240sx Low RPM Hesitation

[kholistics23]

I started having an issue with my s13's acceleration. Whenever im accelerating under 2k rpm.. there is a lot of hesitation or bogging before it drives up normally again. Im not really sure what would be causing this. So if anyone could tell me some of the probable cause for this.. i would appreciate it very much or if someone could help me out. Thanks! :D

[Croustibat]

It could be a bazillon number of things.

converted to computer langage, what you wrote equals "my computer does not work".

Most common problems are dying fuel pump / not enough fuel and boost leak. Check those first. Check your plugs too.

[kholistics23]

well when i purchased the car it was running perfectly fine then i went home and then one of my fuel injectors went bad and made my car shaky. Which then caused my engine mounts to break. I finally got my engine mounts and fuel injector changed but my car hasnt ran the way it use to run before. There was some hiccups when i put it in "drive" (automatic) but would be fine when i was in neutral or park. It wasnt really too bad, but i finally decided to convert my car to a 5 speed and when i got the car back it was driving fine also (the car was warmed up). When i went to go out my car started hesitating and bogging at low rpms but would befine around 2k or more rpm. So idk if its just the car not warmed up thats causing this or something else. i just want to get it fixed because i want my car to drive like how it use to when i got it. :(

sorry for this long passage...lol

[Croustibat]

your injector problems does not look promising though, i hope it did not damage the cylinder.

so, what you could do :

for free:
check for boost leaks and loose injector / coil pack connectors
check your CAS is at the correct position and not varying (although that is not a common issue)

$:spark plugs, fuel filter

$$: fuel pump

If it still does not change anything, it could be a head / rings problem.

[dpak]

maf, tps, knock sensor..
check fuel pressure?

[89JDM240sx]

^ agreed also check for Vac leaks I'm assuming your car is all motor? If not your air/fuel could be off

[Mishkin_707]

Check your CTS, common on 240's make all sorts of problems

[kholistics23]

idk if this is any valid information, but it just hesitates really bad when i press down the gas somewhat hard. if i slowly press it, the car doesnt really hesitate. only when im on 2k or less rpm and when i pressed the gas somewhat hard. so idk im guessing it could be a sensor?

[kholistics23]

^ agreed also check for Vac leaks I'm assuming your car is all motor? If not your air/fuel could be off

yeah my car is stock ka24e. im also thinking that the air/fuel mix is off.. but i just dont know where to start. lol

[Croustibat]

idk if this is any valid information, but it just hesitates really bad when i press down the gas somewhat hard. if i slowly press it, the car doesnt really hesitate. only when im on 2k or less rpm and when i pressed the gas somewhat hard. so idk im guessing it could be a sensor?

Definitively a fuel issue. Fuel filter change, then fuel pump change if the problem is not sorted. Check the voltage too, sometimes the wire ages poorly and goes bad. I have seen readings as low a 9-10V, instead of 14V when engine was running. If this happens, clean the connectors and/ or change the wire for a bigger one.

If someone can lend you a fuel pump assembly, try it. i am quite sure it will solve your issue. It is very easy to change, although you might have trouble refitting the big oring ( get one new, or put it in your fridge for some hours so it shrinks again)

[Kiro1968]

A bad MAF can also cause similar systoms. Unplug the MAF and make sure the pins inside are straight and are not bent, if they aren't bent make sure the socket connection is good. Test the MAF to make sure its functioning properly.
The car will run in safe mode without the MAF, it allows you rev up to 2500krpm but not over that. If you slowly rev it up, it'll go over the 2500krpm limit.

Just a thought ^_^

[kholistics23]

im not sure if this is a valid information also, but the car hesitation gets worse when the weather or the engine is cold. There are also sometimes a hiccup on the car when im idle. i just gotta figure out if its more a fuel problem or a sensor problem. thanks! :D

[Croustibat]

if you continue driving like that it will be a piston problem.

[kholistics23]

if you continue driving like that it will be a piston problem.

how would i be able to fix it? you think its more of a fuel problem or sensor?

