AndyGBH
Member Since: 09 Dec 2012
Location: Bristol
Posts: 11
  
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| Strange Oscillation of the Revs ! SOLVED ! |
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My Discovery 3 diesel 2005 automatic - only had it a couple of weeks and getting through the gremlins one by one.
A new one on me is that the engine revs oscillate - particularly bad at 1500rpm to 2000rpm. The 'dip' in revs of about 200 is accompanied by a noise - almost as if a compressor is going off. This cycle repeats every second or so but disappears at higher revs, though the loud noise doesn't necessarily.
It is the same sensation as blipping the throttle - revs change, car starts to decelerate, revs go up, car accelerates, although he actual acceleration/deceleration is smoothed out by the gearbox.
I have no issues from the gearbox - it engages and changes without any problems - very smooth.
The engine revs don't oscillate when in neutral - even at higher revs - only under load (whether accelerating, cruising of on the over-run).
Any ides?
NOW SOLVED
Got a new torque convertor fitted by those very nice people at Bristol Transmissions.
This was about £1000k + vat and included new gearbox oil and filter, switch as well as the coupling and all labour. Given that this price fitted is about the same price as a dealee TC only, I'm pretty happy and their customer service is good to.
I thought about just a gearbox flush but agreed that this is more likely a temporary fix, which is fine if you don't intend to hold on to the car, but not so fine if you do. It's probably less fine if you put the car under a lot of load too. Also the flush is usually about £250, which is pretty much included in this cost anyhow and so the difference isn't quite so bad.
So in summary, rule out everything else like I did (check MAF, MAP, injectors (does it run rough) but for sure, if you get oscillation on over-run as well as under load and you get juddering order high load, suspect the TC. Thereafter it is up to you, flush or change, depending in your plans for the car.
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 10th Dec 2012 7:36 pm |
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