View Full Version : 140 miles on a tank??

01-06-2002, 10:56 AM
Ok I've got a question for you guys and I hope you can help. I have a stock 90 240sx and i'm only getting 140 to 180 miles on a tank. i'm hoping that this isn't normal

01-06-2002, 11:08 AM
you've definitely got a problem! i get between 300-325 miles if i drive normal. even running 80-85mph on the interstate i get 275 miles.

01-06-2002, 01:31 PM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by quickshift:
Hey SOHCfan. Where in Chas. do you live? I am outside the AFB.<HR></BLOCKQUOTE>

i live in Otranto, near the Super K-Mart

01-06-2002, 01:59 PM
I've got a pretty minor exh leak...cut's my mileage from 300-320 down to about 250-275


01-06-2002, 02:25 PM
I have the same problem too, except I get around 180 to 200 a tank. I have changed within the last 6months:

o2 sensor
reset timing back to factory spec
added k&n
cat back exhaust

Oh and its an automatic sohc with 175K...=P. What do you guys think? Normal?

01-06-2002, 02:46 PM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by geeaj:
I have the same problem too, except I get around 180 to 200 a tank. I have changed within the last 6months:

o2 sensor
reset timing back to factory spec
added k&n
cat back exhaust

Oh and its an automatic sohc with 175K...=P. What do you guys think? Normal?<HR></BLOCKQUOTE>

not even close. how does your car run? idle?
any leaks around the injectors?

01-06-2002, 02:58 PM
No injector leaks, no vacuum or idle issues. It idles at 750rpm in drive and about 800 rpm in Park gear.

You think it could be my IAC or the AIV unit being faulty? I don't think its the cat since I don't have any rotten egg smells.

I do notice however, that after I smash in my car, once I turn off the motor, it has a metallic smell in the air. Kinda like a exhaust after you first get it installed.

It has good power and doesn't burn oil.

01-06-2002, 03:04 PM
Wow, that's pretty bad. On my current tank I'm at 180 miles and the needle's just on the halfway mark. Another as to why you're getting such crappy gas mileage is leaking injectors.

01-06-2002, 03:06 PM
I don't see any leaking gas, nor smell it. I know this for a fact because it just passed smog.

01-06-2002, 03:13 PM
I get approx. 225 miles a tank doing city driving on a pretty much stock 1993 S13 with 125K. It runs extremely well and burns no oil. I thought this was normal, but apparently not. I wonder what could be the problem since it runs just fine. 180 miles at half a tank. Wish I could do that. http://www.freshalloy.com/

01-06-2002, 03:24 PM
JEEZ! this is a freakin epidemic! i gotta go with chris@speed alliance.com, you guys should check for exhaust leaks. i'd start with your exhaust manifold and work back.

01-06-2002, 04:57 PM
I get around 220-230 miles to the tank, so far I've replaced the dist cap/rotor, o2 sensor, plugged the hole from the airbox to the AIV (if thats the one that goes to the exhaust) since the tube wouldn't attatch (the fitting on the secondary resonator for the AIV is fuxored, it broke off and is now attatched to the tube).. I've been running mostly chevron lately, but the cheap stuff..
~120k miles, 89 SOHC (not the hicomp one AFAIK)... I also did my own oilchange with a nissan OEM filter for the first time a few weeks ago.. heh. I have a fuel filter just haven't changed it yet. I am burning and leaking oil both, about a quart every 2 weeks or so. you can smell my exhaust, I'm definately running rich (or have a nonexistant cat - previous owners suspected the one before him had it hollowed out, but it passed emissions for him just fine. we'll find out if I pass emissions later this month http://www.freshalloy.com/ )

edit: Haha, also forgot to mention whenever I pull the plug boot off the 4th cyl sparkplug, oil drips outta the boot http://www.freshalloy.com/

I just need to find a 91 DE or so to replace this dying SOHC with http://www.freshalloy.com/

[ 01-06-2002: Message edited by: BioSehnsucht ]

01-06-2002, 05:27 PM
I too was getting only 150 or so miles a tank in my 89 240sx so last week end i pulled the intake plenum off and replaced the gasket $3.xx at Courtisy Nissan and put new rubber seals in for the injectors... alot of the vac*** hoses started to brake and split so i replaced some of them too... well most of them. Im getting like 350miles to a tank now it was well worth the day of work to get it right. Cjex

01-06-2002, 05:56 PM
1) DOHC owners need to understand that their motors are MUCH more efficient in terms of gas mileage. DOHC owners seriously get 300+ miles to their tank, easy.

