Torque converter slip in auto

Torque converter slip in auto

Postby Saliya on Sat Jun 03, 2017 6:52 am

Hi all,
I've noticed that the auto trans. in my MQ GLS slips excessively between the higher gears (4-5th) and is hesitant to lockup around 80km/h. But around 90-95km/h locks up solid. This is a bit of an issue because of the road speed limits around my area. Still slips even if I change gears manually.

Does anyone else notice this? I think it's affecting fuel economy badly at highway speed. On a flat highway stretch the best I would ever get is 8.8l/100km. Stealer says it's "normal" and refuses to even road test it.
Saliya
 
Posts: 14
Joined: Tue May 30, 2017 6:42 am


 

Re: Torque converter slip in auto

Postby WUNSIE on Sat Jun 03, 2017 5:29 pm

When you say slip I take it you mean the converter is open.
You will find it will be in 4th, then the converter locks up around 65kph, then under ideal conditions,
light throttle it will change up to 5th O/D and the converter will lock up @ 90kph at least that's what mine does
User avatar
WUNSIE
 
Posts: 405
Joined: Sat May 28, 2016 5:40 pm
Location: NSW Hunter Valley

Re: Torque converter slip in auto

Postby Saliya on Sun Jun 04, 2017 4:40 pm

Thanks for your response Wunsie. I experience the same shift points that you've mentioned. I'll be towing with this ute in a few years time so was worried about how much the torque converter stays open as it can overheat the transmission.
Saliya
 
Posts: 14
Joined: Tue May 30, 2017 6:42 am

Re: Torque converter slip in auto

Postby Saliya on Sun Jun 04, 2017 4:41 pm

May have to invest in a lock up kit when I eventually get a camper
Saliya
 
Posts: 14
Joined: Tue May 30, 2017 6:42 am

Re: Torque converter slip in auto

Postby WUNSIE on Sun Jun 04, 2017 5:13 pm

Depending on the weight you will be hauling, you might find it will handle the load, after all the transmissions have seen years of service in the Pajero,s and look at some of the bloody big full size vans you often see hanging off the back of them, also when the converter unlocks in OD 5th, it puts the engine more or less straight back into its Torque curve.
Saliya might be a good Idea to have a read thru a Pajero related forum and see if anyone has done what you want to do, if you do find something, let us know as I wouldn't mind having a read myself,
Cheers
User avatar
WUNSIE
 
Posts: 405
Joined: Sat May 28, 2016 5:40 pm
Location: NSW Hunter Valley

Re: Torque converter slip in auto

Postby JohanB on Sun Apr 15, 2018 6:27 pm

Yes I experiance the same problem.
I find the converter lockup speed is excessively to high. It locks @95 and opens @90Kph on 5th gear @around 2000revs. Quite high for a diesel!
When you drive, light loaded, on a 90Kph limited highway, the lockup goes in and out all the time and accordingly the revs goes up and down by 2-300revs. Very disturbing! Feels like the drive shaft is made of rubber band!
This also hurts the already really bad fuel economy. Difficult w/light load to get under 9l/100km on mixed highway/suburban driving.

I also own a Isuzu D-Max -2008 5-speed manual and when I drive it the same style it only uses only around 6,5l/100km

So what I like to ask the community here, is if there is a way or an easy software update to lower the lockup speed to a more normal 65-70kph @5th gear?
I know about the aftermarket ”lockup kits” but hope there is an easier way.

JohanB, L200 (Triton) 2,4 Aut-16, Sweden
JohanB
 
Posts: 2
Joined: Sun Apr 15, 2018 5:37 pm

Re: Torque converter slip in auto

Postby JohanB on Sun Apr 15, 2018 7:28 pm

WUNSIE wrote:When you say slip I take it you mean the converter is open.
You will find it will be in 4th, then the converter locks up around 65kph, then under ideal conditions,
light throttle it will change up to 5th O/D and the converter will lock up @ 90kph at least that's what mine does


The converter don’t lock up @65Kph in 4th gear. It is more @75-80Kph it locks up.
Then as you wrote (under light load), the 5th gear goes in and the converter opens again and finally locks up @95Kph. Not a very nice gear change scheme.