[RyanS13]

I don't know if you've tried this or not, but disconnect your battery for about 5 minutes. The CPU might be in safe mode. It's happened to me before.

[kholistics23]

I don't know if you've tried this or not, but disconnect your battery for about 5 minutes. The CPU might be in safe mode. It's happened to me before.

ill try it, but sometimes my car runs fine, but out of nowhere it would do the hesitation. i tried seafoaming the car to see if itll run any better, but no luck. :(

[iamtheyi]

ill try it, but sometimes my car runs fine, but out of nowhere it would do the hesitation. i tried seafoaming the car to see if itll run any better, but no luck. :(

lol seafoam is not your end all be all car fixer haha. That's just some maintenance additive to clean off carbon build up. If your tight on money, do what people have said and try all the free stuff. Check voltages, vac lines, spray intake cleaner into the iacv, clean maf, etc. Then replace cheap stuff you have to anyway starting with fuel filter. Then step it up one more notch and start replacing stuff like the fuel pump.

[kholistics23]

lol seafoam is not your end all be all car fixer haha. That's just some maintenance additive to clean off carbon build up. If your tight on money, do what people have said and try all the free stuff. Check voltages, vac lines, spray intake cleaner into the iacv, clean maf, etc. Then replace cheap stuff you have to anyway starting with fuel filter. Then step it up one more notch and start replacing stuff like the fuel pump.

im starting to think its a somewhat faulty fuel filter though, because that was the only thing that was changed. you think that 1 fuel filter cna make the car hesitate. my car has a small hiccup on idle also.

[iamtheyi]

Think about it this way, a clogged fuel filter does what? slow down the flow of fuel going into the combustion chambers. Giving you less fuel and hesitation/bogging etc. It's something that is routine anyway so why don't you just throw a z32 fuel filter on it and see if it changes anything.

[kholistics23]

Think about it this way, a clogged fuel filter does what? slow down the flow of fuel going into the combustion chambers. Giving you less fuel and hesitation/bogging etc. It's something that is routine anyway so why don't you just throw a z32 fuel filter on it and see if it changes anything.

cos one of my fuel filter went faulty. so my mechanic changed just that one.. so i was wondering if its the new fuel filter thats causing it. is it cos its a wrong fuel filter thats causing the bog or is it because i didnt change all the fuel filter?

[iamtheyi]

cos one of my fuel filter went faulty. so my mechanic changed just that one.. so i was wondering if its the new fuel filter thats causing it. is it cos its a wrong fuel filter thats causing the bog or is it because i didnt change all the fuel filter?

Fuel filter is not fuel injector. Think you're getting it confused right now ><. If you think it's your fuel injector, the easiest way I know to check if it's working is to listen for it's pulses. Get a metal rod/stick and hold it up against the back of the injector and listen of the ticking. Should be pulsing consistently. Other way of course is to get a fuel pressure gauge.

[kholistics23]

Fuel filter is not fuel injector. Think you're getting it confused right now ><. If you think it's your fuel injector, the easiest way I know to check if it's working is to listen for it's pulses. Get a metal rod/stick and hold it up against the back of the injector and listen of the ticking. Should be pulsing consistently. Other way of course is to get a fuel pressure gauge.

haha my bad.. i meant fuel injector. i had an air head moment and didnt read what i was writing, but i actually meant injector. my bad.

[Croustibat]

Fuel filter is not fuel injector. Think you're getting it confused right now ><. If you think it's your fuel injector, the easiest way I know to check if it's working is to listen for it's pulses. Get a metal rod/stick and hold it up against the back of the injector and listen of the ticking. Should be pulsing consistently. Other way of course is to get a fuel pressure gauge.

that will tell you the injectors are opening and closing, not if they are blocked by goo or not.

[iamtheyi]

But he's wondering whether or not the injector is functioning properly because that's the only thing that has been replaced. If it is functioning properly, it will tick. If not, it's not working lol.

