2002 Mazda 626 Vibrations

WALTERSAWICKI

MEMBER
2002 MAZDA 626
2.4L
4 CYL
FWD
AUTOMATIC
155,000 MILES

After the transmission was slipping etc, a rebuilt trans was installed, but after it was banging into drive and slipping and vibrating, a 2nd rebuilt trans was installed under warranty, but this one has caused major vibrations in gear, or neutral, or park at 750 rpm idle. When boosted to 1,000 rpm, the vibrations disappear. Mazda service advises they cannot boost the idle due to factory settings. It is even worse when the A/C is on as the idle drops unlike my Miata where the idle increases when the A/C is on. Motor and trans mounts and the idle air control valve have all been replaced w/ no effect. Is there a way to change these settings, or place something on the accelerator like a govenor to prevent it from going below 1,000 rpm? I recognize that the torque converter may be defective, but I do not want to spend any more money on the trans.

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,772 POSTS

There is no way to change the idle speed. It is controlled by the computer. However, the IAC should increase the speed when the AC is on. Are you sure there is power to the IAC?

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Thursday, January 15th, 2015 AT 5:26 AM

WALTERSAWICKI

MEMBER
3 POSTS

Not sure, I will have to check it out.

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Thursday, January 15th, 2015 AT 9:06 AM

JACOBANDNICKOLAS

MECHANIC
109,772 POSTS

Let me know. If there is no power, the IAC is doing nothing, which would cause the problem.

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Thursday, January 15th, 2015 AT 11:02 AM

WALTERSAWICKI

MEMBER
3 POSTS

I will be scheduling to replace front struts on this car. At that time, I will ask them to check the power to the IAC. Even though the the idle speed is controlled by the computer, can some sort of mechanical govenor for lack of a better term be placed on the accelerator pedal so that it starts from zero a little below its normal setting so that at idle, the rpm is around 1,000? I am not concerned by additional use of gasoline and it probably might not increase gas costs significantly. Any thoughts on that?

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Friday, January 16th, 2015 AT 11:50 AM

JACOBANDNICKOLAS

MECHANIC
109,772 POSTS

I wish it was that simple. However, no it can't be added. Chances are either the sensor itself is bad or there is a power supply problem between it and the PCM.