KA24DE auto stalls when stopping (only when warmed up)

[fnmadog]

I picked up this 240sx as a second car because it's too cold to ride my bike. With hopes of maybe doing a RB25 swap sometime next summer.

Car runs pretty good, but when it's warm and I go to stop the RPMs drop to 100 and sometimes it will completely die. I've done quite a bit of searching and it seems like a vacuum problem, i've check the wiring, and hoses that I could access but couldn't find anything leaking. Had some extra time today and checked the plugs, they are pretty dirty with some carbon build up, also it looks like the air filter may have oil on it, could this be from a bad PCV? i'd like to check the dang thing but i can't find it! is it behind the alternater? i've read and reread the service manuals on this site that go over the vacuum system but can't find a good picture, and google has been as helpful as i'd like.

i'd like to replace the plugs and filter, but there's no point if they're just going to get messed up again because blow back. as i said i'd like to do the rb swap so i don't want to spend an arm and a leg fixing this ka, i'll them to pay for the rb..

many thanks!

here's the vert

[fnmadog]

I found the pvc valve its to the right of the oil filter and above the alternator. mine was bad, didn't rattle. stupid me broke off the ground bolt inside the alternator putting it back together. so i'll get the stuff to fix tomorrow and put it back together and see if this fixes the problem.

[fnmadog]

got everything back together. runs a bit better but still having the same issue. im thinking of looking into the iacv next. anyone have any thoughts.
here's a video of it from tonight after getting it back together.

http://www.youtube.com/watch?v=EjBNoANR ... e=youtu.be

[Hijacker]

Clean out the IACV. Also, consider spending the 20 bucks on a new coolant temp switch JIC cleaning the IACV doesn't solve the issue. Since it's happening only when you warm her up, I would look at pieces that are dependent of the car's operating temp.

[pepesilvia]

my car started kind of having the same problem. it dosent stall completely but comes really close...... its also an auto ka24de but an S14..... and i started thinking maybe its the transmission somehow? like when im stopped at lights itll start to stutter and i'll throw it in neutral and itll stop stuttering a little.... let me know what you figure out vuz im curious too...

[fnmadog]

picked up the temp sensor and some cleaners for the iacv (need a gasket for it though). i'll replace these tomorrow night and see if that changes anything. i'm pretty sure i'm getting terrible gas mileage too, can't tell for sure what i'm getting (odometer is broken), probably related though.

i can't say why you'd get the same issue when at a stop light but changes when you're in neutral. it might be a little different than my problem, but i'll be sure to let you know how i fix mine. first thing i did when i bought this car was run a tank of 93 octane with a bottle of seafoam, it was the cheapest and easiest step, and couldn't hurt nothing.

thanks for the replies

[fnmadog]

replaced the temp sensor and cleaned the throttle body, waiting on the gasket for the iacv to arrive, no autoshops in the area had it in stock and couldn't order it either.

issue is still there but seems a little less and the each thing I replace/do seems to make it run just a little better.

now i wait...

[blackandblue]

you didn't mention checking TPS, or timing. TPS is considered only when the engine goes into closed loop (warmed up) operation. Before warm-up, the computer sees TPS @ 100%. (throttle @ WOT).

[fnmadog]

didn't know about the tps. if it was timing wouldn't the problem be even when it is cold? i'm still learning and will be for a while i guess. i'll look up the tps today after work.
thanks for the suggestions!

[biggie]

Still didn't see you mentiont that you cleaned the IACV. That's usually the main issue with stalling at a stop.

[fnmadog]

i will clean the iacv. waiting for the gasket to arrive. i ordered a few other things for it too (stuff for the trunk so it stays open, some light cover that were broken, just small misc stuff..). didn't want to use a cut in or gasket maker when i could order one for a few dollars on the interwebs, plus i'll know it's right.

[pepesilvia]

you didn't mention checking TPS, or timing. TPS is considered only when the engine goes into closed loop (warmed up) operation. Before warm-up, the computer sees TPS @ 100%. (throttle @ WOT).

i actually took my car out today to check for vacuum leaks or even if it was my air filter (it was very dirty)... it was neither but it DID only happen when my car was warm..... and btw, my "putting the car into neutral" thing dosent really work.... what do we do if its the tps? does that mean the tps is broke? like it needs to be replaced?

[pepesilvia]

i will clean the iacv. waiting for the gasket to arrive. i ordered a few other things for it too (stuff for the trunk so it stays open, some light cover that were broken, just small misc stuff..). didn't want to use a cut in or gasket maker when i could order one for a few dollars on the interwebs, plus i'll know it's right.

btw, if you clean yur IAC, do you think maybe you could put up some pictures and stuff on how youre going about doing it? cuz i wanna try it too but i dont really know where to start...


AND ONE MORE THING.... i want you to know that when i started having this problem i replaced my fuel pump, my fuel filter, all my fuel lines, my spark plugs and wires and even put back on my stock intake pipe... but none of that completely helped.... just in-case we have the same issue here, thought this may help....

