92 240sx KA Random Hesitation, rough idle HELP ME!

[jbrown]

OK guys I'm going to be a little long winded as this problem is odd. Please don't tell me to search because I have and I've tried everything that previous topics have suggested for the most part, so I'm hoping someone can help me out through my own post;

I just bought a 92 240sx, BONE stock... It was a few days before I had the first hesitation happen. I was just driving and all of the sudden boom, the cars making no power. It felt like it was running on 3 cylinders. This car is going to be a track car, so I can't have this. So I do plugs, wire, cap and rotor. Seems to fix a lot of roughness issues, but then sure enough a week later, it's doing it again. On and off it keeps doing it, every few days and no real temperature/humidity similarities that I can see....

So then I change the fuel filter and air filter, again making the car a lot better all around. Sure enough, tonight (a week later) I drove the car about 60 miles, park, an hour later I need to run to the store and it's doing it again. I come back from the gas station, park it and then my friends get there... I start the car to show them and it's gone....

So the only things we can come up with are;

1.) It's randomly not getting spark, but on which cylinder we don't know... but it does feel like it's running on 3 cylinders when it does it, but then 3 seconds later it can be fine...

2.) An injector could be sticking, but again, you'd think it would do it more consistantly...

3.) The MAF is going bad, but also you'd think that wouldn't have 1 week periods where it was fine.

4.) Possibly the o2 or maybe a combination of things like TPS, IACV, or emissions BS...

5.) It could be getting no spark, but I've replaced all the ignition stuff besides the coil and distributor itself... possibly a bad ground?

6.) Maybe a timing issue? But you'd think that ALSO would be constant...

7.) The cat could be clogged as I did have a similar problem on an older car before, but with a clog usually it doesn't effect WOT situations as much as partial throttle... I do have an exhaust leak and the cat is probably original...

But yeah, we have a lot of ideas but I'm in no position to waywardly being spending hundreds of dollars hoping that eventually the problem goes away... This is my first 240sx, and I'm used to Honda's which have a lot of different components and are different animals in a way... The MAF thing is new to me, so who knows. Any and all input would be much appreciated as this car has to be ready very soon as the track season opens and I'm going to look mighty silly if I've got a fully prepped car that gets outrun by someone on foot...

I also want to add that the car idles a bit rough, on and off, all the time. But when the hesistation is happening, it idles especially rough. Like the shifter's bouncing all over the place...

Sorry about the friggen novel I wrote, but better to be in depth...

Thanks in advance for any and all help!
Modified by jbrown at 10:22 PM 5/2/2007

[jbrown]

morning bump.... cmon guys, help me out

[positron1]

Just start with the basic stuff like cleaning your MAF, throttle body and checking your vaccuum lines for tears or leaks. Check that and see if the performance improves, then let us know from there.

[thrusday]

my 1990 240 is doing the EXACT same thing.. Except it dosen't even light up anymore.. now it barley wants to start.. I feel like I'm on a rollercoaster when I'm sitting in my car because it shakes so bad just idling.. If we CAN get it up there, it does "alright' once we get it up to 3,500-4,000 rpms.We replaced everything that you did and we're still out of ideas.. Anyone wanna shed some insight?

[jbrown]

no joke dude... i need help with this... the only new thing ive kinda noticed is that it seems to do it when im low on gas, so perhaps its fuel pump related... but yeah, tomorrow im going to put my new intake on, so while im at it im going to clean the crap out of the throttle body and MAF and see where that gets me... then I was thinking about replacing the o2 sensor and fuel injectors/rail.... other than that, i really dont know what to do!

[thrusday]

We were screwing around with the car today and this is what we've gotton so far, well, the newest ideas we have as of now.. We took off the cataylac converter because we thought there was a clog in there somewhere, but turns out it's fine.. Though there is a hell of a lot of white smoke coming out of the pipe.. But, we took the fuel pump cover off and there are 2 lines that go to the fuel pump. There's one line that goes directly to the fuel tank. We think it's either the wiring back there or one of the fuel lines because when we messed with them the idling got a 'little' better, though it's still backfiring like crazy. There's a lot of carbon buildup in the emissions controls, (which we plan to rip out soon) AND we have suspicions that gas is coming back OUT of the intake tube, because there is a hint of a smell of the gas, which is why we think something is up with the emissions..

So to make a longer story a little longer, we're taking the rubber hoses off the fuel pump and fuel tank, check for clogs and we're going to clean the fuel pump strainer..

