93 300zx n/a knock and vibration

[datsik707]

3rd thread of problems, fixed 1 so hopefully i'll get some more answers.

1. Vibrations from underneath seats when going 35mph+
2. Just figured this out, but when letting the clutch out to soon, or such, causing the car to jolt forward, a metal to metal type tapping noise happens under the seats in the same spot as vibrations. Understandable i need to get under there and look around, just looking for first things to check.

3. Still bogging at low rpms sometimes, when below 2.5k rpm, either steady on the gas or letting of to coast, it will cut off and become unresponsive all of a sudden. Then you must tap on and off the gas until it becomes responsive again. Maf looks good, tps was corroded but cleaned with electrical cleaner.

Thanks for all the help

[t.mcginley.jr]

For the vibration and noises from under the seats, your transmission mount might be shot/gone. Could also be the exhaust banging around if the hangers are loose/broken.

And what do you mean the MAF "looks" good?

[nissanfreak12]

Center carrier bearing. This will give a vibration about 35 and will cause all the issues stated. They are expensive and most change to a one piece driveshaft.

Number three, check ecu for codes. Just because the light on the dash doesn't come on, doesn't mean the ecu doesn't have a code. Also make sure you plugged in the TPS in correctly. The plug that goes into the front of the TPS can get turned around, causing the issues as well. Something to look at.

[datsik707]

For the vibration and noises from under the seats, your transmission mount might be shot/gone. Could also be the exhaust banging around if the hangers are loose/broken.

And what do you mean the MAF "looks" good?

No corrosion or any visible signs of damage.

[datsik707]

Center carrier bearing. This will give a vibration about 35 and will cause all the issues stated. They are expensive and most change to a one piece driveshaft.

Number three, check ecu for codes. Just because the light on the dash doesn't come on, doesn't mean the ecu doesn't have a code. Also make sure you plugged in the TPS in correctly. The plug that goes into the front of the TPS can get turned around, causing the issues as well. Something to look at.

Thanks for the advice. As far as the Tps goes, it's been unconnected and put back twice since i've had it. Once to look at it, the other to clean with the electrical cleaner. I doubt that could be it but i'll take a look.

[datsik707]

Alright I'm assuming this is the problem. Thinking of getting the z1 1 piece driveshaft. It will fit with the stock exhaust i'm assuming aye?

[nissanfreak12]

Before you buy the shaft, lift the car up, grab the driveshaft and push up on the shaft, see if there is any movement, generally there should be no movement, if any, its bad. Yes, will fit.

[datsik707]

Yeah I'm going to try and do that tomorrow morning. Already ordered it though so I would need to get it done. If moves I cancel then I'm assuming, fix why loose and go from there

[t.mcginley.jr]

If its loose then you DO need the 1 piece one, if not the that's not your issue but a 1 piece DS still wouldn't be a bad idea anyway. Have you tried another known good MAF yet? And are you sure you don't just have a bad vacuum leak anywhere?

[nissanfreak12]

Have you the ecu for codes?

[datsik707]

If its loose then you DO need the 1 piece one, if not the that's not your issue but a 1 piece DS still wouldn't be a bad idea anyway. Have you tried another known good MAF yet? And are you sure you don't just have a bad vacuum leak anywhere?

What do you mean like buy a new maf? and how would i go about checking for vacuum leaks? Sorry, i'm still learning, lol

[datsik707]

Have you the ecu for codes?

I have not yet, assuming it wouldn't be anything serious though, no check engine light on.

[nissanfreak12]

Just because the check engine light is not on, does not mean it has codes stored. OBD I is notorious for not always illuminating the a CEL when there is a problem. It never hurts to check the ECU for codes, never just rely on the CEL. Who knows, maybe an CTS could be bad causing it to run rich cause it always thinks the engine never warmed up. That will not throw a CEL.

CEL=Check Engine Light

[nissanfreak12]

If its loose then you DO need the 1 piece one, if not the that's not your issue but a 1 piece DS still wouldn't be a bad idea anyway. Have you tried another known good MAF yet? And are you sure you don't just have a bad vacuum leak anywhere?