2) SOHC owners, if your car is in-spec then your gas light should activate around 240-300 miles. If you drive highway, then for sure you will be hitting 300 or maybe even more if you trickle the throttle.

3) SOHC owners, if your check engine light IS on, like mine, then you WILL get around 200-260 miles to the tank, even less if you drive extremely hard. Right now, I get around 200 miles till my gas light turns on.. thats 14 gallons used. I took a trip to san diego recently and under very light throttle, filled up around 260 WITH check engine light on.

Worse I've ever gotten was around 160-180.. and thats driving like an absolute fukking maniac. http://www.freshalloy.com/

Hope that helps.. I've been observing this one for 6 years now, AND, my motor is in pretty good shape (new gaskets, vacuum lines, etc).

- Mike

01-06-2002, 06:02 PM
WTF 300+ miles on a DOHC? Am i missing something here? I have an '92 Auto with 100K (miles) on it and i get anywhere from 220-250. i just replaced the cat.

01-06-2002, 06:17 PM
well I have a 89 SOHC with about 129K miles on it and I can drive 310+ miles highway on a single tank. City I get about 280+.

01-06-2002, 07:16 PM
My '91 DOHC gets around 300-320 on a tank if i behave and around 220-240 if i fuc around. A buddy's S14 DOHC gets over 400 miles on highway and around 300-320 city driving.
I think if i actually drove on a highway till i was out of gas I'd get around 360 miles.


01-06-2002, 07:55 PM
I think that when some of you say "a full tank" you may not mean the same amount as others. To some, they will never go below a 1/4 tank, but will say they are empty. A 1/4 tank is a lot of miles in my car. If I filled up with a 1/4 tank left, I would get about 220 miles, but when I wait to fill up until it is about as low as it will go, I get well over 300 miles. Best total miles to a tank yet is 380, and that is with 135K miles on my car.

01-06-2002, 09:17 PM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by BioSehnsucht:

edit: Haha, also forgot to mention whenever I pull the plug boot off the 4th cyl sparkplug, oil drips outta the boot http://www.freshalloy.com/

I just need to find a 91 DE or so to replace this dying SOHC with http://www.freshalloy.com/

[ 01-06-2002: Message edited by: BioSehnsucht ]<HR></BLOCKQUOTE>

My bro had that prob a while ago on his 78 chevy malibu. I know its a boat and everything, but dont laugh. It could lay some impressive 1/4mi times. One of the holes on the head were crossthreaded bigtime by the guy he bought it from. It was some heavy-drinking military guy that I hate. He ended up buying a new head for $30 from a junkyard. It's a chevy 350, so all of the parts were really, really, really cheap to replace.


01-06-2002, 09:30 PM
Just for comparison:

On a completely stock setup, I get roughly 26MPG on purely highway driving and anywhere from 19-23 in the city.

On my current setup (JWT ECU/cams, exhaust/intake/header, DPR head/manifold, etc) I get about 29MPG highway and 20MPG city.


I have a '93 KA.

[ 01-07-2002: Message edited by: Mav1178 ]

01-07-2002, 12:05 AM
Hey SOHCfan. Where in Chas. do you live? I am outside the AFB.

01-07-2002, 12:59 AM
Check your O2 sensor first, then start with the basics, plugs, wires, cap, rotor, fuel filter, etc. I run my car hard and get 330 miles average, so you've got a serious problem somewhere.

01-07-2002, 01:59 AM
I've always been blown away with topics like this because city doesnt always mean CITY. And empty doesnt always mean EMPTY. Everyone gets confused.. a big mess!

For us LOS ANGELES folk, CITY MEANS stuck in fukking traffic while playing with your ballz, stoplight to stoplight traffic.

For those of us who accurately monitor their mileage, we wait till around the time gas light turns on and then go fillup. The gas light lets you know that there's about 2 gallons remaining. My S13 carries 15.9-16.5 gallons, cannot remember. With 14 gallons gone, I've reached around 200 miles on the trip meter. Again, this is with my check engine light on and an insano-driver-o. When I didnt have the check engine light on, we're looking at 240 miles/14gallons. This is ALL city, 0 highway. I rarely use highways.

- Mike

01-07-2002, 02:09 AM
I have a turbo auto 97 with the jwt program set to run slightly rich. I get about 17 mpg all city.

