I desperately need some help diagnosing a problem that could be very expensive, or could be very cheap and easy.

I drive a stock 89 Camaro RS with 305 TBI and 700R4. She's got 215K miles, and neither the engine nor the tranny has been rebuilt.

My tach shows that my engine is running much higher RPMs than it should. In fact, it runs too high, consistently, ALL THE TIME:
- cruising in 4th gear is too high (2200rpm at 60mph, used to be 1500rpm at 60mph),
- all the shift points are too high (shifts now at ~5500rpm, used to be 4250 on the nose)
- idle is way too high (1500rpm, used to be <500)

I have verified that the tach is right, because my fuel economy has gone down to match. (My mileage was 3/4 what it should be, when my cruising RPM was 4/3 what it should be.)

The tranny still functions like new: shifts as smooth as ever, no momentary spin-up, no weird sounds, good acceleration. Everything is great. It does leak fluid all around the pan, maybe a quart per month or two.

I've been ignoring this problem for about a year because it's so slight, but in the past few months, it's gotten much worse (see above).

Is my tranny gone? What do you suggest I check first?

 

I'd bet money the tach is off, if I was the betting kind. The thing they put in your dash is not an instrument, at all; it's just there for looks. Especially in a TBI auto car. As far as the factory was concerned, it's just trim, designed to add to the sporty "image" of a car that has no need for the driver to be aware of actual engine RPM. Don't assume it's right, because it probably isn't, and never has been, and it's just getting worse to the point that you're noticing it.

Take the car to a place that can do real tune-ups; somebody with an actual test equipment setup, in other words. Have the tach checked against an instrument.

These cars' tachs are almost always wrong. They fail by reading high, and they tend to read higher and higher as they fail more and more.

You might want to get a new O2 sensor installed while the car is getting the accuracy of its "interior trim package" checked, if you haven't done it lately; that's a frequent cause of poor gas mileage.

 

Welcome to thirdgen.org.

If after you verify the tach reading and it is indeed higher, first thing I'd do is have the TV cable adjusted, you can find the "how to" in the tech section on the main page of www.thirdgen.org.

 

Thanks, you guys. I will check these out!

 

turns out it was both the tach *and* the transmission! and the tranny guy also adjusted the TV valve, so that's fixed. thanks again.