Shaking at 40 MPH

[Infinitiguy19]

When I was driving home today I had the cruse control on and and I went 35-40 by pushing the resume accerlation button. And while holding that button I noticed the car started to shake really bad I mean really bad (the whole car was going back and forth.

Also when the ignition is on and I press the gas say half throttle there is a buzzing noice that comes from the engine?

I got a used MAF (To replace what I think was a bad one)

Checked all 8 injectors and came back fine

Engine and Transmission mounts replace about 50,000 Miles ago. (Not sure about the drive shaft but I beleive I would fell shackiness at a higher speed which I dont.)

Throttle position sensor is at 2% when throttle is closed and pedal is untouched and the Min is .58 volts and max is 4.30 volts.

IAC is at 10% duty cycle

Fixed the MAF connector

The Idle was adjusted from the throttle body (one day the car started to shake really bad when I started it up I thought I lost an injector turned out to be the MAF but the crappy mechanic I took it too adjusted the Idle throw a little screw on the Throttle body.)
Modified by ppastos at 10:09 PM 9/3/2008

[maxnix]

50K and the 3rd motor (transmission) mount is probably shot, especially if it is 5+ years old.

Better take your car to someone who at least can read the FSM.

[Infinitiguy19]

But I tried several times to recreate it and couldnt it only happens sometimes not every time I go to 40MPH

In order to recrate the problem I have to acclerate to 40 MPH very slowly

anyway to check the transmission mounts? Is it simmilar to the way you check the engine mounts?

[qship96]

transmission torque converter lockup problem?

[3Q Jay]

i think qship is on to it.if you are in 4 lockup and press gently, it will lug and struggle.try putting the selector in 3 (or even 2!!) and trying your same test again with the cruise control.

PS- adjusting idle speed at tb is bad, very bad.

[maxnix]

To add further (and there are many previous discussions of lugging in D), accelerating in D up a hill or from very low speed will cause the lock up clutch to chatter, especially if the intake path is not up to as new cleanliness standards.

The TB adjustment needs to be undone properly.

[Infinitiguy19]

Sorry I forgot to mention this I threw in a bottle of ISO-Heet and I think that may have been what was causeing it but there was no shaking at any other speed just when I had cruise control and and press the resume accleration button.

I also checked the transmission fluid and it is red but a tiny bit dark and I will be adding a transmission cooler this saturday for sure.

[maxnix]

If it fails the white paper towel test in any way, time to mechanically exchange it. Add the ATF cooler then.

[jerdog1]

Its ur driveshaft!Junk yard 100$ DONE!!!

[Infinitiguy19]

Would it matter if I added the cooler before exchange?

Or is it just easier to do since its on the lift?

[qship96]

iso-heet,nor the transmission fluid/cooler is the cause of your problem.

As far as buying a driveshaft from the boneyard....dont! It will probobly be in same/worse condition than the one you have{which also is not causing the symptoms you describe}

Look to either transmission problems{lockup torque converter/control} or engine drivability issues{maf,misfire,dirty intake path/misadjusted control parameters}.....my money goes on transmission problem

[maxnix]

Its ur driveshaft!Junk yard 100$ DONE!!!

The foam inside the driveshaft is what detiorates, sending them out of balance.

[Infinitiguy19]

Is there a solid Driveshaft or even a carbon fiber drive shaft that would solve the out of balance problem?

[goody90q45]

.....Look to either transmission problems{lockup torque converter/control} or engine drivability issues{maf,misfire,dirty intake path/misadjusted control parameters}.....my money goes on transmission problem

I have TC shudder in my 90Q at 35mph, 45mph and 55mph. It's more of an annoyance since the transmission shifts fine under moderate acceleration. None of the shuddering is in the 2200 rpm range which is a vibration you'd feel if it was a worn transmission mount. A transmission flush/ filter change and a couple treatments with Lucas got rid of the 35mph shudder and improved the 45 and 55mph shudders.

What is the fix for a worn TC? Replacement? Adjustment?

[maxnix]

I have TC shudder in my 90Q at 35mph, 45mph and 55mph.

In which gears?

Lucas, I don't know....

[qship96]

Try adding 1oz at a time of lubegard BLACK to modify the slip/stick ratios of the atf, could help or even eliminate all the shuddering.

[kdkrone]

Like jerdog1 says, check your driveshaft/universal joints. I had a similar problem on my 92 Q at 35 mph.

KK

[Infinitiguy19]

The problem is virtually gone I mean there is a tiny bit of torque converter chatter but I hope the transmission cooler solves this which is going in first thing tommorow.