Before the turbo I would get 19-21 mpg all city.

If you're getting under 20 mpg with a manual I think you have a problem. For an automatic, I think that's about right.

01-07-2002, 02:10 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by old_s13:
My S13 carries 15.9-16.5 gallons, cannot remember. <HR></BLOCKQUOTE>

All S13's have a capacity of 15.7 gallons.


01-07-2002, 02:12 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by old_s13:
I rarely use highways.<HR></BLOCKQUOTE>

highways in Los Angles is like normal city traffic in other city's... the max speed you get is 35 mph and stop and go every 30 seconds.... man it took me 1hr 25min once to get from east los to torrance on the highway around 1pm on a friday.... there is nothing highway about los angles highways http://www.freshalloy.com/

i know traffic... i grew up in NYC(frik'n cabbies)... man but LA takes the cake.

oh but back to the topic... i get about 450km per tank(aprox 300m) on my sr..... so i would think you may have a slight problem... a dieing injector would be my guess.

01-07-2002, 02:57 AM
By the way, in addition to checking the regular sensor and plugs, make sure your compression is okay on the engine, and that you are firing on all 4 cylinders and that the injectors are opening/closing correctly.


01-07-2002, 05:26 AM
I do usually 3 trips to work and back with my SOCH. 1 trip contain: 20 km city traffic, 40 km highway in 120 km/h and 80 km full gas until speed limiter hits. This is ca 450 km together and I have enough fuel to do half of trip with normal speed. When I drive with normal highway speed, I can travel 4 times with 1 tank. First thing for me is take a good care about air filter.

01-07-2002, 05:58 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by Mav1178:

All S13's have a capacity of 15.7 gallons.


I guess thats about right because i just filled my tank and the light was on. Like old_s13 said, whens the light goes on, theres about 2 gallons. i filled up 13.74 gallons.

01-07-2002, 07:59 AM
My 92 S13 (stock except for K&N cone filter) gets between 19-24 miles per gallon depending on the type of driving I do (highway or backroads). That usually equates to about 275-300 miles before the low level light comes on. BTW, all S13 tanks are 15.9 gallons if anyone hasn't mentioned it already.

01-07-2002, 08:15 AM
out of curiosity, what's the capacity of an s14? how many miles do you s14 people usually get. i normally refill with a little less than 1/4 a tank left, and i get around 240 miles of mostly city driving, but without a lot of stop and go.

[ 01-07-2002: Message edited by: 98SilviaS14 ]

01-07-2002, 08:44 AM
Kind of on topic.. When you first turn your key to start the car and all the lights on the dash go through their self test, does the gas light turn on too? I'm wondering if mine might be burned out since it doesn't self test.

01-07-2002, 10:52 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by 98SilviaS14:
out of curiosity, what's the capacity of an s14? <HR></BLOCKQUOTE>

S14 was 17.5 gallons (or something real close to that) last time I checked.


01-07-2002, 11:26 AM
How about the O2 sensor? Has anyone tried replacing that? I heard it might help with my bad gas mileage I've been getting. Currently I get about 250-270 miles on a tank FULL to CHECK FUEL LIGHT. My car is a SOHC, btw. I think I should be getting far better mileage than this.

Anyone else changed the sensor?

01-07-2002, 11:38 AM
Okay - so who is right? Alex, I have a feeling its 15.9.. anyone?

- Mike

All S13's have a capacity of 15.7 gallons.


<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by Mike 240SX:
BTW, all S13 tanks are 15.9 gallons if anyone hasn't mentioned it already.<HR></BLOCKQUOTE>

01-07-2002, 11:40 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Like old_s13 said, whens the light goes on, theres about 2 gallons. <HR></BLOCKQUOTE>
I can go 10 miles after the light goes on. Appx. 1/2 gallon. Ran out of gas 2nd day of ownership (What a suprise!). Been this way since new.
Anyway, 260 appx. miles per tank in city for '90 SOHC.


01-07-2002, 11:53 AM
From the FSM, it's 15-7/8, which is 15.875 .


<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by old_s13:
Okay - so who is right? Alex, I have a feeling its 15.9.. anyone?

01-07-2002, 03:48 PM
I posted to this earlier, but I'll add more. I have a 96 5 speed, every available bolt-on, no emissions equipment other than a RT catalytic, and drive the piss out of my car. I average 350 miles a tank. I'm seeing that my figures are better than most, does that make sense? I'd guess mine would be worse. Weird.

