can anyone help? i have a 93 silver rx7 54k miles when it is in idle the tach goes up and down(from 2k to about 250 rpms) when i accelerate it is very rough and the tacj stil goes up and down even while accelerating when i looked at the smoke it was blackish and i looked at it a while ago and it was whitish anyone that has an educated clue plz PM me thanx

 

Check to see if a hose has blown off you MAP (Manifold Absolute Pressure) sensor.

 

where is that located?

i just put a boost guage on it

 

it's located on the driver side firewall and has a single hose which goes to the side of the throttle body/upper intake manifold area.