Bad hesitation at low RPM

[sgtjeremyh]

My 92 240sx se has bad hesitation at low rpm's. If i get on it it clears up and runs great until rpm's drop back to 2500 or so. Ive replaced plugs and wires, and i have a set of injectors on the way. Do you think this will fix the problem? Or could it be a sensor, causing the engine to get to much fuel. Other than this problem the car runs great and some days, it decides not to hesitate...

Thank you for any advice..

Modified by sgtjeremyh at 3:19 PM 11/1/2005

Modified by sgtjeremyh at 3:20 PM 11/1/2005
Modified by sgtjeremyh at 11:31 PM 11/1/2005

[sgtjeremyh]

Is there any special way to pull these injectors, or do i just unplug them and pull the lil plate off, and twist them out?

[Ni2s4s0aSnX]

No, definately don't do that. You will have a big mess on your hands if you try to just pull out the fuel injectors. Well, here it goes, I'll have to walk you through it. Well first you have to relieve the pressure in the fuel system. You do this by first taking off the gas cap, and then start the engine until the engine bogs out. Then dissconect the negative battery cable. And after you do that, then you can take out the fuel injectors. To remove the fuel rail and injectors on the KA24E you will need to remove the BPT valve before you can take off the fuel rail. You have to remove the two bolts on the top of the BPT valve in order to remove it from the top of the intake manifold. Then there are three vacume hoses attached to the BTP valve, two small ones on top and a medium sized one underneath it. Once you have the BTP valve off, then remove the two bolts on either side of the fuel rail that attach it to the intake manifold. Once you have that off then the fuel rail sould come right off. Then you can dissconect the fuel injectors from the fuel rail. On the KA24DE you will not need to remove the BPT valve in order to remove the fuel rail. You will need to replace the o-rings and other rubber things when you do this job.

[Ni2s4s0aSnX]

Well, to actually answer you first question, the fuel injectors very well may be the problem. When was the last time they were replaced? But you also could have a sensor problem, you just have to test different things to find the problem because it could be one of many things.

[DjPantsSpecR]

If you have a dead injector its probably alot easier to measure the resistance across it before you start trying to pull injectors, thats a mistake i made

this will only show you a dead injector however, but a dead injector will make the car idle like butt, and then it doesnt rev smoothly it putts up in rpms, and this is only one dead injector

injectors are teh best place to start. then maybe mafs and cts and maybe aicv, but i'll bet my money on a bum injector

[sgtjeremyh]

to my knowledge, the injectors havent been replaced. They look like they've been in a while, so that could be the problem for sure.ThxBy the way, i dont like taking my car to have it checked, unless i just cant fix it, so how do i test the injectors? what kind of instrument do i need?

[sgtjeremyh]

yes,it apears i wouldve had problems the other way, and thank you very much for the step by step, this will help me alot......

Thx again, ill let you know how everything turns out..

[Ni2s4s0aSnX]

ohm meter to measure the coil resistance of the injectors. Also, a little tip, go to your local Autozone or Advanced Auto Parts or whatever store you usually go to, and pick up a Chiltons for the 240sx, that will answer many of the questions you have asked here today, it'll be one of your best investments.

[sgtjeremyh]

how many ohms should the injectors be reading, and is this done with car running, or off? I dont mean to sound like an idiot, but i havent really dealt with alot of fuel injection vehicles.. Thx..

92 240sx se

[AeonTorpor]

The injector should be measuring 5 ohms according to the fsm. (amended) car off!!! (/amend)

I had a blown o-ring and a bad injector on mine, so check the resistance before you go pulling away and be sure to follow the procedure to extract the injectors properly. I made a mistake and it washed my piston rings, 10 quarts of gasoline in my oil (a very bad day).

Oh yeah, if all the resistances are fine, it'd be best to determine which injector's o-ring busted before pulling a single one, cuz the messed up one would be the only one you'd have to pull, and trust me, pulling the injectors out intact is a b****.

