A strange sound

[PROTEUS]

My Xplo began to do a rhythmic sound, the motor sounds ascending and descending its intensity. It's not constant!!. It is even the speed selector is in Parking and Drive, just not in Neutral.

I don't know what can it be...fault in the motor?
fault in the tranny?

Does anyone have an idea???

it is something like this:

ruum RUUM ruum RUUM ruum RUUM ruum

 

[jimbo74]

mine was a dirty air filter and maf.....did the same thing when i went wheeling.....

 

[88vert]

I agree with Jim Check mas and tps,and iac

 

[PROTEUS]

Uh! what curious!! I cleaned the MAS three days ago and the motor still sounds increasing and decreasing the load.
I shall check the air filter and TPS...but what means IAC???

 

[88vert]

iac

Idle air control valve