Thread: Torque Converter problem?

Originally Posted by grendawkin

When I accelerate my 2003 Disco2 TD5 automatic, the revs rise at once but the Car only speeds up slowly, sometimes not at all if the road is at an incline, Better on the flat, but the revs always rise & the car is slow to pick up.
Is this normal for the Car or is it a potential Torque Converter problem?
Appreciate any advice, thanks

Would say that your sprags or converter is on the way out. Overhaul required.

Tony

how about we check the oil level and condition first...

BEFORE doing anything to the auto, borrow a new/known air flow meter and swap it over. I had a similar issue where mine was free revving, wouldn't drop ointo 4th. Just revved and basically stopped and went back to first and limped up hills then when flattened out came good. Does yours surge as well? What happens is the meter stops detecting air so cuts fuel but O2 sensors are detecting oxygen, lots so it adds fuel and plays with timing etc and swaps from open to closed loop modes and tries to work itself out all the while the gearbox is in some kind of limp mode where 4th cannot be engaged and converter doesn't lock up. Then the ECU gets a signal from the meter showing flow and so goes "oh no, more air add fuel", this fuel/no fuel causes the surging.

Not saying this is it but I'm down $3k for a rebuild I didn't need (although it's nice to have had it rebuilt just after swapping to a 4.6 as well). Just that it a lot cheaper to buy a new meter.

How high do the revs rise before it picks up ? Mine (TD5) was progressively getting worse but didn't always "slip" and eventually was occasionally peaking out at up to 3000RPM before it engaged - diagnosis worn out transmission - result I have just had an OEM rebuilt transmission (complete with torque convertor and new XYZ switch) fitted $$$$s. Now it drives as it should in first and reverse BUT IT WON'T SHIFT OUT OF FIRST unless you really push it hard then it sometimes goes to second then to limp mode with flashing M&S and a fault code (Fault 22 Stall speed Monitoring ) - experienced L/R mechanic is still trying to sort that one out. All the wiring connections have been checked and the correct indications (P, N, D etc) show on the instrument panel.
The OEM claims the transmission has tested OK and the problem is with the car side! I suspect that there is a problem with this transmission that the OEM's test box cannot see or replicate.
After reading up on this fault and running through the fault tree I am starting to suspect a faulty Output Speed Sensor and/or damage to the wiring or its screen inside the transmission. (The OEM has already swapped out this sensor and the valve block which didn't fix the problem.)

We are about to try a replacement ECU as well as another gearbox harness although nothing has been changed there.

Any clues out there ?

Might be ringing NSW Fair Trading soon.

There's something about resetting the adaptable values of the trans ecu to remove previous learned behavior.

I am not really able to check the gearbox fluid which was renewed about a month ago by the dealer, as was the XYZ switch.
It is just that when I accelerate in any gear, the revs immediately shoot up to 2500 - 3000 rpm but the car does not go any faster, only gradually the speed builds up then the revs settle back to about 2000rpm.
I have had this car, which has only done 55k miles, for 3 months & it has been this way from the start, not getting any worse.
My problem is, is this normal or is there a fault?

Grendawkin, take Blknights advice, what ever the cause the trans is slipping meaning fluid and things are getting hot. You are going to have to get the box hooked up and diagnosed by people that know how d2 autos run.
Hope it works out well

I have now carried out the Torque Converter test as outlined in the Disco2 Workshop Manual (see below)
The result was the revs settled to about 2700rpm, so it looks as if my fears of a faulty Torque Converter were unfounded.
What a relief!!!

Stall Test
Testing
1. Chock the wheels and fully apply the
handbrake.
2. Start the engine and run it until it reaches
normal operating temperature.
3. Apply the footbrake and select 'D'.
4. Fully depress the accelerator pedal and note
the tachometer reading. The figures should be
as given below. Do not carry out stall test for
longer than 10 seconds, and DO NOT repeat
until 30 minutes have elapsed.
l V8: 2200 to 2400 rev/min
l Diesel: 2600 to 2800 rev/min
5. A reading below 1300 rev/min indicates a
torque converter fault, ie stator free-wheel.
6. A reading between 1300 and 2200 rev/min (V8)
or between 1300 and 2600 rev/min (Diesel)
indicates reduced engine power.
7. A reading above 2400 rev/min (V8) or above
2800 rev/min (Diesel) indicates clutch slip.
NOTE: The figures quoted above were
measured at sea level with an ambient
temperature of 20°C (68°F). At higher altitudes
or higher ambient temperatures, these figures
will be reduced.