Vibration, shudder, rumble at low RPM in 4th and 5th gear

chance-ihs

Member
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Mazda CX-9 GT
When at low RPM usually between 1300 and 1700 RPM in 4th or 5th gear I get a bucking vibration or shudder. It completely goes away when I give it more throttle or less throttle or switch the transmission into manual mode. It does not happen when accelerating more aggressively or in manual mode. It is a 2008 CX-9 Grand Touring AWD with 95,000 miles on it. The manual mode absence of this problem makes me think that it is related to the torque converter locking and unlocking. What regulates that? Does anyone have any idea what could be causing this problem? Thank you, Chance
 
BTW, a year ago the drive shaft was replaced when the carrier bearing failed and I recently replaced all of the plugs and coils in an attempt to solve the problem.
 
BTW, a year ago the drive shaft was replaced when the carrier bearing failed and I recently replaced all of the plugs and coils in an attempt to solve the problem.

pretty high AWD mileage at 95,000, did you service the AWD transfer case ? worth a shot, give it try, pretty easy process and only $10 worth of 75W150 oil......
 
No, I have not serviced the transfer case. It is worth doing but I don't see how that could be the source of the problem with the symptoms described...
 
Sounds exactly like the spark plug/coil issue mentioned in multiple threads. Are you sure you didn't get a defective plug/coil ? Did you replace all the coils ? Was there any change at all ?
 
My '08 GT AWD does exactly the same thing - right at 1250 rpm and does not slip/buck when I switch to manual. I had a mechanic friend put an OBD reader on it and found no codes whatsoever. I've looked at a lot of posts on similar symptoms, but cannot decide on a starting point to look into myself. I did pull the AT dipstick and I have a question for the group: What color is your ATF and which brand and P/N do you use? My fluid is grey in color and my manual says that it should be JWS3900, which some info shows that this is an equivalent of T-IV. Again, I've looked into a number of posts here and other sites, and cannot seem to get a straight answer or consensus on what to use. I want to top it off to see if the slip goes away, but can't seem to find this grey ATF, only the typical pink in color - like a Castrol Transmax, that I grabbed from Autozone. Anyone have any other input to share? I want to troubleshoot to a certain extent, before spending $120 on 8 qts. of this Mazda JWS3900 from Amazon - which consequently, isn't even 'recommended' to fit my 2008 CX-9 GT AWD, according to Amazon. Their site leads me to the T-IV.
Any info would be appreciated!
 
The JWS3309 and the T-IV are the same fluid. The color is red. You can get Toyota T-IV for around 6 to 7 bucks at the dealer and cheaper online. Look at ebay. You can get 12Qts of T-IV for around 70 to 80 bucks shipping included.
 
We had the same issue with the shuddering as if you were driving slowly over the "rumble strips" on the side of roads. Fourth gear, 1900 rpm and very light throttle would produce a three second shudder. So fast that we didn't have time to drop it down into manual mode to isolate the noise. We drove it like that for 5000 miles and it kept getting more and more prevalent. I replaced all the coils and plugs. No dice, still did it. Replaced the fluid at the dealership, still shuddered.

Turns out at 87,000 miles the torque converter was bad. Dealership wanted $3,700 for just the converter and labor or $5,000 for a reman. unit. Local tranny shop replaced the transmission with a used one that had 22,000 on it for $2,500 and no more shudder. Before all this started, we had a local mechanic flush the fluid prior but used a "universal" fluid instead of the STRICTLY recommended Mazda/Toyo fluid.. The tranny shop and dealership both agreed that the incorrect fluid did it in. The mechanic is a friend and since we had driven almost 12000 miles since the flush we didn't have any recourse.
 
Cx9 vibrations in 4th

We had the same issue with the shuddering as if you were driving slowly over the "rumble strips" on the side of roads. Fourth gear, 1900 rpm and very light throttle would produce a three second shudder. So fast that we didn't have time to drop it down into manual mode to isolate the noise. We drove it like that for 5000 miles and it kept getting more and more prevalent. I replaced all the coils and plugs. No dice, still did it. Replaced the fluid at the dealership, still shuddered.

Turns out at 87,000 miles the torque converter was bad. Dealership wanted $3,700 for just the converter and labor or $5,000 for a reman. unit. Local tranny shop replaced the transmission with a used one that had 22,000 on it for $2,500 and no more shudder. Before all this started, we had a local mechanic flush the fluid prior but used a "universal" fluid instead of the STRICTLY recommended Mazda/Toyo fluid.. The tranny shop and dealership both agreed that the incorrect fluid did it in. The mechanic is a friend and since we had driven almost 12000 miles since the flush we didn't have any recourse.
 
I have the same issue with my 2011 AWD with 95k miles. Mazda replaces the transfer case three times (got to something else). I also replaced the rear hub control arms and rear assembly mounts, rubber was either missing or really cracked. I also replaced the lower engine mount bc of cracks. Vibration still there. Mazda says trans is good. Comments? I still think theres another bushing somewhere that bad.
 
2008. Cx9

Same issue here too. Been told it was mainly the bushings on the rear subframe and also bent center support. Many other threads also say bushings and that has been the fix for quite a few of the posters. Cheap fix if you can do yourself. I cannot. Mazda wants to replace the entire subframe... Go figure. Nice car but had a lot of issues. So far engine and trans are good.
 
Same issue here too. Been told it was mainly the bushings on the rear subframe and also bent center support. Many other threads also say bushings and that has been the fix for quite a few of the posters. Cheap fix if you can do yourself. I cannot. Mazda wants to replace the entire subframe... Go figure. Nice car but had a lot of issues. So far engine and trans are good.

I have the same exact problem if using manual shifting stops the shuddering then it is the ATF modtly the torque converter, in my case to be more sure I used instant shudder fix lube gard and it fixed it for a week or so then I did add it once more this week and will see how it goes, I did this after changing the ATF fluid
 
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