I have not driven my 89 IROC very much in the past couple of years, lately I have been driving the car and I had a few questions.

I bought this car and had some tranny issues it is a 350 TPI car with a 700R4 auto, rebuilt it twice. Now it dos have a small leak but my question is with the convertor. When I drive this car I am pushing 3000 RPM at 60 mph. is that normal? It seems to go into the gears a bit weak in my eyes, but it does go without slip. When I am finally in overdrive the convertor should lock up correct? Then I should lose some rpm's. I lose about 100 rpm's? I was told I should lose about 500.

Also when I keep it floored it does not want to go into overdrive unless if I let go of the throttle, so I do that, but as soon as I hammer on it again it kicks out. What is the malfunction there? Keep in mind that this is around 95mph which is now about all the faster I will go since it fights staying in overdrive. When I bought the car 2nd and 3rd were weak but I could get 130 pretty easily.

Ideas?
Thanks
Chris

 

Are you sure your tach is accurate?

About 100 RPM is pretty normal.

There's no malfunction, it's designed that way. Overdrive is for cruising, not accelerating.

 

My tach could be off but I do stop at the pumps frequently.

The100rpm is normal, well that helps since I was worried about that.

As far as how it runs now vs before when I try to go fast, I can't. Before I could, I could keep her floored and get up to 130 or so, now I can't. Could this also be a bad TPS sensor????

 

There are no sensors that affect the shifting of the transmission.

 

are you still using the stock converter?

 

yes I am still using a stock convertor. New obviously, not the original one

 

That sounds like way too much rpm to me. I would only expect around 2000rpm even if it had some decent gears. If that's really the rpm it's turning at that speed, it is likely not in overdrive and not locking the converter. Maybe you could check if it locks up. If the car's going 45mph or more, you should be able to give it a light increase in throttle and have basically no rpm increase until the car speeds up. If the rpms pick up the instant you start applying some thottle, the converter is not locked.