2000 Crown Vic - Transmission Slipping

I have a 2000 Crown Vic (Police Interceptor) and the tranny slips. Sometimes it will not shift into OD when i know it should, and then finally it will, not redlining before it does, but you can just tell
when it should should, and its going beyond that. Also under full throttle, it will stay in gear and not shift up sometimes, then when it shifts into gear (99% smooth, 1% of the time it shifts really hard). My friend has a 96' ford ranger and is having similar problems. I have read on a few forums that a tune-up would help. Does anybody have any troubleshooting tips or things i can try?
Thanks!
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wrote:

It does not sound like you are describing a "slipping" transmission. Rather, it sounds like you may have an erratic shifting transmission. Your transmission is electronically controlled and may store fault codes to aid in diagnosis. You may have a very simple problem like a bad MLPS sensor (nuetral switch) or just a loose connection. Youyr car has what is called OBD2 emissions control system. It can store quite a bit of info on the engine, transmission and emissions system including fault codes. If you have something like an Autozone in your are, they may read any codes for you free of charge in hopes you will buy the repair parts. A dealer can certainly do this for you to a much greater depth and degree of completeness as well as many well equipped independant shops. If you want to try one of the freebie services, make sure you write down the exact code and fault description given and post them back here. There are a couple of very good and helpful people here to help you figure out how to correct the problem. Rest assured that this problem will get worse and may result in extended collateral damage to a now easily repaired transmission if you continue to drive it this way.
Good luck Lugnut
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thanks man, i replaced all the spark plugs due to a recommendation from a person on http://www.crownvic.net and it sure seems to have fixed it, a few of the spark plugs looked pretty bad physicalled, allot of black, 2 plugs had very shallow gaps, much tighter than the . 054 that autozone told me it should be. I couldn't tell that it was running rough, but it feels completely different now. you can hear all the engine sounds on my 89' VW Golf, heck you don't even need a tach, it has no noise damping material at all, the Vic, you can barely hear it running with the windows up! I'm gonna have a shop do the tranny fluid flush, just for best results.. thanks for your reply!!!
-Rpm-
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wrote:

Thanks for the feedback. One of the basic rules of transmission diagnosis is to be sure the engine is properly tuned. Just how thw hell could the plug gaps close if they were set correctly when installed? Or, were they fouled that bad. The 4.6L V8 usually runs a lot cleaner than that. If they were fouled that bad, you may want to keep an eye on oil and fuel consumption for other problems
Lugnut
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6000rpm wrote:

The first thing you should try, is a transmission fluid change... pretty easy on these cars, drain the torque converter while you're at it, and throw in a liter of transmission slip fix (lucas).
i bet that will solve it...
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