I have an 07 Mazda 3 Neo 2.0 Automatic with about 90000kms on the clock.

Recently the car has decided to have a bit of a shudder after coming to a stop whilst the car is in drive - similar to what you experienced on older cars when you put the a/c on whilst at a stop.

There does not appear to be any idle seeking, the revs don't fluctuate and there is no codes thrown.

I have also checked the engine mounts which all seem to be in excellent condition.

So far I have cleaned the MAF, inspected the air intake system including throttle body and flushed the transmission fluid, all to no real improvement. I also removed and cleaned one of the solenoids that some people have problems with, but I expected it to throw a code if this was the issue.

Any suggestions as to what else could be the cause of the problem?

 

Vacuum issues? Check spark plugs/coil? no mis-firing issues? I know the TPS in the throttle body can cause similar issues and not throw a code yet.


Symptoms of a Bad Throttle Position Sensor
Modern vehicles feature sophisticated computer-controlled engine systems. These systems, however, can only perform as well as the data fed them by their electronic sensors. The throttle position sensor helps the engine set the correct fuel mixture for the vehicle from moment to moment, and if this sensor malfunctions, the car can experience a host of problems, such as stalling, rough idling and lackluster engine performance.
Things to consider.

https://www.mazda3club.com/mazda3-mazdaspeed3-99/p0507-issue-trying-resolve-57929/

~Mud

 

I replaced spark plugs today, inspected coils and cleaned contacts, and performed the coil spring stretch mod common for mazdas. No difference.

Old spark plugs were generally what you would expect from 80thou km old sparkplugs ... no oil or tell tale signs of rich or lean conditions. They were quite clean all things considering.

I also reset the ecu, have taken it for a drive and checked codes ... still nothing. No misfires have been detected either.

I did a quick 30 second rpm plot, the large jumps correspond to the 'shudder' but at the end of the day we are only talking a 5% difference in rpm.



Another thing to note - I can hear a noise at around 1300-1500 rpm, but nothing outside of this range. Noise is coming from the belt side of the engine (Drivers side in my RHD car) ... I would describe it as a rattling / loose bearing kind of noise but it ONLY occurs in this rev range.

Can you get a replacement TPS? I had a quick look and all I could find was replacement throttle bodies with the TPS installed, which were quite pricey.

 

any chance you could have someone rev for you and track down the sound around the pulleys with a stethoscope? While I don't know it would cause a shuddering it's possible one of the pulleys is having issues and causing the noise.