01-07-2002, 05:04 PM
1) Your car is an S14
2) You live in some OTHER place. Come to LA and tell me you get good gas mileage.. HA! Our gas is all water'ed down.. http://www.freshalloy.com/

<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by R240NA:
I posted to this earlier, but I'll add more. I have a 96 5 speed, every available bolt-on, no emissions equipment other than a RT catalytic, and drive the piss out of my car. I average 350 miles a tank. I'm seeing that my figures are better than most, does that make sense? I'd guess mine would be worse. Weird.<HR></BLOCKQUOTE>

01-07-2002, 06:26 PM
I think the s14 tank holds 16.9 gallons.

01-08-2002, 12:07 AM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by 98SilviaS14:
out of curiosity, what's the capacity of an s14? how many miles do you s14 people usually get. i normally refill with a little less than 1/4 a tank left, and i get around 240 miles of mostly city driving, but without a lot of stop and go.

[ 01-07-2002: Message edited by: 98SilviaS14 ]<HR></BLOCKQUOTE>

well my gas gauge is broken. sits at full for 250 miles then falls to half a tank. most all of my driving is highway. at that point I refill the tank usually about 9-10 gallons. at about 300 miles the gauge drops to just below the 1/4 mark fill ups there usually in that 11-12.5 gallon range. OH and this is a 95 5 speed with intake and exhaust. gonna turn 120,000 tomorrow on the way to work.


01-08-2002, 10:22 AM
it all depends on how/where you drive. it can be a huge difference. in the city, i get 400km per tank, on purely highway I get over 500km.

10-14-2002, 03:10 PM
I'm new to the boards and I drive a 90 240sx auto with 78k on the engine which has geat power but it only gets 200 miles per gas full of tank if I'm lucky. what is wrong? when I bought the car I had to replace the exhaust manifold gaskets and a leaking fuel filter, is there anything else I should replace if the fuel filter was clogged?

10-14-2002, 03:30 PM
I don't understand people using the gas light to figure out how much fuel they have left..

To check gas mileage you should reset trip meter, fill up, then use about all of the tank, then fill up and see how many gallons it takes and divide that into how many miles your trip meter shows. The gas light is based on a sensor that probably isn't meant to be very precise.

10-14-2002, 03:50 PM
My gas light doesnt even work so I just ride it until its on E most of the time.

Are there any ways I can check the fuel injectors myself? I dont see any leaks of smell any gas.

10-14-2002, 04:00 PM
I havent actually figured my mileage, but I do know it takes about 3/4 of a tank to drive from Tulsa to Dallas, which is about 250 miles. I estimate about 330 miles on a full tank. By the way, I have a '93 Coupe with 126k miles.

10-14-2002, 05:31 PM
Try not to run the tank down too far. The bottom of fuel tanks is often where particles and other sediments rest. Running it to near empty just ends up sucking up a lot of that crud which will subsequently clog your fuel filter quicker.

For the record (wow old post revived) I get 270 miles per ~14 gallons on an S13 SR20DET running 9psi of boost.

10-14-2002, 06:57 PM
Can anyone give me any ideas as to why my gas milage is so bad? The car had a tune up done on it before I bought it. How would I check my injectors for leaks?

I get 200 miles per 15.9 gas tank on my stock Ka24e

The car runs great just doesnt get good gas milage.

10-14-2002, 07:44 PM
I drive an 89 S13 with a redtop SR at .60 bar (about 9.0 psi) stock injectors, 255 intank pump. On the way to NOPI, in probably 90% highway driving at 140-160kmh most of the way, I got 506km in a tank. The low fuel light just popped on when I pulled off to a Texaco just outside ATL (Conyers, GA?)

That works out to 316 miles or so. I still think that I may have an injector with an irregular spray or something. They do not leak, I've checked that. But I still hit 1600 on my HKS egt (probe mounted in the collector of the stock manifold). This is at stock boost too.. how are others running 1 bar safely on their 370s? http://forums.freshalloy.com/ubbthreads/images/icons/confused.gif

And if I do have an injector problem, how is the mileage still so good? http://forums.freshalloy.com/ubbthreads/images/icons/confused.gif

10-14-2002, 08:01 PM
I wanted to add that I made a quick round trip to MD this weekend for a family thing. I live in Myrtle Beach, SC.

