Another S13 owner with idle problems...
 

Ive done a fair share of searching and work on my car and still no fix.

I own a 91 240sx Hatch, ka24de motor. After the motor is warmed up the idle starts fluctuating bad....it gets to the point where it eventually dies out. There are even times where if I drop the clutch the rpm sinks down to where it almost stalls out(couple of times it has stalled).

The most logical thing was to take out the iacv and clean it out. Didnt fix the problem. So I decided to go all out and do a complete intake manifold overhaul. I took out the manifold and cleaned it up, replaced the iavc again, cleaned the throttle body, replaced all gaskets, and did a complete vacuum line swap with high grade silicone lines, and added a ground kit.

I now have no vacuum leaks (yes all the lines are in the correct places), I have a clean iacv and intake manifold with all new gaskets, and the problem is still there.

The check engine light has come on and the code its throwing is 55.....as far as I know code 55 means all circuits are good. I dont know what else to do, its pretty depressing to do all this work and dump all this money and not fix the problem. The only other thing I can think of is replacing the o2 sensor.

I could use some advice from you guys.....thanks

willing to bet its your mafs...

take it out and clean it. THey sell mafs cleaners in a spray can at the auto store.

also, you can try this out...

when the rpm starts fluctuating again... pull over (unless you're already pulled over), while your motor is still running, pop the hood, remove the mafs clip then unplug the mafs. I bet your idle might go back to normal. I wouldn't recommend driving like this (if even possible), but at least you'd know its mafs that causing this

Forgot about that one, I have a spare maf so ill swap it over and see if it makes a difference, gonna go to the store and buy a o2 sensor too. Any more advice would be great.....thanks

i have this exact problem as well on my sr.. the car jumps around from like 1000-1600 rpms and keeps going for like 30 seconds then finally settles.. my car died 3 different times on me today at stop lights.... also my car was hesitating at like 2500 rpms when given a little bit of throttle.. like it would start pulling then hesitate for s split second... ill check the mafs for the idle problem but idk wat to do about the sputterness.. i was gonna make a new thread until i saw this so i just wanted to post here

**update** I swapped out the maf with my spare one, the previous one in there was very dirty on the inside. Tried to drive it around to see if it made a difference, but the car started to overheat due to a coolant leak. Soon as I fix that ill test drive the car again and see if the maf was the problem.

I had prior problems similar to what you are having with engine code 45 (leaky injector). Injector #3 was shorting out for me, I had to replace the clip and injector to fix it. If your car feels weaker its possible you are running on 3 cylinders. Best way to test it is let your car run on idle and unplug each injector then plug back in one by one. If the engine responds to the unplug then the injector is working, if you unplug one and there is no change in the way the motor reacts then its possible you have a bad injector. Hope this helps.

there are a lot of things that could cause this, ie. maf, o2, cap/rotor, etc. my problem was a leaking egr valve. so it can be many things. try everything until it goes away...sometimes the egr valve gets worn or really clogged up with sh** and it doesnt work properly

gluck...keep us posted :)

i have the same problem but mine idles under 1000 and fluctuates until it finally dies. much help needed!! bump this thread!!!

**update** ok after fixing my coolant leak i was able to drive the car around after swapping out mafs, drove it around the neighborhood for a good 5 min, parked it back in the garage, let it idle and idle started fluctuating and died out relatively quick, noticed when i was downshifting to make turns, that the idle slowly dropped like normal then dipped down hard when i hit the clutch to downshift. Ive also swapped out ecu's and still no fix, next im going to put in a new O2 sensor and see if it changes anything.

If anyone has suggestions please reply, thanks

Ok have you even given a thought that it might be your tps senser ?

no.... i have not..... ill look into it and update....thanks for the suggestion

**update** switched out the o2 sensor, no change....was getting ready to check the tps sensor but my volt meter is trash and need to buy a new one. When I give the throttle a lil go and release the motor wants to die out. Ill be buying a good volt meter and testing the tps out on Sunday, and will update the results. If you got any other ideas on what it could be let me know. Thanks

**update** ok after switching out the tps, and adjusting it to the proper voltage. I started the car up and drove it around....seemed to be running like normal, so I drove it to the gas station to fill up the tank since it was running empty. On the way home check engine light came on and started seeing idle fluctuations again, not as strong as before, but you can tell something was clearly going wrong.

