fuel economy sucks on my stock single cam KA, any help?

[RedSiBaron]

KA24E ENGINE IS STOCK, has NON OILED cone filter (not killing my maf), and stock header, with an oem diameter muffler shop special exhaust

questions:
1) what kind of fuel economy should i be getting on my single cam ka in an s13?

so i know it doesnt help saying "im not 100% what my fuel economy is" but the trip/odo on my cluster works intermittently, so i cant get a distance traveled per gallons filled to get an estimate

that said i know its not running right, and the fuel economy is not great

2) what should i look at replacing, adjusting, check, to get my engine running efficiently

the engine DID burn a bit of oil when i got it, found it was just hard valve seals, but ive been running valvoline max life, and its softened them up, and it doesnt burn much anymore. i also check the plugs once a week and they arent covered in oil anymore.

i have replaced the fuel filter, pcv, and plugs.

i also obtained a stock exhaust which i will be putting on, after finding a lower stock header section that ISNT welded to a shitty aftermarket cat, and i will not be running a cat.

3) would a bad o2 throw a code on this old car because im not throwing a code. would a bad o2 toast my fuel economy?

4) can i get my injectors re-calibrated and cleaned? is that a common cause for poor fuel economy on this motor?


i searched, and couldnt really find the info i was looking for, or i just suck at searching. so sorry if im being a dumb shit

I am about to start a new job with a 80mile daily commute, and if i could get my fuel economy up a bit it would save me a ton of cash since the 240 is my daily. I dont want to sell the car to save gas, i do love the car.

thanks all

[bb4_96]

how bad is it?

[RedSiBaron]

how bad is it?

Wow, you read well...

Since I can't get solid info, because my odo/trip doesn't really work, I don't know for sure.

closest I can estimate is between 20 and 23mpg depending on how I drive it, but I typically don't beat on it or anything...plus the idea of beating on a lackluster stock single cam is a laughable idea.

[iLagX]

its a 2.4 liter the best way is to replace your diff with a s15 hlsd with lower gear ratio so your RPm will be low but poor low end power.

[RedSiBaron]

its a 2.4 liter the best way is to replace your diff with a s15 hlsd with lower gear ratio so your RPm will be low but poor low end power.

Im not buying that, my fathers 5.7l v8 in his truck gets the same fuel economy. And my friend gets 26+ in his 2.4l swapped civic making 240whp n/a. Displacement has nothing to do with it. Its tuning and gearing. Granted I understand the different rear diff would help. Im not looking to spend big money on the car, im trying to make it work well stock for right now, not looking to play with gearing.

[ZenkiKid]

closest I can estimate is between 20 and 23mpg depending on how I drive it, but I typically don't beat on it or anything...plus the idea of beating on a lackluster stock single cam is a laughable idea.

That sounds about right for a KA.

These engines get shitty gas mileage.

[RedSiBaron]

That sounds about right for a KA.

These engines get shitty gas mileage.

The epa estimates are dead on what im getting and this motor is beat, im convinced im missing something because ive never driven a car I couldn't get 5-10mpg more than the conservative modern epa estimates.

Let's just say hypothetically I am right and I could get better fuel economy than I am getting.

Other than what I've done to tune it up already, what can I replace/fix/tune up that would effect fuel economy, that I havnt yet done.

[rcdad123]

there are a few things you can do to get better fuel mileage. get lighter wheels and tires, puny or restrictive exhaust and intake, new oxygen sensor, drive like a grandma, stay with the speed limit, shift at low rpms, don`t accelerate hard, try not to use the brakes too much, make the car lighter, don`t use the a/c, make sure the engine gets up to manufacturer specified operating temperature, use thin synthetic oil/gear lube. and others may not agree on this but it works for me, is use 91 octane fuel. good luck.

[RedSiBaron]

there are a few things you can do to get better fuel mileage. get lighter wheels and tires, puny or restrictive exhaust and intake, new oxygen sensor, drive like a grandma, stay with the speed limit, shift at low rpms, don`t accelerate hard, try not to use the brakes too much, make the car lighter, don`t use the a/c, make sure the engine gets up to manufacturer specified operating temperature, use thin synthetic oil/gear lube. and others may not agree on this but it works for me, is use 91 octane fuel. good luck.

Thank you for the first useful post. And plus you just gave me an excuse to buy wheels for the car hahaha. I will agree with you, I timed the car for 91 not only does the car run better, it does get better fuel economy, it was much worse before. It ironically also runs better on 87 than when it was timed for 87, though I run it on 91.

What weight gear oil would you suggest for trans and for the diff?

So if I get this stock exhaust on the car, and replace the o2 I should see some improvements? What should I do with the egr ports on the header? I've read I should plug the lower bung, what's the purpose of that?

