Motor Vibrations and knocking sound. . .HELP!!!

[torq32]

I recently purchased a 1990 240SX that had a complete SR20 Red Top swap in it. The car had been sitting with a blown turbo for about 3 years! I rebuilt the turbo, checked the car over thouroughly, changed all the fluids and tried to start it. It started right up and seemed to run ok. However, there was alot of noise that seemed to be coming from the head. The car vibrated really bad as well when the motor was revved up. I did a leak down test, compression test, checked the valve lash, checked the coil packs, wires, spark plugs, checked the injectors, checked the timing, and checked all of the wiring. Everything seemed just fine. I cant seem to figure out why there is so much head noise or why its vibrating so bad. I did notice a small black wire coming from the wire loom bundled in with the injectors. I grounded it and the car started missing. I unhooked it and it ran ok again (minus the noise and vibrations). I found something on the internet about an "earth ground" but have no idea what that is. My next thing is to clean the head real well and try to clean out the oil squirters and the other build up from the head. Does anybody have any ideas about what would be causing the knocking and vibrations? I am a little lost at this point so any help would be appreciated!! Thanks!

[2.5T_/<ouki]

Have you had a look at the timing chain?

[torq32]

Yeah I did take a look at the cam gears and the timing chain. The chain has no unusual wear on it and is not flat spotted or stretched much at all. The cam gears are in the position that they should be in and I checked to make sure it had the correct TDC position as well.

[2.5T_/<ouki]

Yeah I did take a look at the cam gears and the timing chain. The chain has no unusual wear on it and is not flat spotted or stretched much at all. The cam gears are in the position that they should be in and I checked to make sure it had the correct TDC position as well.


Ah, Gotcha.
You sure it's coming from the head only? May sound n00by, but have you made sure both motor mounts are tightened down? Buddy of mine did this lol!

[torq32]

Haha yeah they are tight. I did check that too. And no I'm not 100% sure that the noise is coming from the head but it really sounds like it is.

[Hoffman5982]

When you say it's vibrating, do you mean it kind of shakes? Check your injectors. Make sure they aren't leaking and/or stuck open.

[torq32]

I checked the injectors and they seem to be ok. Don't really have the right tools to test.them like the should be tested though. It runs ok when its running though. I mean it doesn't sound like its loading up or missing like it would if an injector was stuck open or closed. And the vibration is pretty bad. Like the whole car vibrates when you give it some gas.

[joeapple8]

What oil are you running?

[torq32]

Well i put some cheap valvoline in it until it ran for a little bit and then had plans to put Mobil 1 in it with another new filter. Here's what i did today. . .I was told the oil squirters may.be stuck and causing it to vibrate. I was told to drain the oil and replace it with tranny fluid. Then unhook the injectors and turn it over for a while. A good friend of mine who is a mechanic said tranny fluid helps to clean oil deposits out and hopefully unclog everything and break up any oil deposits. So i have done just that and plan to let the tranny fluid sit overnight and replace it.once again with some cheap oil for a couple miles.

[jdm2191]

Change the knock sensor

[chetos13]

check if the vac lines are correct

[joeapple8]

Dexron has a lot of cleaning detergents that is true, I would put Shell Rotella T in there and see how it works, also check all your sensors does the car feel sluggish and boggy?

[torq32]

Vaccum lines are correct. I will change the knock sensor too to see if that helps. It did have a small amount of gas in it that was about 3 years old too. I filled it up with about 1/2 a tank of 94 octane before I first started it though so i don't think it would be bad gas that would be causing it to shake unless that small amount of gas would do that. The rest of the sensors seem to be ok. I havent had the car out to drive yet. So I don't know if the car is sluggish or not. It idles good, runs up the rpm range fine without hesitations, and does not seem to studder at all. I don't have much experience with bad knock sensors. I just cant believe that a bad knock sensor would make a motor vibrate as bad as it is. we will see though!

As far as the knock sensors go, where is the best place to purchase them? Dealer, Oriely's or another auto parts store? And am I correct in saying that an SR20DET uses the same knock sensor as a 300ZX, an SR20DE, and a KA motor?

[Perfect Balance]

Get a video. So far to me sounds like an injector, Nissans are notorious for bad injectors.

[scott883]

^^ video plsss

[torq32]

Ill get a video up as soon as i can. Probably won't be till this weekend though. The reason i don't think its an injector because the manifold runs the same temp right off of all the cylinders. I tested that with a laser temp gun. Am i correct in saying that you would see a spike in temp by one cyliner if it was running lean?