Help M56S MAJOR PROBLEM

[a_dahlan]

I just bought a new M56s couple of months ago . I started experiencing a problem at 1000 Miles , When the car is on 1st gear and i start stepping on the gas i hear a knocking noise . It feels like something is hitting especially under the area of the arm-rest . The problem is that , the noise is not constant . It appears every once and awhile. I took the car to the dealer , the kept it for a week and then they told me , the transmission mount was loose and we replaced it . Now at 2500 miles , the sound is appearing again . Is anyone experiencing the same problem ?

[FNAWSM]

unfortunately you are one of the few that have the new m56 so it may take a little while for you to get your answer. Most of us here have the m35/45 but slowly we are getting more M37 and M56 owners joining. I hope you get an answer soon and if you figure out what your problem is please update us here so it will help others in the future. Welcome to the forum!

[a_dahlan]

Yes , the car was checked by the dealer . They informed me that the transmission mount was loose and therefore, they have replaced it . However, the noise still appear every once and awhile . It feels as if something is impacting underneath the arm-rest. My assumption is a drive shaft problem . I have an appointment for next week , I will post all the updates once I have any.

[DougC]

I purchased my M56 (non-S model) in Dec. 2010 and have had my challenges since. But no, no knocking noise at any time. The closest I can come is that when I'm almost stopped preparing to back into a parking spot, the car clunks when I slip it into neutral...which doesn't seem too odd or problematic to me. My remaining problem is that sometimes (like your problem, not always) I have a very noticeable low speed (1200 to 1500 rpm) engine shudder as I drive. The dealer says he can't feel it, and tires have been checked as perfect in every way (Michelin still offered free replacement of all (4) !). I can live with it, it's just really pathetic that a $60k car misbehaves like this. Reminds me of my 1969 Charger 440 at idle. Good luck with your knocking !

[lovemycarM35]

I purchased my M56 (non-S model) in Dec. 2010 and have had my challenges since. But no, no knocking noise at any time. The closest I can come is that when I'm almost stopped preparing to back into a parking spot, the car clunks when I slip it into neutral...which doesn't seem too odd or problematic to me. My remaining problem is that sometimes (like your problem, not always) I have a very noticeable low speed (1200 to 1500 rpm) engine shudder as I drive. The dealer says he can't feel it, and tires have been checked as perfect in every way (Michelin still offered free replacement of all (4) !). I can live with it, it's just really pathetic that a $60k car misbehaves like this. Reminds me of my 1969 Charger 440 at idle. Good luck with your knocking !

Can tell me what engine shutter? is please

[DougC]

By engine shudder I mean a very low frequency shaking, somewhat irregular in frequency. It can come from an irregular cylinder misfire, or a faulty active engine mount, or probably other causes that I'm not familiar with. It feels like someone is giving the engine a sideways shove by hand. It only happens perhaps 10% of the time while driving with the engine at 1200 to 1500 rpm.

[a_dahlan]

Think you for sharing your problem with us . I suggest that you check the air mass sensor . I had that problem once with my lexus gx460 . It was raining heavily and after the rain within couple of days , the car started shacking at low rpm . I plugged in a general diagnostic device than you can purchase from ebay and it showed the fault . I took it to the dealer and they replaced it , now the car is perfect.

[The00Dustin]

By engine shudder I mean a very low frequency shaking, somewhat irregular in frequency. It can come from an irregular cylinder misfire, or a faulty active engine mount, or probably other causes that I'm not familiar with. It feels like someone is giving the engine a sideways shove by hand. It only happens perhaps 10% of the time while driving with the engine at 1200 to 1500 rpm.

My 2006 M45 does the same thing at similar RPMs when climbing a "hill" (on the off chance that I can get it to do so at such low RPMS). I never really thought much of it, but maybe Nissan's engines are just really underpowered at that low of an RPM range.

[DougC]

Hey guys, thanks for the feedback. I have to park the car today for a few weeks, but when I'm back I'm going to ask the dealer to check that air mass sensor. The fault code should still show up. I also appreciate the comment about an M45 having some shudder at low rpm's. I think that with the low-rev-type gearing in the car (for the sake of gas mileage I'm sure) the vibration I feel might just be a bit of low rpm overload on the motor, though I feel it most on cruise control on level road at 45 mph ! Anyway, thanks again for the suggestions. Doug

[Pimperish1]

I wish I could be of more help man but just for the purpose of polling regarding your problem I must say I have never experienced that. I'll be back if I do though.

[slachance]

Hey guys, thanks for the feedback. I have to park the car today for a few weeks, but when I'm back I'm going to ask the dealer to check that air mass sensor. The fault code should still show up. I also appreciate the comment about an M45 having some shudder at low rpm's. I think that with the low-rev-type gearing in the car (for the sake of gas mileage I'm sure) the vibration I feel might just be a bit of low rpm overload on the motor, though I feel it most on cruise control on level road at 45 mph ! Anyway, thanks again for the suggestions. Doug

I think I know what you're talking about, but I agree with your assessment that it's caused by low rpm gearing to save fuel.. I notice it occasionally when driving very conservatively.. Can't say it bothers me though.. Guess I tend to get more irritated by things like squeaks and rattles... There's also the occasional 1-2sec hesitation in the transmission when taking off from a complete stop. ..Still hoping for a new TSB to resolve that one.

[K_350gt]

I just bought a new M56s couple of months ago . I started experiencing a problem at 1000 Miles , When the car is on 1st gear and i start stepping on the gas i hear a knocking noise . It feels like something is hitting especially under the area of the arm-rest . The problem is that , the noise is not constant . It appears every once and awhile. I took the car to the dealer , the kept it for a week and then they told me , the transmission mount was loose and we replaced it . Now at 2500 miles , the sound is appearing again . Is anyone experiencing the same problem ?

I sort of have the same problem in my 2004 Nissan Fuga/infinity m35. Every time i switch the car on and right when the gear changes to the second gear, there is this knocking sound, like a push or something falls of from the engine side. i don't know if its the same as yours, but this is really annoying. Also, a rattling sound every time i hit the pedal at a low speed with low Rpms. I can relate this to you.