my 240sx is failing on me miserably!!

[topless_240]

My Symptoms:1) HORRIBLE hesitation2) rough idle (starts up fine but quickly wants to die off, have to rev it to stay alive.)3) Has not let me go over 4,000 rpms4) takes forever to get up to speed5) will shake sometimes at speeds of 55 - 606) floor it and it doesnt go anywhere!!!!

Ok here's the problem I bought my 240sx (ka24de) knowing that it was messed up. The guy I bought it from told me that he took it to a mechanic and they told him that one of the injectors were faulty. So I replaced that to find out that it didn't do anything. I then did a slight tune up replacing the fuel filter, air filter, oil, plugs, rotor button, and distributor caps. That didn't really do much of anything either. I then messed around with it some more and I found out that my cat was busted and was clogged, so I took it to get changed and it ran a little better but then started to run worse. I also tested the maf by unplugging it, and it idled a lot better. So I got another maf and it did the same thing.

I let it sit for a day or two cause I was tired of messing with it, and then I took it to a mechanic who is a buddy of mine and we did numerous test on it. We did a compression test to find that it was 135. Diagnosed the ecu and received a code: 34. He said that he wasn't receiving any vacuum numbers in any of the lines either. We did find out that one of my spark plug wires (which I didn't replace) was HORRIBLE. It would barely sit on the plug, I know that is one of my problems but I still don't think that's all the problem.

Please someone help me out, I don't know what to do anymore.

[topless_240]

bump

[danielsan]

your compression is 135 like on one cylinder? what are the others showing?

because thats kinda low and would be your problem.

[topless_240]

it was 130, 133, 135, 135 and yea I know that's kinda low but It should still have some spunk left in it.

[1unar3clipse]

try a good known ECU, check plugs, wires, injectors.

[topless_240]

Well I know my wires are shot so I'm going to replace them tomorrow and update you after that

[Rucca]

Code 34 - Knock sensor

That is a large contributor to your problem. Besides that, check for vacuum leaks, and definitely replace the wires.

[topless_240]

yea but the knock sensor shouldnt make it run like that.

[r3v_v3ng3]

yea but the knock sensor shouldnt make it run like that.

yes it will because it will pull timing.

also check your egr components. it could be a culprit specially the hose from egr to back pressure transducer.

[low91240sx]

Yes the knock sensor will mess your S*it up bad man replace it.. have someone will small hands do it or else your going to have to take the top part of the intake off.

[topless_240]

I know that it will send weird stuff to the ecu, but it shouldnt make it drive like that should it?

[1unar3clipse]

^ I wouldn't think so.. I'm running on the knock sensor code and the car is running fine, but I am expecting my new sensor to arrive someday... (never order from a dealership where the parts guy tells your to look up the word "skyline" to find a knock sensor )

Either way you might have that code being sent and maybe another issue along the vacuum lines, or possibly AIV/PAIR valve issues.

I'm hoping a more experienced mod or member would come across as I'm not one for troubleshooting without seeing/hearing the problem.

[topless_240]

ok ok ok, I think i've sourced the problem well today I went and got some new plug wires, and I went to crank it up and it started right up fine. Then quickly died off, so i went to the throttle body and revved it up with my hand and let the car warm up some. I hince this weird hissing sound (sounds like someone sucking on the end of a straw, or a nitrous shot...lol) near the throttle body, intake manifold area. I put my ear closer and everytime i give it gas, it makes the hissing sound. Does that not sound like a vacuum leak to you?

[Vegascorbin]

Yep sounds like a vacum leak to me.

[480sx]

Guys the knock sensor input is only used by the stock ecu at light to medium throttle. At WoT the knock sensor does nothing.

+1 for vac leak

[gotRB]

My Symptoms:1) HORRIBLE hesitation2) rough idle (starts up fine but quickly wants to die off, have to rev it to stay alive.)3) Has not let me go over 4,000 rpms4) takes forever to get up to speed5) will shake sometimes at speeds of 55 - 606) floor it and it doesnt go anywhere!!!!

Possible Problems:1) vacuum leak2) unbalanced wheels, might need an alignment

[BMAR240SX]

I don't know if its just the 240's i have driven but the 3 i have all shake at 55-60 or maybe lower but when you go past it no more shaking

[UNVMY240]

Thank you 480sx for speaking up on that knock sensor info. I was going to make that comment until I got down to your post.

Knock sensors do adjust timing but not so drastic that it would cause those symptoms. Good job on finding your vacuum leak... probibly wouldnt hurt to replace all your vacuum lines while you are there. If one has crack others could soon cause the same problem.

[topless_240]

Yep heres what i'm doing today:1) Replacing all vacuum lines2) replacing pcv valve3) cleaning maf

I'll update when finished

[topless_240]

Well I cleaned the maf, and throttle body, and examined the vacuum lines and i didn't really do anything different. It does idle alot better now, it sits right on 850 and then dies down like its winded and then idles back up again. But i'm going to test my vacuum lines again, cause the last time we did it there was no vacuum but I don't remember which ones they were. I know it is vacuum though for sure.

[BigMACKenzie]

On top of the wires and plugs, try cleaning out your fuel injectors, the kits with the pressurized bottles work best and are super easy to use, just be carefull not to use to much to fast. R3v_v3nng3 made a good call with the EGR check too, its a very common culprit for rough/poor idling. while you are at it, checking your o2 sensor isnt a bad idea either. Props to you for wading through this, quite a tough row to hoe, but you sound like just the joe to hoe it

[topless_240]

lol idk what you mean about the joe and the hoe, but does your vert have white leather interior if so that's sick.

[stephen240]

WATERSxCORE did you ever figure out your problem? Cause if not I know exactly what's wrong, cause the same thing happened on my 240... =] so hit me up if you wanna know....

[BigMACKenzie]

Care to share with the rest of the class Capt. Vague-Pants? Or do I need to do the secret masonic handshake and tickles your palm first?

[stephen240]

Okay so you changed all spark plugs, wires, cap and rotor. But what you failed to replace was the distributer itself. That was the problem with mine, I kept using cheaper aftermarket ones, rather an oem, I just put an oem on and WOW everything is fixed! Also check your grounds, located on driver side of the engine block on very back, there should two of them, that was also one of my problems. But yeah I did everything you did, and Its been months and months I went through 3 aftermarket distributers.

So my advice, go oem every time, its more expensive but its better.

But anyway, yeah check the distrubter cause that was my problem, cause there wasn't enough spark coming outta the spark plugs =]

Hope this helps!!! =]

[topless_240]

yea we've already checked for spark and their fine. And there is no vacuum leaks but we do think that my fuel pump is messed up, cause we checked it today and the sock is nasty dirty, and looks to be clogged near the suction part. That might of caused my clogged injector!! Does anyone have a pic of what a fuel pump should look like.

[s13bassboat]

check your throttle position sensor. i chased the same problem on my car for weeks and found the 5v. reference wire was pulling itself out of the connector. good luck

Tybrid Performance L.L.C.Nashville Tn, 37210

[topless_240]

doe anyone have a picture of a faulty fuel pump??

[Rucca]

Unless the unit has physical defects, a working fuel pump and non working fuel pump will look identical.

[topless_240]

well my sock is horribly dirty and the place where it sucks in the gas is filthy dirty and looks to be clogged, and I did have a clogged injector so that might of been the problem. And my problem just got worse and worse. Now I will crank my car up and it will idle for a bit and then just shut off. And when I try to give it gas it just wants to die out. It's horrible. We checked and I have great spark, and vacuum. So we then checked the fuel pump and it was horribly dirty.