Good luck.
Modified by AeonTorpor at 4:30 PM 11/3/2005

[eddiec]

to add to what someone said above, after you open the gas cap you have to pull the fuel pump fuse so its OFF. if you forget this step the system will still be pressurized when you start wrestling with the squirters. after pulling the fuse crank it over and let it run til it dies. then crank a few more times to get as much of the go juice out of its veins so its doesn't spit on you when you disect the cylinder irrigation system.

[Ni2s4s0aSnX]

Oh, yeah, crap. I forgot that, you need to remove the fuel pump fuse, and then disconect the battery cable.

[sgtjeremyh]

What are the plastic tips on the spray end of the injector called? and where can i get new ones?

[deviousKA]

The injectors should measure 12-14 ohms resistance.

The plastic ends on the tip of the injector are called pintle caps, injector service/cleaning shops would be the best place to check for replacements.

Edit: BTW, you check the resistance of the injector when the car is off, just unplug the injectors electrical connection and measure across the two pins. Any basic voltmeter will do the trick.

It would be a good idea to run the codes on your ecu to see if it is picking anything up in regards to your hesistation.

[sgtjeremyh]

run running a check on ecu codes, u mean take it to a shop, and hook up to computer? or is there something i can buy to do this with? Anyway i checked all injectors, and they all run about 12ohms, including the other set i have. How am i gonna figure out which orings are bad, so i dont have to pull eveysingle injector?

[Chezedik]

Is it possible that it is in limp-home mode.

[sgtjeremyh]

SHHH!!!!!!! the car could hear you. But for real, I dont think the cars on its last leg..The engine oil,looks as good draining out , as it did going in.. Compression is good, no smoke, nothing that would lead me to think that.Now just let me go outside and bring the car in and let it sleep inside tonight,, you prolly hurt its feelings...

[Chezedik]

No, it's a deal on the Nissan ECU, called Limp-home mode. If you have an MAF or TPS fail, it will not let you drive above 2500RPM, then it cuts fuel and you fall back down. If you mash the gas at 2.5K it feels like it is flooding bad. It is telling you there is something wrong enough that it cannot properly control the engine, but runs on a baseline to get you home. Had it happen to me when I was dumb enough to cut a scoop above my MAF and got rain in it. It was a noob mistake for sure. But that is something to think about. You can read up on it in the FSM. On the 240sx forum you can download either an S13 or S14 FSM, and it's a sticky, so it's easy to find.

[Chezedik]

Paid 75 for mine, so get it free unless you need the mobility that bad (I did).

[xTearsFallForeverx]

well if one of his injectors was bad... his rev wouldnt clear up when he hit higher rpms. the engine would still hesitate. i dont think its an injector. prolly iacv or tps and to check your ecu for codes you dont have to buy anything. just go to the passenger side kick panel and take it off. remove the bolts holding your ecu to the kick panel. then visit here http://www.240sx.org/faq/artic...h.htm

[sgtjeremyh]

i get code 34, knock sensor? does this even have anything to do with hesitation?

[xTearsFallForeverx]

what exactly do you mean by hesitation, when you are at WOT the engine feels sluggish till over 2500 rpms? or is it missing until 2500rpms? Bad knock sensors usually cause the car to feel sluggish and sometimes hesitate between shifts because the ECU retards the timing.. but it usually happens in the upper rpm range. Try resetting your ECU and see if you get the code again. If so you may need a new knock sensor. its under your intake. check the harness for it first though. they tend to break on the KA for some reason. if you have to replace it, the easiest way would probably be to take off your oil filter and maybe even your starter to make things easier.
Modified by xTearsFallForeverx at 4:32 AM 11/27/2005

[sgtjeremyh]

its gotton worse now, its not just under 2500 rpms. It hasa sluggish feel, as if maybe its flooding. I can hold the accelerater at an even low area, and it spudders and cuts back, then without even giving it more gas, it clears and jolts. But it does smooth out a bit, but at red lights, it tends to start the same way with the cut back.

[xTearsFallForeverx]

id say just reset your ecu, start it up again, drive it around for a few minutes then check to see if you are pulling the same code. if so then you need to look into getting a new knock sensor or knock sensor harness.