The car ran flawlessly.. cruised effortlessly on the highway all day at 140kmh (about 88mph) and some bursts to 160-180. I made the 530 mile trip in a tank and a 1/4. On the return trip, I left Hagerstown, MD and finally stopped (no fuel light even on) in Selma, NC which is about 50 miles past my normal gas stop of Rocky Mount, NC in my GF's Civic we usually take. I have to look on a trip calcualtor to check the mileage covered.

I still need to do a lot of tuning on my SAFC, especially on the low throttle map for better driveability/economy. I pulled some of the gas out of the midrange at low throttle and I think this contributed a little. My EGTs cruising at about 140kmh were about 1200-1300F on average. I have a Nismo 1.6mm headgasket that drops the compression so I can hypothetically run it a little leaner and still maintain a margin of safety and open the window to some more power (I hope).

I think I have a MAF problem now too... car is now bucking as soon as it comes into boost in 1st and 2nd, and always at about 4500rpm...No boost leaks. Good thing I have a Z32 on the way from friends in Japan..


10-14-2002, 08:20 PM
</font><blockquote><font class="small[/img]In reply to:</font><hr />
I think the s14 tank holds 16.9 gallons.


Nope - it is in the 17 gallon range like Alex said.

10-14-2002, 11:06 PM
From my experience I get ~400km from full to the warning light. Its a 90 sohc, rebuilt. Took out the aiv unit, pluged the hole. I suspect leaking injectros because I run rich and get bad milage. So I disconected the vacum line going to the fuel pressure regulator. Much better milage, better power.

As far as the reserve on the fuel. After the light goes on I can easily do 80km. So go figure our cars are messed up.


10-14-2002, 11:37 PM
Your injectors are bad/leaking
im sure of it. I had the same symptoms until i replaced the injectors one by one. TWO of mine were leaking.

10-15-2002, 12:54 AM
I checked the injectors and they are all clicking I dont know enough to safely remove the injectors and install new o-rings.

My gas warning light doesnt work @ all even during the self test. What could be the problem there?

10-15-2002, 01:41 AM
Im sure its not your rings that its the actual injectors them selves. U will smell the fuel if it were bad rings.
I picked up a used set of "good" injectors and one of the "good" ones was actually leaking.

Its fairly easy to replace them. There are two 12mm bolts that hold on the fuel rail. Thats all u need to take off.
When the bolts are off lift off the fuel rail and it will move far enough away to take out each injector. There are two o-rings that should be replaced while your in there. One is on the top of the injector and the other sits in the intake manifold. Sometimes the o-ring that sits in the manifold will come off with the injector itself.

Correct me if im wrong but thats how i did the injectors on my sohc 240

10-15-2002, 02:16 AM
Where would I take my injectors to get checked out?

thnx foe your help.

10-15-2002, 03:19 AM
there is no need to check them out there is a way but yyour saying that your not mechanicly inclined then its easier to replace than to trouble shoot.
they are probably bad and are not worth to check out.
i picked up the injectors for 40 bucks for all 4.

worse comes to worse u could have a mechanic do the injectors for probably around 35 dollars.

10-15-2002, 10:48 AM
I'm just going to throw this idea in and see what happens http://forums.freshalloy.com/ubbthreads/images/icons/grin.gif

Do any of you guys regularly CHECK YOUR TIRE PRESSURE http://forums.freshalloy.com/ubbthreads/images/icons/confused.gif
(tire pressure has not been mentioned at all http://forums.freshalloy.com/ubbthreads/images/icons/blush.gif )

10-15-2002, 12:26 PM
I don't think that there is any way that the tire pressure could be off enough to give someone less that 10mpg. Tire pressure could account for a difference of 3 or 4 mpg AT THE MOST.


10-15-2002, 01:05 PM
Just to end the confusion, the S14 holds 17.2 gallons. I've never gotten it close though, because my light comes on with around 3 gallons left.

10-15-2002, 02:38 PM
I just had new tires installed.

10-15-2002, 03:04 PM
I thought my 89 XE with an auotmatic got bad mileage at 24 mpg, but that is awful. My 89 has 180,000 miles. I tuned it up once and did not replace the O2 sensor until a week later. I took a road trip at about 65 mph for many miles and got 34 mpg. I then got 29 mpg on the next tank and from then on though I keep getting about 24 mpg. I wondered why it was so good and then got worse. I think it might be Bosch O2 sensors suck. BTW, the 89 is all stock.