So hopefully something good happens here because this is the last thing I can think of.. Hell.. This is all that's LEFT to check!! But if you come up with the answer to these problems and fix what's wrong, let me know! I'm going nuts here!! I just need this engine to last at least 5,00 more miles then I can get my SR20DET dumped in there.. I wish I could get it now

[MJDalton]

It's your injectors, If when it acts up, you can see the engine rock from side to side and your shift knob is all over the place. Pop the hood, remove on injector connector, If that one is OK the car will almost stall. Plug it back in and move to the next one. Keep doing this until you get to one that has no effect on the engine. That's your bad injector. I would say that if one is failing replace them all. I figured it would be cheaper and easier to just replace one. Eventually I had to replace them all.

Good LuckMike

[thrusday]

I found oil on the tips of 2 spark plugs. So I'm hoping it's not a valve problem. But I'm putting in new fuel injectors, hopefully tomorrow.. I bought this car not even a month ago.. I was looking at the fuel lines and I believe the guy who sold it to me when he said that it was sitting for 6 months. There's definentley bad gas in there.. The lines looked like they had sludge in them.. So.. New fuel injectors and possibly new fuel lines..

I just want this car to RUN!

[Numby]

i have the same exact problem. I replaced all the Fuel injectors, o-rings, fuel rail - Fuel pump spark plugs rotor d-cap wires, it still wont go away. I do have a valve tick in cylinder 3 if im hearing it right. Oh well whatever

[stopatnothing]

your best bet (from personal experience) is probably what MJDalton said and check the injectors. Other than that I would move right on to a bad ground because thats what fixed mine. I cant remember where it was but as soon as that was fixed I didnt have any more hesitation issues or anything of the sort. Mine was a terribly combination of both and it confused the **** out of me.

[thrusday]

We've only found 4 grounds on the car so far.. One on the exhaust, one on the transmission, 2 on the engine. .Where are some more grounds just in case that's the problem....

I did an ohm test on the battery to chassy and got a .2 reading, so that checked out.. Maybe my battery amps or screwed up or something..

I'm ALSO hearing a valve tick in piston #3.. It sounds like piston #3, but I'm not sure. What I really want to know is... Why do I have oil in piston #2 and #3? How can faulty injectors cause oil to enter the combustion chamber? I pulled out the spark plugs and there was oil on the tips of the plugs of pistons 2 and 3... Is it oil.. Or gasoline soaked carbon? We have A LOT of carbon buildup in the intake manifold... I'm about to just rip it apart and clean the s**t out of it.. We're getting a backfire OUT of the intake on accelaration and there's blue smoke coming out of the exhaust.. When it gets up to about 3-4,000 rpms, she lights up.. This problem gradually got worse over the course of about 3 days, but now it's not getting any better or any worse.. Should I rip the head off and take a look? I really don't want to, but hell.. I think I may have to..

[jbrown]

yeah i checked the resistance on sunday and it was fine... can one of the other grounds be bad if the main one is fine? I mean i know that the exhaust ground is bad, atleast i think it is... when i did my trans mount last week i noticed a random wire hanging down by the exhaust and i dont think it touched anything, so im assuming it broke off... but how important is the exhaust ground really?

[stopatnothing]

well that all just depends... Do you have a heated o2 sensor? Because if you dont, its not too important. But if you do, then you dont have a complete circuit and your o2 sensor will be registering incorrectly.

[jbrown]

i dont know if it's heated or not... its a 92, would that tell you? I thought if they came stock, they had it, and if not, they didnt...

[stopatnothing]

I'm not sure, I would venture as guess as to say its NOT. But if you can check how many wires it has that will tell you. One or two wires = not heated. 3-4 = heated.

[jbrown]

So yeah, this morning it was running like crap suddenly... so when i got to work, I started pulling injector wires and behold! The cyl closest to the firewall (#4?) didnt change the idle at all! So i guess that's it? It must just be sticking shut sometimes?

[thomasjamal]

So yeah, this morning it was running like crap suddenly... so when i got to work, I started pulling injector wires and behold! The cyl closest to the firewall (#4?) didnt change the idle at all! So i guess that's it? It must just be sticking shut sometimes?

So I've been having almost the exact same problem. Except that I started with this problem:

How can faulty injectors cause oil to enter the combustion chamber? I

I thought that my injectors were leaking and washing out the rings or valve seals and causing oil to leak in and burn, producing a bunch of white smoke.So I pulled my injectors and realized I needed new injectors.

Then I replaced all my injectors and o rings but now the car was running on 3 (shaking violently like one of you described... it actually shook so much the fan ripped a hole in the shroud!). Oh, and as I replaced fuel injectors again the non-working cyl would move around. All four were out at different times.

Long story short I replaced my ECU. Now the car is running on all four but the idol is out of whack and rough and it hesitates like crazy.

So next I'm going to adjust my timing and I'm really hoping that will fix it...