Help: Check engine light on, code 71 Options

[Jules88]

Hi, I have a '94 Celica ST automatic, with about 170,000 miles. The check engine light is on and it's code 71. I already cleaned out the EGR, but the check engine light came back on after I reset it. So I got another EGR used from Pick a Part, and the light is back on again. Could it just be it needs a new sensor?
Also, smoke comes out of the tail pipe when I give it gas, and it smells really bad. Is it unrelated to the check engine light being on? I've considered having the engine rebuilt, but I want to make sure before I spend that much money. It has good compression. I bought valve seals but the person who was going to do them said it would be best to just rebuild the engine. And the person I bought the car from said he recently rebuilt the engine. So I just don't know..
I'd appreciate any ideas on these problems. Thank you!

[Box]

Also on the other issue. Is the smoke blue or black, and does it smell of fuel or oil? The 7A-FE is notorious for stuck oil rings that'll let oil into the combustion chamber and will cause burn off. Not too big an issue as long as you keep oil in it. You can try doing piston soaks and running detergents through it in hopes of alleviating the problem by breaking the rings free. I was lucky and was able to break my rings free by running Marvel Mystery Oil in the crankcase, and doing a piston soak with the Marvel.

[Jules88]

Thanks for the advice. The smoke is gray, and there is a lot of it everytime I accelerate. People are saying it's oil. If that's the case all I have to do is use that Marvel oil you mentioned? Because they are trying to get me to rebuild the engine, and I really don't want to do that.
Thanks again.