SC88Pathy Posted November 23, 2005 Share Posted November 23, 2005 I'v tried searching but can't find anything on this. My engine fluctuates between 2000 and 1750 and 1500 (does that make sense?) RPM when I let it coast at between about 52 and 48 MPH. When I get above or below those speeds it goes away. When I'm accelerating or coasting downhill it doesn't happen. It's not just the tach either I can definatly feel the engine doing something. I think it might be the tranny trying to pick between 4th and overdrive, but it doesn't quite feel like the tranny is shifting... Any ideas? :help: Link to comment Share on other sites More sharing options...
Precise1 Posted November 23, 2005 Share Posted November 23, 2005 I'd think you could feel it if the tranny was trying to shift, but then 500 rpm is too big of a change not to significantly increase/decrease speed if it wasn't shifting... Do you have an aftermarket tranny cooler ? Is the tranny fluid level correct ? How old/what condition is it in ? Have you checked to see how hot the tranny cooler return line is ? The only other thing I could even guess at is the throttle position sensor, but I'd check all the other stuff first... GL ! B Link to comment Share on other sites More sharing options...
SC88Pathy Posted November 23, 2005 Author Share Posted November 23, 2005 I'v been meaning to get the AT fluid flushed and changed for a while now since it's more pinkish than reddish. I'v also been meaning to install or get a tranny cooler installed. Guess it's time to get that done! It doesn't fluctuate 500 RPM at a time, more like 250 -100 RPM at a time. Link to comment Share on other sites More sharing options...
Precise1 Posted November 24, 2005 Share Posted November 24, 2005 Flush the tranny and put in a different cooler. Just call it maintenence and go from there... B Link to comment Share on other sites More sharing options...
Simon Posted November 24, 2005 Share Posted November 24, 2005 ^^^ What he said!!! If you're running an 88, and you've still got the stock cooler, consider yourself lucky you haven't had a catastrophic failure of the AT yet, as many, much younger, Pathy's have. Get that cooler changed out pronto....and remember to COMPLETELY BYPASS the stock cooler when you install the new one. Good luck. Link to comment Share on other sites More sharing options...
revgolem Posted November 25, 2005 Share Posted November 25, 2005 Might also want ot look at the throttle Position Sensor. sometimes they can develope dead spots and give false readings, causing more or less fuel than needed to be dumped in. Can cause the types of problems you are describing. Link to comment Share on other sites More sharing options...
SC88Pathy Posted December 8, 2005 Author Share Posted December 8, 2005 OK stupid question time: If I install a tranny cooler am I going to have to drain the AT fluid? If so where is the drainplug for the AT fluid? Link to comment Share on other sites More sharing options...
Precise1 Posted December 8, 2005 Share Posted December 8, 2005 No, you shouldn't have to drain any, but you will spill some, so be prepared. I don't believe there is a drain plug, I think you have to pull the pan, which doesn't want to come all the way off due to clearance issues. This is just what I remember reading. Depending on how old the tranny fluid is, you may just want to do yourself a favor and replace it. Does anyone know if it is ok to disconnect a cooler line and fire up the truck to pump the fluid out ? Will it get most of it out ? Will it hurt anything to do this for a minute or two ? Automagic ignorant here... B Link to comment Share on other sites More sharing options...
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