I'm baffled

[Shinobi326]

As you can see from my sig, I've only had my M for a short amount of time and have had some significant things replaced under warranty already. In particular I complained of this funny 'jerking' feeling when I drive around 37-38 mph in 5th gear and 1400rpm. The dealer initially thought it was the valve body of the transmission and they replaced it, but that didn't solve it. They then opted to replace the entire transmission. Well, when I was driving home tonight with my wife and hit that magic combo above, not only could I still feel it, my wife noticed it without me even saying anything.

The 'jerking' feeling feels like the car is jerking forward and backward slightly in a pulsing manner. Unfortunately all of the streets around my house are 35 and highly patrolled so I'm always running around 37-38mph.

I'm just hoping that someone can give me some more theories or ideas to chew on so I have more suggestions for the dealership to fix this issue.

[M45Runner]

How about your tire and wheel. If they are out of alignment or balance, it will develop something similar - only at specific speed. So, I would get a 4 wheel alignment and wheel balancing from a reputable shop first.

[Shinobi326]

Hmmm... so this can cause forward/backward jerking? I'm curious what a 4 wheel alignment is? I've never had that on any car before. Does this have to do with the AWD system?

[tytamto]

I know exactly what you are describing, although I never experienced it with my M45. I have had that slight hesitation in my turbocharged cars - a different tune (remapping) always helped.

My wife's stock 3.0T XC60 is doing the same thing. Drives me nuts whenever I drive it. She does not feel it

I wonder if it is possible that your O2 sensor went bad - it might be sending some weird voltage and causing the AFRs to be out of wack at partial throttle. A wideband O2 sensor would be a nice way to see what mixture is being used during this jerking activity.

I wish that we were able data log our cars (at a reasonable cost) and post the logs online for further dissection...

[M45Caliber]

actually sounds like the transmission going into and out of torque converter lock up. Drop it into 2nd or 3rd (or even 4th) gear via the manumatic side and see if you still experience the sensation - my be is you will not. let us know!

[seldomseen]

Damn...you had quite a few issues since owning your Infiniti. I've had the luxury of owning Lexus, Acura and I will admit none of them has as many issues I experienced with my Infiniti---making matters worse is the issues with the Infiniti weren't/aren't minor issues either.

I firmly believe Infiniti's quality/reliability is significantly less than the likes of Lexus and Acura but the price is doesn't reflect so. It's also very evident that common major issues with Infiniti's just carry over from year to year and model to model.

Look into your states lemon law and see if you can dump your M35 now before you end up getting stuck with repair bills costing more than the car's value. No one is going to want to purchase a luxury vehicle that has had so many major repairs performed with under 100k miles.

[M45Caliber]

not the original owner - Lemon Laws do not apply to used vehicles.

[Shinobi326]

Well I'm hoping I can get this corrected before I hit 60k, which is soon. I think this is a solid car (now) since i've had most of the major stuff worked on. When I look at the service history (since all of the service was performed by Infinity, I got a print out since its birth) that there doesn't appear to be any more issues with any system that has been replaced under warranty. So I'm hoping that besides something going wrong with the engine specifically, that I'm pretty much good to go for the long haul (at least 150k+ miles).

So even if this is an O2 sensor or a tire/alignment issue that people have stated before, I consider these fairly minor in nature compared to transmission or engine overhauls.

Any other ideas floating around out there?

[M45Caliber]

before more opinions are offered, di you try driving at that speed in 3rd or 4th gear (not "drive"?). DO that and let us know, OK? good luck.

[Shinobi326]

Yeah I've downshifted to 4 or 3 while doing that speed before and it doesn't exhibit the problem. I think the key is the very low RPMs thus it having to be 5th gear.

[The00Dustin]

I wish that we were able data log our cars (at a reasonable cost) and post the logs online for further dissection...

