Hi!
1)my 94 volvo 940 is reving up.

Normally it revs at 700 - 800 rpm, but, some times, when i am at stop sign or red light,
it revs at 1100 rpm, some time 1800 rpm.
Some times it fluctuates between 1200 and 1900 rpm.

It did not do this a month ago.

Does anybody knows why the car it is doing this?

The car have a check engine light on.
The car is in california and have 155.000 miles.
I bought the car a year ago with 148.000 miles.

2) i am cleaning the inside of the engine with new oil and 1 qt of transmission fluid.
The oil turns black at 700 miles.
Could it be the egr valve is stuck wide open? ... Cel!

Thank you.
Hector.

 

Check the codes first.