P38A slow to accelerate between 50 and 60 mph

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Baileyroverq

Baileyroverq

Active Member
Posts
167
Location
Woodley Berks
Hi can anybody point me in the right direction wifes 2.5 dse drives fine up until she hits 50mph then the car seems to have a dead spot it will accelerate but it crawls until it hits 60mph then it is fine again until she brakes below 50 and then it all starts over again could it be the turbo playing up ? as always any ideas greatly appreciated Thanks
 
Obvious starting point is a good service to make sure everything is as it should be.
Is it manual or auto?
If manual, try in different gears and see if it is road speed or rpm related.
 
If it's an auto at 50 MPH torque converter will be locked it will have to be kicked down to drop that out. Then it should accelerate.
 
Baileyroverq said:
ah what wammers says sounds about right but is there a way to fix that or should I just leave it well alone for now thanks for your answers
Click to expand...

No when torque converter is locked up, engine is directly coupled to gearbox, so there is no converter slip and engine will just be starting to get usable boost. As revs rise boost rises and gives more power, that is why at 60 MPH all is well. If you need to speed up quickly at 50 MPH in torque lock you will have to use kick down to get more revs more boost and more power.
 
Due to my petrol having an as yet undiagnosed flat spot, I nearly always drive in 3 until above 60mph.
 
wammers said:
Bet that does wonders for your fuel consumption. :D
Click to expand...
It actually, I think makes it better up to 40mph as it goes into 3rd gear lockup around 25mph if you're gentle with it.
If I'm doing 40mph+ for any more than a minute or so I drop it into D but when accelerating down the slip road I'll keep it in 3 until about 60mph then into D.
If I drive in D all the time, I get no lockup and down the sliproad, I have to kick down a gear to get over the flatspot so, yes, it might be slightly down on what it should be without the flatspot but in its current condition I think it's probably slightly more economical.
That said, if I was so worried about economy I'd have bought something else!
 
I put foot down a bit (around 3000rpm) at 40-45mph stopping torque converter locking up and let off when it hits 60mph and let it lock in. I usually cruise around 60. I in no hurry
 
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