If the converter instead locks @55Kph in 4th gear, it will (under light load) change to 5th without opening the converter again in between gears.
A much more drivable and correct gear change sequence.

L200 (Triton) -16, Sweden
JohanB
 
Posts: 2
Joined: Sun Apr 15, 2018 5:37 pm

Re: Torque converter slip in auto

Postby Saliya on Sun Sep 16, 2018 10:40 am

After 38,500 kms on the clock there's no difference in fuel economy or shift pattern. Should also add that the auto transmission doesn't drop gears when descending over a long distance with brakes applied, so requires manual shifting. It's quite hard on the brakes as the car coasts rather than applying engine braking. The same roads driven in a similar 5 speed automatic,Hyundai Imax (2.5 litre) and with similar load worked a treat, with the transmission downshifting on application of brakes in a short time on long descents. What was remarkable was the fuel economy, with the Imax returning 7.7 L/100km vs the Triton 9.4 L/100km, with the converter locking up early in the Imax (75km/h in 5th gear).

Note: the Triton does not have any modifications to increase drag, has 38psi road tyre pressures on factory HT tyres.

If other owners could comment on whether or not the auto transmission downshifts on descents with brakes applied, it would really help to pinpoint whether there is a programming issue with the auto trans as mentioned by JohanB, or that it's normal and just have to live with it. If the former is true then it will warrant a trip to the Mitsi service department.
Saliya
 
Posts: 14
Joined: Tue May 30, 2017 6:42 am

Re: Torque converter slip in auto

Postby Saliya on Sun Sep 16, 2018 10:44 am

WUNSIE wrote:Depending on the weight you will be hauling, you might find it will handle the load, after all the transmissions have seen years of service in the Pajero,s and look at some of the bloody big full size vans you often see hanging off the back of them, also when the converter unlocks in OD 5th, it puts the engine more or less straight back into its Torque curve.
Saliya might be a good Idea to have a read thru a Pajero related forum and see if anyone has done what you want to do, if you do find something, let us know as I wouldn't mind having a read myself,
Cheers


Will do Wunsie. I've noticed before that you report very good fuel economy from your rig. I'm wondering whether this may be due to your auto trans behaving better than mine. Just curious!
Saliya
 
Posts: 14
Joined: Tue May 30, 2017 6:42 am

Re: Torque converter slip in auto

Postby xmanstauncher on Tue Sep 18, 2018 11:00 am

Hey mate, I have an auto MQ and I can say mine doesn't downshift on descent with brakes applied, have to manually do it. I think it downshifts with cruise control on though. I also find it annoying that the torque converter will go between being locked and open in 5th gear when doing around 80kph
xmanstauncher
 
Posts: 5
Joined: Tue May 03, 2016 10:42 am

Re: Torque converter slip in auto

Postby WUNSIE on Tue Sep 18, 2018 5:20 pm

Had a Toyota Hilux 4.0 V6 , purchased new,and apparently had the same auto in it as my MQ, and in regards to the Hill Descent controlled braking, all I can say is I with the feature was active on the Triton, fantastic when travelling down an incline, tap the brake pedal, and it would drop back a cog, the engine braking maintaining the speed, get to the bottom, apply slight throttle and it would change back up, or continue to apply engine braking until stopped, cant fault it when towing
User avatar
WUNSIE
 
Posts: 405
Joined: Sat May 28, 2016 5:40 pm
Location: NSW Hunter Valley

Re: Torque converter slip in auto

Postby Saliya on Fri Sep 21, 2018 6:53 am

So it seems there are vehicle to vehicle differences with regards to auto transmission behaviour. What you describe is what some other owners here and I expected Wunsie, but certainly not the case. Will bring this up at the next service but I’m not holding my breathe.
Saliya
 
Posts: 14
Joined: Tue May 30, 2017 6:42 am


Return to Drive Train Components

Who is online

Users browsing this forum: No registered users and 3 guests