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        General >> Problems >> overdrive 'thuds' in
        
(Message started by: the_machine on Sep 11^th, 2006, 11:20pm)

Title: overdrive 'thuds' in
Post by the_machine on Sep 11^th, 2006, 11:20pm

after getting my 24v back from the garage , they fixed the wishbones but now overdrive thuds in.

its not smooth anymore
it does not always do it though.

what have they done ???

if i drive with o/d off , theres no thud

Title: Re: overdrive 'thuds' in
Post by the_machine on Sep 12^th, 2006, 1:15am

its ok if you gradually accelerate, it only thuds if you have a bit of throttle on

Title: Re: overdrive 'thuds' in
Post by 97stateblue on Sep 12^th, 2006, 6:21am

I will be very interested to see if you get a solution to this one. My overdrive (fourth gear) has always come in with a thud, even on gentle acceleration. It seems (from an OBD trace) that the torque converter does not unlock between third gear locked and fourth gear locked states (unlike some other automatics I've checked). It does however unlock and relock if you ease up in fourth gear. Have you got access to OBD to see if yours is now the same. This problem was debated on the e-mail list some considerable time ago (this is my fifth year with the car, 24V Ultima 145000 miles)

Title: Re: overdrive 'thuds' in
Post by the_machine on Sep 12^th, 2006, 7:25pm

CURED CURED CURED CURED !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

OK heres what happened (and i dont know which thing cured it...but)

changed battery for bigger capacity (garage had fitted a small battery nickheads ! )

connected a OBD diagnostic tool and read some codes , THEN cleared the codes.
think the code read high voltage bank 2 code p161 i think (cant recall) , there was another code too, but i did not see it as i was not using the obd reader. anway, i did not have much hope, drove it home and its mint. smoothest gear changes i ever known.

i also messed with a plug under the car, the one that reads the crankcase revolutions, it was waterlogged but i dont think it was that. i was just checking the plugs on the engine loom, fiddling, but im sure it was the OBD code reset EVEN THOUGH IVE BEEN TOLD THAT DISCONNECTING BATTERY CLEARS CODES. IS THIS TRUE???

Title: Re: overdrive 'thuds' in
Post by 97stateblue on Sep 13^th, 2006, 4:37pm

Okay, pleased you're sorted, that's good news.
In terms of my version of the fault and how to cure it I can dispense with reading and clearing codes as I have done that many times.

Interestingly I went to FMD to buy the "correct" battery for the Scorpio (about three years ago) and later found they'd sold me one which was too small. An interesting coincidence that we both had too small a battery and both had the fault. I will certainly try to get a bigger one that next time it fails or possibly borrow one for diagnostic purposes.

Your final point about messing with the vehicle speed sensor (I assume that's what you mean) is also interesting. Although if it was faulty you expect the speedometer and other things to go wrong

Title: Re: overdrive 'thuds' in
Post by TiberiuS on Sep 13^th, 2006, 4:58pm

Well, hope you've really sorted it out, problems with my car have a nasty habbit of going away for a couple of weeks and then rearing their ugly heads again but good luck ;).

Regards, Bruce.