1990 Sonata transmission problem

[thorthor]

I am on vacation in Chile, and I have bought a 1990 Sonata with 1.8 engine and automatic transmission. The transmission shifts softly and at the right places when applying moderate power. The transmission fluid has a healthy, red color.

When applying more power in order to accelerate more rapidly, the transmission initiates a shift to a higher gear too early, and returns to the previos gear immediately. This will go on several times, resulting in a very uncomfortable ride and hardly any gain in speed.

I have never worked on automatic transmission, but I have the impression that the problem may be as simple as some valve malfunctioning, or a loose vacuum hose. It seems that the transmission is not "told" that the accelerator is depressed and tries to shift to a higher gear.

Any ideas?

[Rick.]

My dayghter had a 89 excel and experianced the same sort of thing. I took the car to 5 transmission shops and they all said it needed a new transmission. After a new transmission was installed the car performed the same. I took it to a sixth shop and the owner said before we do any transmission work we should have had the exhaust system checked for blockage. I did and they found the catylitic converter was plugged. The exhaust tech. smashed the guts out of the converter and bolted it back up. The car worked perfect and the transmission shop wouldn't give me a refund. I don't remember the detail but the transmission shifting on a Hyundia is very connected in some way to the passage of the exhaust gases as well as the RPM of the engine. Hope this helps. You may want to discuss this further with a Hyundia Tech. but my problem was never the transmission and yet 5 shops said to replace it. Rick.

[mazdatech]

the fluid is red you say well than its the wrong fluid if im not mistaken your trans takes spIII i'll bet you paid to have it "flushed" at a lube shop well you probaly flushed it down the toilet the only choice yuo have is to flush ut with the correct fluid and pray or replace the trans clean the trans cooler and use the correct fluid spIII turns brown once heated inside the trans this is normal