Hoping that I wouldn't get another code 55(no malfunctions) I checked the ecu code, I got 2 codes, 13 and 45. 13 is Engine temperature sensor circuit and 45 is leaky injector. Code 45 is a old code that came up back when my injector #3 was shorting out, I'm assuming its coming up because the code was never erased. Code 13 is new, from what I'm reading up on it, it means I have a bad coolant temp sensor or connection and will cause my car to run rich, give me bad mpg, and even stall out the engine.

Anyone who has had experience with code 13 and can give me some helpful input; would be much appreciated. Thanks

Ok so it did calm it down some then that's good. Now did you get a new tps or used. And if it's still doing it. sounds like you might have a vacuum leak. Have you checked the hose that goes from the brake booster to the manifold? some times the hose after the one way valve has a hair line crack right where it bends. And also if your getting a temp senser fault just change it out. It's only like ten bucks at autozone.

Oh yeah did you change out the pcv valve. That's one of the main things people. Forget to change. Well On 240sx duel I don't think they forget I think they really just ignore. Haha cuz its a pain to get to.

Ok well I haven't seen anyone mention this, have you checked your CTS (coolant temp sensor)? There are two sensors one is a single wired plug, that one sends signal to your gauge cluster to tell you the temp, the other is a two wired plug usually red in color, that's the one you want to check, that sends signal to your ecu telling it if the car is warm or cold, that could be your problem, it probably thinks your car is still cold after the car is at full operating temp, but if the sensor is malfunctioning it's still telling the ecu your car is cold, causing it to dump more fuel like the if the car was still in the warm up process, causing your engine to flood with fuel, next time you warm the car up and it starts acting like that just leave the car running (if it stays on) and go under the hood, find the red 2 pin sensor and disconnect it, see if your idle changes and stays running

subscribed~
i too have a '91 240 hatch with a KADE.. been noticing the idle is starting to fluctuate after the car has warmed up a bit. good luck with your fix! would like to know what happens~

Forgot to add, check on the CTS connector for any kind of corrosion that will cause it to do that too

Mine did the same thing. Check the compression on all 4 cylinders. minimum should be 150psi normal is 171psi. If you're reading is lower than 150psi you may have a bad compression.

any new updates on this?
i was getting a code 45 so decided to get a new set of injectors..still got a code 45.

are you still getting 45?
what else could it be if not the fuel injectors?

its probably the coolant temp sending unit thats bad, mine did exactly the same thing you are describing, i pulled a sending unit off a junk car and its good as new havent had any problems since

i know this is probably really late but ive had this problem and fix it

you have a couple options here:

1) change your fuel filter

2) change your fuel strainer (sock)

3) drop the tank and have it cleaned out

you might just have dirty fuel cause thats what happened to me

so hope this helps

I had the same problem I had a loose positive alternator wire, and also I had swaped my fan shroud from a CA18 on my KA24 but when you do this the hole that connects from the intake to the radiator fan shroud is exposed. You need to plug this hole if not it will cause the car to idle rough... basically a vacuum leak. check all your cables and vacuum hoses.

if u need i have an idle stabilizer it fixed all my idle problems

i upgraded my fuel filter to a z32 fuel filter a few days ago.. (there was a lot of 'f's in that sentence..lol)

she's been running good so far and the check engine light went out~
we'll see if she keeps it up~

Check the injector o rings, if they go bad fuel will leak past injectors and cause engine to idle irratically and run rich, also ect sensor will cause idling issues

check engine light came back on for awhile and wouldn't go away.
got leaky fuel injector, egr, and something else..(which im sure was just a chain reaction..means nothing)

decided to clean the MAF..
$9 and 30 minutes later..
she's running fine, no idling issues, no check engine light.
it's been a couple days since then..light came on once but went away pretty quickly.
..and been :snoop: since then~

I'm having the same issue with my SR. It runs fine, pulls hard...it's just when im trying to idle it.

I have the stock ka single cam fuel filter, I'm going to change it out and see if that fixes the problem!

Had these same problems. Replaced maf and iacv to no avail. Finally decided to just do a tune up. Problem solved. Rotor, cap, plugs, plug wires, and coil. No more issues.

Sent from my piece of shit Android using that piece of shit app Tapatalk