[fnmadog]

here's a link for a HOWTO on cleaning the IACV. iacv-aac-cleaning-and-testing-tutorial-t251133.html

i haven't done it yet, still waiting on that gasket. nor have i had the time to look into the TPS, today is the first day i got off before 5.

i was looking into replacing the fuel filter, but after searching no one was really suggesting that. the iacv came up quite a bit, and the more i read into this it seems to be a pretty common issue with high mileage KAs.

i think the most i'll do with this engine is replace the O2, clean the IACV, and maybe if it's not to much replace/clean/fix the TPS (as soon as I figure out what it is >.<)

[pepesilvia]

here's a link for a HOWTO on cleaning the IACV. iacv-aac-cleaning-and-testing-tutorial-t251133.html

i haven't done it yet, still waiting on that gasket. nor have i had the time to look into the TPS, today is the first day i got off before 5.

i was looking into replacing the fuel filter, but after searching no one was really suggesting that. the iacv came up quite a bit, and the more i read into this it seems to be a pretty common issue with high mileage KAs.

i think the most i'll do with this engine is replace the O2, clean the IACV, and maybe if it's not to much replace/clean/fix the TPS (as soon as I figure out what it is >.<)

my engine only has 85k on it but my iacv may still be dirty i guess..... and the TPS is the throttle position sensor....

[Jmoore124]

You don't need the gasket. I don't run one and at 10psi I don't have any leaks from the IACV housing. use either some anerobic gasket maker or even regular gasket maker, just do a good job. If you google how to clean 240sx IACV you will find an article on this website with instructions. Sounds to me with the color on your plugs and how the engine is running its either a vac leak or the IACV/Regulator. Vacuum leaks can be really tricky to find. Are you still running all the EGR stuff? Sometimes that can cause vacuum leaks. Just check all the hoses and the test pipes that come from the bottom of the intake manifold. When you have a intake leak it will run rich, which will make your spark plugs black. Good luck and let us know how it goes.

[fnmadog]

cleaned the IAVC. it was caked up with carbon goo (ps wear goggles when spraying carb cleaner...). that did help the overall issue, but it still persisted. got some solder and a new heat gun and put on a new o2 sensor. overall its 3 times better but still hunts for the correct idle at times, such as when i throw it into neutral or park, and very rarely when i come to a stop.

i'm going to check the egr as suggested and scan again for some vacuum leaks with a propane torch and test the tps, but i'm done replacing things for this engine though.. need to save for the rb25. it's driving well enough for the time being. thanks for the suggestion and help, if i find the time to do the rb swap i'll be back up here some photos and videos, but most importantly questions!

here's a link from today on how it's running.
http://www.youtube.com/watch?v=mkrq63oa ... e=youtu.be

[mechanicalmoron]

It's your TPS.

Check TPS, set idle, and make sure you have a good fully charged battery as you do the tps. It can be quite hard to tighten it down without losing your exact setting, make sure you check it during and after tightening it, and to get it pretty firm. Mine used to do that, would even die sometimes. fix the TPS and if it's still got a problem, bump the idle 50rpm. The TPS is a variable resistor, with a brush thing in it, I believe. As it wears out it's calibration will change.

bet it fixes it.

[Cone Killer]

Have you checked for trouble codes yet ? I had the exact same problem with my stock 240sx, seemed like a vacuum issue,so I ran a diagnostic on the ECU and came up with a trouble code 35 (I think that was the number) anyhow it was the knock sensor. Once I replaced it the car ran much better, but still had idle issues when warm. After I did just about everything you did mentioned above, I replaced all the fuel injectors, and now the car runs and idles perfect ! Good luck.

[fnmadog]

i'll read up on the tps this week and give it shot next weekend. that last video was during my drive to autozone to have them run the diag test, but they can only test 96 and up. being superbowl sunday and all i just grabbed some beer, bought my torch and headed home. also got an address of a local shop that'll run free diag tests for it. my dad told me it may be the injectors, but unless they're under 10 bucks a piece i'm not buying em. that's rb money.

[mechanicalmoron]

Have you checked for trouble codes yet ? I had the exact same problem with my stock 240sx, seemed like a vacuum issue,so I ran a diagnostic on the ECU and came up with a trouble code 35 (I think that was the number) anyhow it was the knock sensor. Once I replaced it the car ran much better, but still had idle issues when warm. After I did just about everything you did mentioned above, I replaced all the fuel injectors, and now the car runs and idles perfect ! Good luck.

.....I've had that code, but I'm not convinced it was a problem at all.

I do need to check codes again, but....

My motor shakes sometimes, but it did it much worse, I think my tps still just isn't perfect. I was going to do the knock sensor, but 5 hours of labor for a dieing motor didn't seem worthwhile. It's not audiably pinging. I'd say tps first.

[Cone Killer]

i'll read up on the tps this week and give it shot next weekend. that last video was during my drive to autozone to have them run the diag test, but they can only test 96 and up. being superbowl sunday and all i just grabbed some beer, bought my torch and headed home. also got an address of a local shop that'll run free diag tests for it. my dad told me it may be the injectors, but unless they're under 10 bucks a piece i'm not buying em. that's rb money.