I also have a 92 base model coupe with a manual. With a real heavy foot I still get 26 mpg or better. I get 29 mpg on average and I get about 32 mpg at 75 mph on the highway. I often go over 400 miles on a tank in this car. All I have on this car is iridium plugs and I don't use the bottom half of the air filter box with a replacement K&amp;N filter. The 92 has 125,000 miles.

Where can I get injectors (good) for a KA24E for $40?

I noticed Alex gets better mileage with a JWT ECU. Alex, does JWT retune ECUs for stock KA24DEs that will give me better mileage and what would it cost? Also if JWT does do that what would it cost to get it retuned later for turbocharging?

10-15-2002, 03:17 PM
Oh yeah, I forgot. I do all this driving on 87 octane gas. I can get close to 40 mpg on 93 octane on the highway at 65mph with my 92 coupe.
I think I will try what vortex240 did with his AIV and fuel pressure regulator. My 89 definitely runs rich. You can smell the eggs sometimes.

10-15-2002, 06:16 PM
just for the info since some were curious about the s14, i have a 5spd and get about 360-390 consistently on my car, depending on how i drive. i do a nice mixture of about 40% city and maybe 60% highway here in san diego (dunno how that compares to some other cities) so i figure purely highway i can get it well over 400 on a full tank.

gas light usually comes on around 330-350 and i drive till around 370-390 and just fill up. i normally monitor how many gallons i use when i refill and usually there's about ~1.5-1.0 gallon left. if i'm driving like a maniac it'll come on at 300-310 and i just go 30 miles and refill. so by my calculations i'm getting about 23-25 mpg with almost 50/50 city/highway driving on about 15 to 16 gallons in San Diego. hope that sheds some light on this.

edit: oh yeah, this is on 91 octane with injen CAI and apexi dual n1's. my mileage got a lot better after i put on the cat-back exhaust.

10-15-2002, 06:22 PM
I have an FSM and I have tried everything. The engine is rebuilt. New: O2, fuel filter, air filter, distributor, wires, plugs, exhaust. Checked: MAF, timming, egr...probably a lot more. Also 1 new injector(it just died).

To lean it out. A LOT - just disconect the O2 sensor wire.

A little - disconect the fuel pressure vacum hose. It works for me and my friend's sohc but I can't guarantee it will work in anybody elses car.


10-15-2002, 07:05 PM
What is an AIV, I'm not too up on the terms.

10-15-2002, 07:36 PM
Air Induction Valve routes air from the intake into the exhaust flow. It is the little black box located on the driver side near the exhaust manifold that connects to both the intake tubing and the exhaust.


10-15-2002, 09:41 PM
I just purchased an 89' SOHC S13 this morning, filling up the then empty tank with 89 octane. I then installed my stereo (very basic, nothing fancy), and fixed two of the burnt tail lights. I did my daily driving and errands in it, just to get acclimated (former Z32 owner) to the lighter weight and such. By the time i had made it home this evening, my indicator stated exactly 1/2 a tank, but i only had 72 miles on the trip odometer. Thats an awful lot lower than i had expected when i purchased the car.

Poked around under the hood, and found a pretty heavily trashed air filter. I replaced it with a new one from a local shop (this was maybe an hour ago) and then drove a bit to see where things stood. The idle was still rough (starts at 2k RPM during ignition, then very slowly down to 1500, pauses, then down to 1000, pauses, then 900, then just bounces between 500 and 900 until i begin to drive). At highway speeds around 60-65, theres a definate "throttle-strobing" effect, where it seems to rev, then drop, then rev, then drop again. Very unsettling.

I bought it from ZCar Atlanta this morning (same guys who did all the Z work i couldn't do myself) and am still seriously impressed with the overall condition of the car. I know it sat on their lot for a good two or three weeks, but after gently starting it and letting it (try) to idle, i began to drive it. I'm now just about out of gas, with a pretty bad idle, on an otherwise mint 240sx coupe with only 89k miles.

Ideas? Concerns? People wanting to meed up and junkyard dive for parts or help me diagnose? Anyone at all? : )

10-15-2002, 10:56 PM
Sounds like a leak in the intake piping after the MAF, or a bad MAF. Also check for ecu codes.


10-16-2002, 12:11 AM
Also look at the fuel injectors. Early 240s are infamous for having leaky injectors and/or seals. Do you smell any gas when you start the car? Notice any of the signs of leaks around the intake manifold?

