable to resolve my problem. If anyone has had this problem and fixed it I would love to know how. Thanks in advance.

iLagX

timing?? spark plug gap? how you been driving it??? pedal to the metal? granny?

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laurentj23

Dude that's even worse than mine. I got 320 miles and it's mostly hwy with auto
S14. What was the rpm on hwy speed. It's like 3k at 70 mph on hwy..it sucks donkey balls!

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rahjah

I haven't checked the timing yet. Thanks for mentioning that. Do you know what stock timing should be set at? Someone told me it was 20 degrees advanced from the factory. Does that sound right? Also I only live 1 1/2 miles from where I work and I don't typicaly drive anywhere else. I normally drive it easy unless I am trying to get into traffick. The car never reaches operating temp by the time that I get to work. Do you think that may have something to do with it?

rahjah

On this last tank, I was down to almost a quarter of a tank of fuel and I had only driven 120 miles. I put 9.3 gallons back in so I averaged around 12.9MPG. I traded my 4runner for this car because of the poor fuel mileage and now I am worse off than I was at first. This is teh gay suck.

laurentj23

I feel ya. At leat you dot have to drive back n forth totaling 300 miles every third day! My z got
A better mileage than my s14!

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waste_of_space

Replace the dizzy cap and rotor if you haven't yet, and the wires as well (that way your whole ignition system is up to par) and fuel filter as well. Basically a full tune up. That should at least help a little if you haven't ever changed any of them/don't know when they last were changed.

Double check your fuel lines for leaks/cracks as well. I had the line going to my fuel filter loose and never really noticed it until I started getting terrible gas mileage.

And yeah 20 degrees is correct base timing for a KA (turbo SR is 15)

DreamN

You may have a leak. I'd check all your fuel related lines/hoses.

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Croustibat

I am doing that kind of fuel usage on e85, when tracked, with a 300+ HP CA18DET . Either your engine is dead, or there is a leak.

laurentj23

How is a dead engine consumed so much fuel? So 320 miles for f to e is bad for an auto 240 as well? I already fixed the leak at the fuel filter hose. I dont smell anymore fuel after i fixed that..

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rahjah

Like I was saying in the first post, the car runs perfect. If the compression was low or inconsistent wouldn't in run poorly? I guess I could do a compression test, I haven't done one yet.

rahjah

I did not drive my car for about four days, the weather was nice and I was riding my bike. I got in the car two days ago to drive to work and it was running like poopie. I figured it was just because it was cold and it hadn't been ran in a few days. As I was driving it seemed to clear up but whe nI came to a stop it stumbled and struggled to run. It was putting out some serious black smoke (I was told that black or brown smoke was fuel, please correct me if this is wrong). I pulled all of the plugs and they were all gas fouled. I replaced them with new NGK plugs and nothing changed. I decided to unplug the MAF and see if the problem persisted, it did not. Once I unplugged the MAF the idle cleared up and there was no smoke. I plugged it back up and the problem instantly came back. I ordered a new (used) MAF that sould arrive today. I will post whether or not this fixes the problem. Thanks again for all if the tips.

laurentj23

Black smoke= bad seals. need to do a compression test ASAP!

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rahjah

Ok, if it is bad seals, why would it clear up when I unplug the MAF? I'm not trying to be a smart ass, I am just trying to figure out how the two could be related.

iveexcaped3

you could have 1 or 2 leaking injectors. if their running all 4 strokes your gonna get shit mileage, always start with cheapest though like mentioned before change the fuel filter if you havent already, and you shoulda cleaned your maf first before buying a new, do you have any CEL?

iveexcaped3

black smoke doesnt always nessisarly mean its seal, ive seen black smoke because of a leaking injector, do a compression test and a cylinder leak down test that will tell you if its seals or any thing like that

rahjah

I did clean the MAF when I first started trying to track down the mileage issues, it did not help. The car was still running fine just getting shit mileage. I did have two injectors leaking into cylinders one and two, fixed that car ran great but still got shit mileage. The new MAF was only $50 so I won't be too heart broken about the money if it doesn't fix the problem, just heart broken about the problem. Also, the check engine light is not on. I believe it is working as it lights up when I turn on the key. Should I still try to pull codes?

Broker Face

if maf is bad shoudnt it throw some codes.
just sit tight until that new maf comes in

iveexcaped3

yes the maf should throw a code, and if you click the key on and it lights up that means the bulbs arent burnt out, whats your idle RPM at? normally when you unplug the maf it should die out cuz the cpu has no reading of how much air is going in.

rahjah

Well, I just took the MAF off of the car. I heard something rattling around inside. I popped it open to have a look and discovered a broken solder joint. I re-seoldered it and that fixed the poor running issue. I am still going to install the replacement when it arrives and hope that helps with the fuel mileage.

sidelight

clean the throttle body well
Clean the maf, once its 80 or hotter outside.

change transmission fluid if 3 years or more. only if know how
change the diff fuid.
New fuel filter if it been 2 years old

With spark plugs, only get single tip, platinum or better.
With double or 4 tip, the spark isn't better.
Over 160k, change them every 8 months for mpg.
1 platinum plug is $3-$5

clean IACV, this takes 2 hours.

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