I have an 84 El Camino 305 3 speed automaticit runs great for 15 to 20 minutes after it is warmed up the transmission start shifting into high and a low speed of 25 to 30 it's driving me crazy can you
How is the transmission fluid level looking? You changed it lately? I HOPE it's not going south.
In the early emission years they had the transmissions set up to get into top gear as soon as possible after the system went into closed loop, the factory setting was final upshift at 30 mph light steady throttle. If your is shifting sooner than that then check the vacuum supply at the modulator valve on the tranny, it has to be manifold vacuum, if that checks good, then it could be the modulator valve itself, when they go bad it causes what they call stacked shifting. I've seen these put a transmission in high gear at 10mph, lugs the daylights out of an engine.
T.S. You da man! I didn't even remember that.
I have the transmission serviced and they checked everything so I don't know what the problem is I change the oil filter it only does that after the transmission is warmed up it starts shifting funny and engine misses constantly why what engine is cold shifts and runs good
That sounds like a vacuum leak, possibly an intake manifold gasket, that would explain the tranny shifting problem, You would n't notice it until it went into closed loop and the air fuel ratio leans out.
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