Oh, and I forgot to mention, run out and get a new fuel filter out of a Z32TT, it could be contributing to your problems but I doubt the only cause.


10-16-2002, 04:07 AM
I went by a shop today and they told me that they'd charge me $95 to test my fuel injectors and would charge me between $100-$150 to install new injectors depending on the color of the injectors.

Should I pay the $95 or just order new injectors @ 65 each and find somewhere cheaper to install them.

10-16-2002, 04:09 PM
How would disconnecting the O2 sensor lean it? The sensor is supposed to be around 1 volt when it is rich and near 0 volts when it is lean. It seems like disconnecting the sensor would constantly send a signal of 0 volts to the ECU making it think the car is running lean thus enriching it more.

The need of a tune up, low tire pressure, bad fan clutch, bad alignment, and bad struts combined can really drive your mileage down. I had a combination of all these things when I bought the 89 but I still got over 20 mpg.

10-16-2002, 05:36 PM
If you have the green, go out and get new injectors and o-rings, etc. and then install them yourself. It is not hard, and requires only basic tools and knowledge. I would try and find someone in your area and have them give you a hand. I think you will find that being able to get it done by yourself you will learn and save some money. Asad recently posted the procedure if you can't find anyone in your area. Search by his screen name.


10-16-2002, 11:00 PM
The ecu has its base program and fuel maps, wchich it only adjusts. So say it is getting 0V so it thinks everything is going well = no need to adjust the base fuel map for the amount of air that MAF reads.


10-18-2002, 01:38 AM
Can the fuel injectors be bad if I cant see any sign of leaks on the intake manifold?

I just looked today and they dont look bad.

10-18-2002, 03:29 AM
Yeah, you can't really tell. They don't rust or crack or anything. Its the inside of it that stops working properly.


10-19-2002, 10:53 AM
thats way weird my 98 nissan gets like approx 325m+ on a (11-11.5) gallon fillup. Something definitely is up on your engine http://forums.freshalloy.com/ubbthreads/images/icons/crazy.gif

02-23-2003, 07:45 AM
Thread Revival!!

I've replaced my fuel injectors and the eletrical connectors but still get ****ty mileage I may need to change my o2 sensor and spark plug wires, I've changd the plgs but not the wires or the cap and rotor would changing those things really bring my gas mileage backup?
My trip meter is currently on 89 miles and the needle is @ half a tank so I'll be lucky to get more than 200 for my whole tank.

02-23-2003, 08:15 AM
good god man, this post has been over a year old! glad your narrowing the problems down.

02-23-2003, 06:27 PM
Damn you guys are having some trouble! I get over 350 pretty damn often. Best mpg I've seen is 30.5, usually get 26 around town.

02-23-2003, 10:29 PM
Hey, I am there too! [censored] for gas mileage on a stock 89 s13 ka24e. All new ignition components and o2 sensor. Had a garage scan the system without any results. For the record the card is supposed to get pretty poor mpg anyway (24mpg highway EPA) but I am wishing I could get this. I am lucky if I get 300 miles on a tank even on highway driving. The car runs great though. Can I have leaky injectors without the garage being able to detect it? The gas mileage is too poor to attribute to tire pressure or driving style. I have logged 100s of thousands of miles on all types of cars and always get EPA rated mileage on good running cars. (+/- 2mpg)

02-24-2003, 04:10 AM
right now I'm trying to just get 200 mile for my whole tank.

02-24-2003, 06:42 AM
LOL!.. this is hilarious.. I wonder if it is something about the 24E's.. before mine took a $hit on me I was getting about 120-30 per half tank.. course I drove the piss out of it.. but still..hehe.. hope you find the problem.

02-24-2003, 12:12 PM
Just wondering the guys that are supposedly getting 300+ on a tank of gas what tire sizes are they running?

02-24-2003, 12:16 PM
I'm running stock tires (195/60/15) on a J30 rear end. I multiply the mileage I get by 1.04

Sometimes when feeling silly I multiply by 1.0437215. Yup!

02-24-2003, 12:21 PM
I get roughly 500 km per tank (like 310 miles) in the summer/spring and about 400-450 in the winter.


02-24-2003, 12:28 PM
i get between 300 - 350KM per tank on a 93 redtop sr if i drive normal note this is km not miles http://forums.freshalloy.com/images/graemlins/crazy.gif

02-24-2003, 01:20 PM
Just wondering the guys that are supposedly getting 300+ on a tank of gas what tire sizes are they running?