I have a Car Chip Pro in my 2006 M45 (http://www.carchip.com/Products/8226.asp), it just plugs into the OBDII port and logs whatever you set it to log. I suspect you would consider the cost of one of these reasonable. I actually bought it because it seemed neat and inexpensive; then I ended up using it to log my LTFT and STFT values after someone suggested they might help diagnose an issue I was having in my Park Avenue Ultra. I used it to record benchmarks in my 2006 M45 when I bought it (the car) earlier this year, and I noticed two things:1) The throttle position never goes below 2% in my M45 (asked the dealer about this and he said it was normal as below 2% the engine would die, but in the Park Avenue 0% was idle, as in no additional throttle, presumably just a difference between makes).2) The OBDII MPH record shows ~1MPH lower than the speedometer. I'm not sure the speedometer is right either. I brought this up with my SA, but he said that if the speedometer is within 5% it meets federal standards (and left out any mention of the fact that the OBDII and speedometer don't match).Anyway, I don't know that this is perfectly viable for the M, as mine doesn't log for every trip, as if it sometimes fails to connect, and I don't know if it is loose (there is a crack in it where it holds itself on), or if the vehicle might be an "anamolous vehicle." I haven't talked to anyone at Davis about that possibility, but presumably they would be open to discussion and testing so that this might be possible to resolve (if you were to get one and experience the same issue). My biggest complaint about it would be that it has a pretty small amount of memory, so sometimes if I forget to pull the data off for too long, the oldest of it is overwritten, but it's pretty neat other than that. Anyway, I think I bought it elsewhere for slightly less, maybe <100 USD after shipping, but that's where to read all about it.

[mjlyn]

actually sounds like the transmission going into and out of torque converter lock up. Drop it into 2nd or 3rd (or even 4th) gear via the manumatic side and see if you still experience the sensation - my be is you will not. let us know!

I think M45Caliber is on the right right track.

I experience something similar to what you are describing and after asking for opinions on this forum i'm pretty sure what i feel is the torque converter unlocking.

When i notice what i call a "shudder" is when im cruising in 5th then say i go up an incline that causes the torque converter to unlock. Right when it unlocks i feel the shudder. This only happens on mine if i have been cruising in 5th for a while.

So on yours do you feel it just cruising along. Or is it when there is a change in RPM either from the converter unlocking or an actual gear change?
Modified by mjlyn at 7:38 AM 10/12/2009

[ken in az]

Torque converter doesn't lock 100% till 60mph in any gear.

My bet is the Throttle body is all gunked up and is causing it to stick at very low throttle inputs. My car did that until I cleaned the Throttle Body. Made it go away 95% but it is still there marginally. I think that it is an inherent design flaw because the throttle plate controls idle on this car where most other makes have a separate idle circuit.

be careful if you do decide to clean your TB - I have read stories where damage to the TB itself causes a boatload of problems. As long as you are gentle you shouldn't have any issues.

[nadzak]

I actually had this issue in my G35. Never found out what it was, just returned the lease. But I think it is something to do with the transmission, in my opinion. It doesnt do that in man. mode, and it only did that while trying to figure out whether to stay in fifth, or to downshift into fourth. either a trany/related part or the computer bug...

[szh]

Hmmm ... something to think about ... when I am driving at low speeds (below 40 to 45), in stop and go traffic, or light to light, or climbing long distances at highway speeds (on trips to Tahoe for example), I never keep the car in "D". I always slip it into "M" - the default is Gear 4 max.

(Unlike the newer transmissions, which down-shift this selection as you slow down to a stop, the 2003 M transmission programming just keeps that gear 4 as the "max gear" to select when upshifting. (I have noticed the newer G transmissions do not do this ... they down-shift to a setting of 1 when you come to a stop, so you have to manually upshift again.)

Anyway, this 2003 M setting capability prevents a lot of hunting/shifting for the "right" top gear as I move in traffic, accelerate or slow down, etc.

Sometimes, when I am climbing the hill near my house (fairly long stretch at or about 50mph), I'd rather not have it lug at low rpm, so I set the max gear to 3. Life is a lot less stressful on the car and me, then.

Z

[lovemycarM35]

Has anyone ever experience this on there M35X this has been going on for about year now with my car this is the only thread I found that has the exact thing i'm feeling its only at those speeds and it doesn't do this all the time. I can afford the dealer right now

transmission fluid is clean and full and shift smoothly. The member that started the thread never reported back read the first post i have the exact same issue

[lovemycarM35]

does anyone know if this member is still on the forum

[The00Dustin]

does anyone know if this member is still on the forum

In most forums, you can view a user's most recent posts. This forum is no exception. I clicked on the number of posts under the OP's name, and it appears the most recent post was in 2010, so I would guess no.