92 Q45 vibration

[bbdaines]

Good Afternoon,

I am new to this, and have been reading through thread for hours. I have not seen anything specific to the problems on my 92 Q, 144k. I don't know much history on the car, I bought her at auction with a salvage title! (cheap, maybe).

1, the trans was rebuilt by aamco in 2000, and a cooler installed, it will not shift into 4th. The trans seems to run and shift fine beyond not going into 4th. I had a shop check it and they told me that all the external was fine and thought it must be the valve body.

2, the car has a vibration from maybe 1200 to 15 to 2000 rpm, having read a bunch of threads, it sounds like exhaust, transmission or engine mounts. The vibration does not change if the car is in park drive, reverse or nuetral and does it through the gears. ??

I have had the A/C serviced, trans flushed and will change the trans filter in a minute when it cools off outside. I changed the spark plugs, the old were fine but I wanted to see each one.. they all look good and I have put a fuel filter in. I really thought the vibration was a miss, but don't think so anymore?? and the vibration goes away at higher rpm?

You guys obviosly know these cars, it is alota fun to drive this car, it handles way better than a BMW 540i I bought.

Anyway, thanks for any suggestions you may have.

Blair

[90Q45blue]

Hi and welcome to NICO!

1a. Transmission - the fact that they installed a cooler is good, but they obviously did a piss-poor job of rebuilding the transmission if it's broken in only 4 years. You could try a transmission flush with MOBIL 1 ATF and replace the filter and see if that cleans out any gunk, but that's probably not what the problem is.

1b. You should check on AAMCO's warranty policy, but my guess is you're SOL. Your best bet would be to get a remanned transmission from Joe @ Everything Infiniti. They will also give you a $400 credit if you ship the old core back to them.

2. Vibration - I'm thinking the transmission and engine mounts need to be replaced. The transmission mount would be perfect to do if/when you get a new transmission. The engine mounts aren't too expensive either. Any one of our Infiniti sponsors to the left will give you a good price.

Hope that helps. Others will chime in shortly. Welcome to NICO

Nick

[texasoil]

Vibration with the car not moving is always related to engine and not the driveline. For the 90-93 Q45's, its a combination of exhaust system resonance, car body resonance right at the rear of the front seat tracks, sagged transmission mount hitting the crossmember, hardened exhaust system rubber hangers, and old engine mounts.

[bbdaines]

Oh my, do I feel lucky with this one, the car still vibrates, but the transmission is working!! I mentioned that I had the trans flushed, and tonite I dropped the pan to replace the filter, well it was really pretty clean, a few shavings, except for a bolt attached to the magnet!! Crawled under the dripping valve body and found where it went to hold a Solenoid, at least it looked like one. Well, the bolt that holds the ground wire was lose also. I tighten it all up and put it back together, added the ATF and it works!!!

Thanks to both of you for the replies... is there a thread or how too on the mounts??

Thanks Again, Blair

PS. is there a good explanation for the starting in 2nd gear??

[Q451990]

90-92Qs started in 2nd gear to increase fuel economy and driving comfort. Many BMW and other high end models of the same era had the same "feature." So at this point you're running with a 2 speed transmission!

The vibration you mentioned... is it more of a "bouncing" at idle? That would indicate a dead miss on one cylinder (typically an injector failure).

Welcome to NICO!

Heath

[bbdaines]

Hi, The car does not vibrate at idle, it starts at about 1200 rpm and goes to 2000 rpm and gets better but does not go away until the engine is over 3000 rpm.

Now that 4th gear is working the car runs at the top end of the vibration range on the road and it comes up through the steering wheel. I have run a can of Chevron fuel additive through her, and finally found a store that carries BG44k and added it tonite, but have only driven to diner, 5 miles. Hope that helps, but am really thinking it is the mounts.

Thanks, Blair

[90Q45blue]

They also had the early Q's start in 2nd gear because they did not think it fitting for a luxury car to do burnouts.

Glad to hear you transmission is working. So from what I understand from your previous post it is missing a solenoid? I would get that fixed to make sure this doesn't happen again...or worse.

As far as the vibration, it's sounding to me more and more like one of 3 things: a MAF that needs replacing or re-wiring, a bad transmission mount, or bad engine mounts.

Nick

[bbdaines]

Hi, I went back and read my post, not to clear... the solenoid was in place, one of the bolts had come out, and the others were lose. 1 of the bolts holds a ground wire and since it was lose, it wasn;t grounding...

This car is incedable in the twisties, it drives like a sports car on rails.. really fun if I just get it running really right!!

Thaks Agian, Blair

[maxnix]

I wonder if the transmission was "rebuilt" in its earlier life?

[Q451990]

the trans was rebuilt by aamco in 2000

[texasoil]

Once again the 'vibration' you describe is due to resonance. A sagged transmission mount will let the transmission just touch the crossmember and will cause the vibration to grow until you feel it. Also, the exhause hangers at the rear of the transmission get hard with age and stiffen the system enough that it also begin to resonate (vibrate) in the same frequency--leading to vibrations you feel.

[maxnix]

As a matter of fact, I faintly recall a TSB on this for the early Q45. Mentioned the exhaust hangers also.

[bbdaines]

Hello,

So, I still have a vibration, took the car into a service center and had it up on a rack. Can;t tell anything about the engine mounts but the transmission and exhaust all look fine with the car running. I read in another thread how it feels coming up through the steering wheel if you have a bad injector, but you feel the vibration worse at idle, mine has no vibration at idle... but it comes up through the steering coumn just as decscribed. I read in post that the first thing to do, before pulling injectors is to run BK44 through the system for 3 tanks, I am half way through the first tank and believe it is working, it's still there but seems less!!

This forum is great, i was doing the searches wrong and not getting to al the threads, lots of info on the Q!!

Thanks, Blair

[texasoil]

Why do people want an exotic problem to fix?

The vibration you are feeling is not injector related. You cannot 'see' the transmission mount problem. If you have not replaced the transmission mount--that is the FIRST thing to fix.

Check the engine mounts by--hood open, in forward, brakes applied slowly add throttle and observe engine movement. Same in reverse. Bad mounts will allow engine tomove a lot instead of an inch or so, and the movement will be abrupt rather than gradual extension of the rubber.