At the time when I recorded my 30mpg tank, I was running 215-50-16 -- about 1% larger. It came out to around 400 miles as indicated on my trip odometer (and I doubt the odometer is accurate to 1% to begin with).


03-06-2003, 08:33 PM
ok update, I just changed my o2 sensor and it was coated black, so in the past few months, I've change fuel injectors and electrical connectors, fuel filter, o2 sensor, any other ideas to better my gas mileage.

I gotta see what I get since I just changed the o2 sensor.

03-06-2003, 09:27 PM
Before I pulled it apart, I was getting ~20mpg driving it like I stole it, about 50/50 city/hwy. Mine's a 89 SOHC, low compression motor.

What I've learned since then: cylinder compression is a tad low on all cylinders, and much lower on cyl 4 (I forgot what, but its like 140s or something instead of 170s ? it was pretty low). When I sent my stock injectors to RC Engineering (it was ~$120 to test/clean/test and mail back mine) I got a report card back stating 1/2/4 were all 'bad' spray pattern and 3 was leaking. (after, they are all 'good'.)

I had removed the Y pipe, other than that I had no real mods of any sort. It already idle'd high, around 1200 cold and 900 warm (manual).

It dyno'd, despite all this, at ~110whp and ~120ft/lbs.. I don't have the dyno in front of me (at work) so I don't recall the exact #'s.

Sadly I have not yet got it together again but will have the cleaned / improved injectors, Injen intake + CAE (maybe - gonna try it both ways) + JWT POP charger (clone, I think, off ebay.. 1/2 retail and didn't appear to be real JWT and the filter didn't say K&amp;N but it same type), HKS Sport exhaust, new hi flow cat (still need to purchase that one), Hotshot header, UDP.. new plugs, wires, PCV, Z32 fuel filter as well.. so hopefully this will all improve http://forums.freshalloy.com/images/graemlins/smile.gif

I'm also replacing all my vacuum hoses &amp; etc.

CJex here in Dallas (Garland) bought a $300 auto 89 that was getting like 11mpg, replaced all the hoses &amp; other misc and got it up to like 20 or so I don't recall.. that and he rebuilt the tranny himself http://forums.freshalloy.com/images/graemlins/smile.gif

So don't forget to replace old/broken vacuum hoses.. and PCV valve.. and other maintenance items.

(Sadly, its been more than a year since I took apart the 240.. its been up on jackstands for close to that time.. haven't had a chance to put it back together what with work, weather, every other car we own breaking, etc -- however hopefully next week I can get it mostly if not totally back together again.. shouldn't take long, I've got all the gaskets &amp; etc I need..)

03-06-2003, 11:20 PM
500 miles today...

My headgasket isn't looking so hot in between 2&amp;3 (that or rings, but the coolant turning to foam tells me headgasket) and the car feels a little down on power. Mileage dropped to 24mpg, but the tank I'm on right now looks like a 28, so I'm hoping...

03-07-2003, 01:10 AM
Right now(winter, -30 degrees Celsius) I get 8.9km/L (20.9mpg). This is with a lot of use of the car starter. In summer, I get about 10.6km/L (25mpg).

This is all city driving with a 98 S14 w/ intake/exhaust.

03-10-2003, 04:31 AM
I've changed my o2 sensor which was coated black from running too rich due to leaky injectors and and the electrical connetor clips missing.

Air Filter, Fuel Filter, Injectors, Electrical Connectors for Fuel Injectors and o2 sensor all changed.

We shall see what my gas mileage looks like soon

03-10-2003, 04:33 AM
what's it mean if your o2 sensor has white spots all over it?

03-10-2003, 04:48 AM
but the tank I'm on right now looks like a 28, so I'm hoping...

I was right, hit 29 on that tank.

Hit 25 on the second tank. 1000 miles on my car this weekend, just about 3 tanks of gas. 23, 29, 25. Not too bad, all pretty much cruising at 80.

Car gets about 200 mpg of coolant...not good.

03-14-2003, 09:25 PM
I'm about to give up on 240sx and jump to a honda, my car is averaging 14 mpg and I've changed everthing fuel related and the mileage still sucks.

Anyone got an ideas, my idle is bad, it jumps around in Drive @ idle.

03-15-2003, 05:23 AM
maybe ur iacv?