I have about twenty years or so on how a KA24DE works and behaves (I'm probably your dad's age) the motor is basically a small truck engine, and my guess is your problem isn't a TPS issue. You need to see if your ECU is throwing any codes and move on from there; right now all you're doing is just a guess. Right now all you're doing is replacing parts or adjusting components that probably don't need attention. If there is no codes thrown then at least you have established one problem, and you can move on from there.

When I bought my car it had 220,000 miles on it and ran like crap, rough idle, stalling, etc. Even after finding a bad trouble code with the knock sensor and clearing the ECU, fixing all vacuum leaks,and cleaning every sensor, it still idled rough. Once I knew that I had no trouble codes, and cleaned all the sensors everyone has mentioned, the only thing left is the fuel injectors. Old injectors on a high mileage car will cause problems, yeah injectors are expensive, but if it means getting your car running right then you basically have no option than to replace them. Stock injectors cost anywhere from $40 to $100 each depending if you buy "rebuilt" or new.

Anyhow here's the link on how to find trouble codes on your car. Print it and read it many times over before you attempt to do it. It's really pretty easy, basically it's all about following the procedures and knowing how to turn a screw.

1991-1994-240sx-reading-computer-ecu-codes-t253912.html

Hope this helps !

[Cone Killer]

Have you checked for trouble codes yet ? I had the exact same problem with my stock 240sx, seemed like a vacuum issue,so I ran a diagnostic on the ECU and came up with a trouble code 35 (I think that was the number) anyhow it was the knock sensor. Once I replaced it the car ran much better, but still had idle issues when warm. After I did just about everything you did mentioned above, I replaced all the fuel injectors, and now the car runs and idles perfect ! Good luck.

.....I've had that code, but I'm not convinced it was a problem at all.

I do need to check codes again, but....

My motor shakes sometimes, but it did it much worse, I think my tps still just isn't perfect. I was going to do the knock sensor, but 5 hours of labor for a dieing motor didn't seem worthwhile. It's not audiably pinging. I'd say tps first.

Hi, mechanicalmoron,

If your ECU threw a code for a bad knock sensor, then it was bad. One of the few code thrown on a "OBD1" type systems that state a failed component, that's the one rings true. I've seen codes thrown for EGR valves, MAF sensors, MAP sensors, TPS etc. etc. that were thrown because of a vacuum leak or even a bad battery ground. A knock sensor either works or it doesn't in the mind of a ECU.

All I'm saying and suggesting in this thread, is that if you have a high mileage KA24DE that's pretty much stock, look at your fuel injectors and think about replacing them.

[mechanicalmoron]

Hi, mechanicalmoron,

If your ECU threw a code for a bad knock sensor, then it was bad. One of the few code thrown on a "OBD1" type systems that state a failed component, that's the one rings true. I've seen codes thrown for EGR valves, MAF sensors, MAP sensors, TPS etc. etc. that were thrown because of a vacuum leak or even a bad battery ground. A knock sensor either works or it doesn't in the mind of a ECU.

All I'm saying and suggesting in this thread, is that if you have a high mileage KA24DE that's pretty much stock, look at your fuel injectors and think about replacing them.

I think I might have just been stupid, and unplugged it instead of the tps while doing that. I haven't checked for codes again yet, probably will soon.

As for your other suggestions for him, from my similar state: I'm running on four brand new injectors.... did all four after one died, and replacing it left the motor shaking. Now it just shakes during some tempertures or throttle settings, and may run a bit lean. I still blame the TPS, which could probably use a bit more tweaking. But it generally did just about cure it, so..... it certainly had something to do with it.

It's been a few thousand more miles, so if I check codes and get a knock sensor it really is bad. Ehh maybe the shaking is it super-retarding timing due to no sensor, I dunno. And maybe the slamming motion when the injector went also took out the sensor.

[fnmadog]

ty for all suggestions! it's running well enough for now, no more stalling in heavy traffic and at stops. it still has some issues when in park or neutral, and when starting when it's warm, so it makes me think it's injectors. but as i said before i'm saving that money for the rb swap, so there's no point to put anymore money into the ka. the two things i did that had the biggest improvements, was cleaning the iacv and replacing the o2. but because this car is so old, pretty much anything i did made an improvement.

[mechanicalmoron]

ty for all suggestions! it's running well enough for now, no more stalling in heavy traffic and at stops. it still has some issues when in park or neutral, and when starting when it's warm, so it makes me think it's injectors. but as i said before i'm saving that money for the rb swap, so there's no point to put anymore money into the ka. the two things i did that had the biggest improvements, was cleaning the iacv and replacing the o2. but because this car is so old, pretty much anything i did made an improvement.

If you're talking about idle speed problems still, that is not the injectors.

And if you're talking about the motor shaking, but not actually missing on any cylinder, that's the TPS.

You can check the O2 sensor with an ECU mode, by the way. Old does not mean bad.

[s14280zx]

Make sure your dist. cap and rotor aren't corroded like mine were.