What do you mean like buy a new maf? and how would i go about checking for vacuum leaks? Sorry, i'm still learning, lol

Checking vacuum leaks is just going through and looking at vacuum lines, cracked lines, bad gaskets. Any of them that have cracks, broken, missing, or you hear a hissing sound from them means you have a vacuum leak. It will cause the problems you have. You can do a boost leak tester, yes I know your car is an NA, still works the same way.

What he means by trying a known good MAF, see if someone around you has a good running Z and swapping it just to check to see if it makes your car run different.

Check for codes first.

[datsik707]

@nissanfreak12
1.Checked for leaks, couldn't find any, no hissing or anything like that.
2. I'll try and see what codes are spat out tomorrow and update from there
3. No known z friends to borrow the MAF, Like you said i'll check the codes before i spend anymore money on fixing it. Besides the 1 piece driveshaft that's in the mail.
@t.mcginley.jr
1. Doesn't feel like it's currently loose, but i'm still behind my idea of spending the extra 150 now for the 1piece.
2. Some exhaust clamps ARE rusted threw, so usless pretty much, but they are not the cause behind the rattling, just something i should get fixed in general.

[datsik707]

Update on possible Maf issue.
1. Noticed just now when idleing, the revbounces between 1.2 and 700. Does not stay in one place, up and down. So i'm leaning towards that vacuum leak more now. Any one else think it's related to the bogging issue? Any other comments and such? Any help is appreciated

[nissanfreak12]

It does sound a vac leak.

[t.mcginley.jr]

You can pick up a boost leak tester for $26 I think from Z1? All you need to use it is an air compressor

[datsik707]

You can pick up a boost leak tester for $26 I think from Z1? All you need to use it is an air compressor

Is there a different device that does the same thing? Trying to see if someone might have one i can use. I guess i need to read up on how it tells you if there is a leak and how to use it. lol

[datsik707]

Also, it idles more inbetween 800-600 or 500 if that makes a difference, when warmed up anyway.

[t.mcginley.jr]

I think you can make your own, I remember reading a write-up about it. Try googling it. It should look like this:

http://www.z1motorsports.com/popup_imag ... imageNum=2

And add a gauge so you know how much psi your putting in (no more than 10psi!)

http://www.z1motorsports.com/popup_imag ... imageNum=1

[datsik707]

Although this may be a good idea and needed. The bogging only happens sometimes, in low rpms while driving. With the idle i don't think it's going to be a leak. Wouldn't i feel loss of power at all times while driving. Maybe idle control valve? tps still? Idk. lol

Now i just got an email saying z1 has to "build" my 1peice shaft, so an extra week. : ((((((

[nissanfreak12]

No, with a vac leak, if its not huge, you will not feel it all the time. It could come and go, sometimes not feel it at all. Did you check for codes yet?

[t.mcginley.jr]

Best bet is to do the boost leak test, you will be able to hear if you have a leak somewhere

[nissanfreak12]

Best bet is to do the boost leak test, you will be able to hear if you have a leak somewhere

NOOOOOO!!!! Codes first, then boost leak, lol.

[t.mcginley.jr]

Ok ok fine lol codes first

[datsik707]

Alright alright, Codes tomorrow. I'll keep you guys updated. Thanks for all the help thusfar. I'll see what happens.

[datsik707]

1 Piece shaft came in from z1 today so i got that in. No more vibrations!!. Got some proper wheels too and their balanced. Rides sweet. No codes today though, I'll throw them up when i get them here this weekend. : ))))

[t.mcginley.jr]

1 Piece shaft came in from z1 today so i got that in. No more vibrations!!. Got some proper wheels too and their balanced. Rides sweet. No codes today though, I'll throw them up when i get them here this weekend. : ))))

Nice!

[datsik707]

Update:codes
43= Throttle Position Sensor circuit says the guide. But it also says my check engine light should be on with it and it's not.
55= None of the above codes.(everything's good)

So obviously the second code interacts with the first one. got 43 once, then 55 came up twice. Sooo, yeah. Any suggestions? heh