[rcdad123]

i have an 89 and all of my emissions equipment are hooked up. except for my the egr valve vacuum source. i unhooked it and capped the hose with a golfball tee. i did that so that the egr won`t open(i just passed smog 2 weeks ago with it hooked up of course). the reason why i don`t want the egr to open is so that it won`t clogged the egr passages in the head and intake manifold. i would keep the egr pipe in. that way you would not lose it and look for it when smog inspection is needed and you would not have to make a plug for the hole in the exhaust manifold. as for the oil, i run synthetic 5w30 in my engine and 75w85 in my trans and diff. also my tires are inflated to 38 psi all around.

[RedSiBaron]

i have an 89 and all of my emissions equipment are hooked up. except for my the egr valve vacuum source. i unhooked it and capped the hose with a golfball tee. i did that so that the egr won`t open(i just passed smog 2 weeks ago with it hooked up of course). the reason why i don`t want the egr to open is so that it won`t clogged the egr passages in the head and intake manifold. i would keep the egr pipe in. that way you would not lose it and look for it when smog inspection is needed and you would not have to make a plug for the hole in the exhaust manifold. as for the oil, i run synthetic 5w30 in my engine and 75w85 in my trans and diff. also my tires are inflated to 38 psi all around.

i dont care about smog, we dont have it here in ohio. im ditching my cat all together.

so i want to cap the lower egr?

[zerodameaon]

Change your ECU temp sensor. That will kill your MPG fast. The ecu thinks the cars cold and dumps fuel like crazy. You think the sensors fine cuz the gauge cluster temps look good but they are separate sensors. Also you may need to face the fact that KAs are horrible for gas mileage. Truth and no way around it.
Stock single cam 1989 with a 5spd.
0SX (http://fueleconomydb.com/specs/1989/NISSAN/240SX) City 17 mpg (13.8 litres/100km) Hwy 24 mpg (9.8 litres/100km) Combined 20 mpg (11.8 litres/100km) Yearly Fuel Cost $620 (http://fueleconomydb.com/specs/1989/NISSAN/240SX)

[RedSiBaron]

Change your ECU temp sensor. That will kill your MPG fast. The ecu thinks the cars cold and dumps fuel like crazy. You think the sensors fine cuz the gauge cluster temps look good but they are separate sensors. Also you may need to face the fact that KAs are horrible for gas mileage. Truth and no way around it.
Stock single cam 1989 with a 5spd.
0SX (http://fueleconomydb.com/specs/1989/NISSAN/240SX) City 17 mpg (13.8 litres/100km) Hwy 24 mpg (9.8 litres/100km) Combined 20 mpg (11.8 litres/100km) Yearly Fuel Cost $620 (http://fueleconomydb.com/specs/1989/NISSAN/240SX)

Thanks good info on the temp sensor.

As for the epa estimates, those are manipulated by the epa and are typically much lower than actual real world numbers, and most older car estimates were lowered right before cash for clunkers in an attempt to qualify more older cars to be taken off the road and encourage people to buy new cars. I calculated it last night, im getting 20mpg on the highway. That is trash, I've spoken to other s13 owners who have gotten 30mpg out of their kas on the highway. Id be happy with 25...you know, what they are supposed to get.

[zerodameaon]

I'm just saying don't expect great gas mileage out of a 20to car that wasn't designed with fuel efficiency in mind unless you completely rebuild her. But give the ECT a try. if it doesn't help it was only a 20 dollar part that most likely needs to be replaced anyways.

[RedSiBaron]

I'm just saying don't expect great gas mileage out of a 20to car that wasn't designed with fuel efficiency in mind unless you completely rebuild her. But give the ECT a try. if it doesn't help it was only a 20 dollar part that most likely needs to be replaced anyways.

oh i understand, thats why im not saying i want GOOD fuel economy, i just want BETTER, because i know it can do better. Im really thinking between the ECT and the O2 sensor, and possibly having the injectors recalibrated/cleaned ill see some improvements. again i appreciate the information.

[Jonnie Fraz]

What is your estimate on mileage of the motor? I did read that the ODO is intermittent, but I started to lose compression about 150K. The motor pulled hard and ran great, but would not pass smog. After changing a bunch of parts it turned out it was dropping compression. This could lead to your bad economy if yous is starting to lose some of its gusto.
Just a thought.
Also yes you can have your injectors rebuilt. I did it ran better, a lot better, but would still not pass.

[RedSiBaron]

What is your estimate on mileage of the motor? I did read that the ODO is intermittent, but I started to lose compression about 150K. The motor pulled hard and ran great, but would not pass smog. After changing a bunch of parts it turned out it was dropping compression. This could lead to your bad economy if yous is starting to lose some of its gusto.
Just a thought.
Also yes you can have your injectors rebuilt. I did it ran better, a lot better, but would still not pass.