Down the line in about a months time I will flush the transmission.

And then see if that helps if not I will do the mount.

And then maybe if its the drive shaft (Crossing my fingers its not) I will obviously have to do that.

[maxnix]

White paper towel test? So easy to perform!

An ATF cooler with degraded ATF will not help your car.

[SteveTheTech]

It definitely sounds like your TCC is not disengaging when it should using the cruise input. The ASCD system is consult compatible you may want to think of getting it looked at at the dealer, as most of the related parts are not cheap.

ASCD control unit and/or AT assy are both in excess of a grand.

The torgue converter clutch engages at speed greater than ~35+ with throttle input <1/16 application. I cannot find the information saying which TPS controls TCC operation while using cruise but there is an input signal from the TCC control unit to the ASCD control unit. According to the FSM the TPS should be adjusted using resistance value are those the numbers your talking about? http://www.nicoclub.com/FSM/Q4...c.pdf EC-219 this is the component.(I am not sure that they are the same but that's the oldest one I could find)

I have also seen a few transmissions be damaged from reverse flushing . In some cases if the varnish is removed from your clutch packs the gap increases to an excessive level where they will slip. I agree with Maxnix do paper towel test before anything.

[Q45tech]

Hard to make a 15 year old transmission/TC act like a brand new unit too much wear and tear and prior abuse even at 113k.

I have never been satisfied with even a 7 year old transmission [but I drive many more interstate miles annually]. Why I am on number 3 now [6 years old + 90k] and expect that one to only last another few years.

These transmissions are near their absolute limits as to torque [ 300 lb/ft] vs the newer 5 speeds at 333 lb/ft.

Don't spend too much time chasing wild geese, just secure a Nissan remanned and swap

I had the cruse control on and and I went 35-40

Cruise control should not be used slower than 55mph!!!!!!!!!!

[Infinitiguy19]

Why shouldnt cruise control be used below 55MPH?

[maxnix]

For one thing, you should not even be in D below 55 mph unless you are coasting downhill.

[Infinitiguy19]

Well ok then 3 is good till 55 MPH you say?

Wes says keep it till 40 then go to D.

[SteveTheTech]

I am at a loss to figure this out though. I understand the logic with an older car (my father was hard core with the not driving with OD on) but even the 94 Q used a duty cycling TCC. I unfortunately don't own a classic Q does it make a difference in the long term performance of the trans?

While cruising around in third you are running your overrun clutch continuously that and the TCC are both sort of wearing parts in a similar way. At least the TCC will save fuel mileage.

[bullittandy]

Try adding 1oz at a time of lubegard BLACK to modify the slip/stick ratios of the atf, could help or even eliminate all the shuddering.

Lubegard BLACK is not reccommended for Nissan trannys.

[qship96]

Not in correctly operating as new trannys maybe, but in old worn transmission with problems it sometimes buys you some time by altering slip/stick properties of atf. to compensate for problems.

[Q45tech]

Depends on your technological skill and knowledge of tribology. A small amount of BLACK can be mixed with RED to fine tune the single lockup clutch wear and tear. The newer 5 speed has a dual lockup clutch and the newer SPECIAL ATF has some of the stick-slip characteristics of the BLACK so the converse is possible using mostly BLACK with a little RED.

The nice thing is if you make a mistake you can drain and start over............not like either will cause an instant failure.

When a transmission has 100k or 7 years time to get scientific and educated if you want to squeeze every single mile out of it.

As to using 4th at low speed the engine doesn't produce much torque under 1800 rpm [54 mph] and that torque is reduced by [0.694 gear] by 30%....................forcing TC to unlock/lock/unlock/lock is stressful especially when engine is not up to par as most 100k engines are.

45 mph is the absolute MINIMUM test speed [see FSM] for in warranty systems not old abused systems why I feel 50-55 mph is the slowest speed usuable [of course depending on road slope].

[Infinitiguy19]

Just Installed the transmission cooler and its like the transmission is healing its self. I have better, faster smother shifts. but the problem problem is somewhat fixed except for idle which I forgot to mention is where the problem also existed.

When I rev the car in park to 1000-2000 RPMs the car shakes a bit almost like it has a HEMI but it also does it when driving too (at 40 MPH in drive and the RPMS are around there that range which is another clue).

Don't think this is a transmission issue anymore could it be an injector?

[maxnix]

Yes, or a motor mount (how much does the engin rotate?), coilpack, plug.....