But that's one of the free things he can do. If it is working, replace fuel filter and work from there is what I'm saying.

[kholistics23]

But he's wondering whether or not the injector is functioning properly because that's the only thing that has been replaced. If it is functioning properly, it will tick. If not, it's not working lol.

But that's one of the free things he can do. If it is working, replace fuel filter and work from there is what I'm saying.

could it be possible the the one that got replaced doesnt tick at a steady pace? could it make my car bog and make my car hiccup on idle?

[Johnny_K]

I had a similar issue and it finally didn't start up one day. Turns out mine was a bad cool wire.

[kholistics23]

so how do i exactly test out my fuel injectors if they are working?

[Croustibat]

But he's wondering whether or not the injector is functioning properly because that's the only thing that has been replaced. If it is functioning properly, it will tick. If not, it's not working lol.


Yes. but it does not mean that if they tick, they work correctly.

If it gets stuck open, or has a different flow/latency, it wont show.

Anyway his injector is working as the problem only shows on low rpm. An injector that does not "tick" means the cylinder is eithem empty or hydrolocked, so he would be running on 3 cylinders either way.

If it comes from injector replacement, my bet would be on the injector O-ring. At idle there is a lot of vacuum so unmetered air could enter there.

these orings are worth a couple of $ .

[srking]

my car has the same problem and i changed the fuel pump and filter plugs wires and dizzy rotor and tps maf but still nothing i was starting to think that is was off timing

[kholistics23]

Yes. but it does not mean that if they tick, they work correctly.

If it gets stuck open, or has a different flow/latency, it wont show.

Anyway his injector is working as the problem only shows on low rpm. An injector that does not "tick" means the cylinder is eithem empty or hydrolocked, so he would be running on 3 cylinders either way.

If it comes from injector replacement, my bet would be on the injector O-ring. At idle there is a lot of vacuum so unmetered air could enter there.

these orings are worth a couple of $ .

Just wondering.. don't call me a noob, but why is it that when the car is warmed up my car doesn't hesitate as much anymore, but still have the hiccups on the idle though. But when its cold it hesitates so uh that I bounce around inside sometimes. Especially on first gear.

[kholistics23]

Yes. but it does not mean that if they tick, they work correctly.

If it gets stuck open, or has a different flow/latency, it wont show.

Anyway his injector is working as the problem only shows on low rpm. An injector that does not "tick" means the cylinder is eithem empty or hydrolocked, so he would be running on 3 cylinders either way.

If it comes from injector replacement, my bet would be on the injector O-ring. At idle there is a lot of vacuum so unmetered air could enter there.

these orings are worth a couple of $ .

Just wondering.. don't call me a noob, but why is it that when the car is warmed up my car doesn't hesitate as much anymore, but still have the hiccups on the idle though. But when its cold it hesitates so much that I bounce around inside sometimes. Especially on first gear.

[kholistics23]

so i recorded a video of how it acts. so if someone can help me out or something. 240sx Problem - YouTube (http://www.youtube.com/watch?v=bVarrFyEsFQ&feature=youtu.be)

[Croustibat]

Just wondering.. don't call me a noob, but why is it that when the car is warmed up my car doesn't hesitate as much anymore, but still have the hiccups on the idle though. But when its cold it hesitates so much that I bounce around inside sometimes. Especially on first gear.

I cant say. Diagnosinc when being 8000km away is hard, i gave you the most common reasons for your problem based on what you told here.

If you had an AFR gauge and a wideband sensor, you could see what your fueling looks like, but you dont have that and it will be cheaper to just change the fuel pump and filter.

I cant hear the sound of the video (i am at work) but your idle speed looks awfully low to me. Is it usually that low on KA engines ? If it can keep that idle speed, there should be no boost leak (it either causes high idle or engine stall).

If your fuel pump is still the oem one, start by replacing it and the fuel filter.

Also check your temp sensor, idle should be accelerated when cold and it does not look accelerated at all.