Well if the motor were original (I don't know if it is) it would have 165k on it. I know about 10k ago he previous owner had the head rebuilt. In any case, that's something ill check and address after I get the exhaust and the header dealt with, but if its losing compression, its in the head, not the rings. I may want to pull the head and replace the valve seals...or maybe ill just find another head and port match it and do a valve job :D

Thanks for the info on the injectors though. I may make a quick trip up the road to this injector shop today and see if and how they do it. Make sure they are measuring cc spray, pulse length, and that they aren't just cleaning them.

Thank god I don't have to pass smog here anymore.

[zerodameaon]

Any updates?
I take back my previous post about fuel Econ. just did a 500Michael drive and I got 27mpg.... but that's after I changed my ECT and put in a manual. ECT had to be the big one though.

[mike[pistonless]]

the car is 20+ years old that gass milage is rather good, you cant compare it to something new

[RedSiBaron]

Any updates?
I take back my previous post about fuel Econ. just did a 500Michael drive and I got 27mpg.... but that's after I changed my ECT and put in a manual. ECT had to be the big one though.

Awesome to hear, I havnt had a chance to work on the car. I have a new job starting monday, so I have been dealing with stuff before that. After I move into my new place ill fix my mpgs

;4185751']the car is 20+ years old that gass milage is rather good, you cant compare it to something new

Read the whole thread before you post...Ive had multiple old hondas that were older than 20years, that still got the same mpg as new at 200k+ and 365k...soooo either nissans are built like shit, or this is a bullshit excuse.

Oh and based on what everyone else is saying, no 20mpg is not good on the highway, even for a 20yr old car...

[Chaluska]

there are a few things that can cause bad gas mileage.

-running no thermostat, makes the engine run rich, because its cold
-old/worn O2 sensor (if you havent replaced it in 2+ years, replace it)
-spark plugs
-plug wires
-weak ignition coil
-the SOHC tranny revs much higher than the DOHC tranny, that can cause worse gas mileage by revving higher at the same speed.
-bad knock sensor causing massive timing pull
-carbon build up in the cylinder walls, causing inefficient burn.

do a hell of a tune up, replace the 20 yr old knock sensor, get new BGK BK5RE-11 plugs, NGK wires, OEM dizzy cap and rotor, get a MSD blaster SS coil (bolts right in to the stock position) run seafoam through the vaccum system, seafoam through the engine, and through the gas tank.. replace the o2 sensor, do an oil change, then feed the car premium. check the timing, and check cam timing, its possible to jump a tooth if the car ran low on oil, and the tensioner looses oil pressure.

thats what i would do.

[RedSiBaron]

there are a few things that can cause bad gas mileage.

-running no thermostat, makes the engine run rich, because its cold
-old/worn O2 sensor (if you havent replaced it in 2+ years, replace it)
-spark plugs
-plug wires
-weak ignition coil
-the SOHC tranny revs much higher than the DOHC tranny, that can cause worse gas mileage by revving higher at the same speed.
-bad knock sensor causing massive timing pull
-carbon build up in the cylinder walls, causing inefficient burn.

do a hell of a tune up, replace the 20 yr old knock sensor, get new BGK BK5RE-11 plugs, NGK wires, OEM dizzy cap and rotor, get a MSD blaster SS coil (bolts right in to the stock position) run seafoam through the vaccum system, seafoam through the engine, and through the gas tank.. replace the o2 sensor, do an oil change, then feed the car premium. check the timing, and check cam timing, its possible to jump a tooth if the car ran low on oil, and the tensioner looses oil pressure.

thats what i would do.

wow thats wicked helpful...thanks a lot!!

question on the sohc tranny vs the dohc...what rpm will the engine be at 70mph? i replaced my tranny with another tranny. the owner had a sohc car but this was the spare trans that came with it and i bought it off him, so i dont know what it came out of.

[Chaluska]

wow thats wicked helpful...thanks a lot!!

question on the sohc tranny vs the dohc...what rpm will the engine be at 70mph? i replaced my tranny with another tranny. the owner had a sohc car but this was the spare trans that came with it and i bought it off him, so i dont know what it came out of.

with a SOHC tranny, at 70 mph, you will be at aroud 3500 rpms, while in a dohc, you will be around 3100

[RedSiBaron]

with a SOHC tranny, at 70 mph, you will be at aroud 3500 rpms, while in a dohc, you will be around 3100

awesome, thanks for the info...my issue right now is that i dont know what rpm everything is actually running at because my tach sometimes reads wrong or maybe its right, i dont know. sometimes it reads about 3k at 70, other times it reads like 4k...i have no idea what tranny i have...ahhh well