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Author Topic: Questions about semi-auto driving technique and MPG  (Read 6973 times)

sirgoldi

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Questions about semi-auto driving technique and MPG
« on: October 29, 2020, 03:35:02 AM »

Hi! I don't actually have ForFour but Mitsubishi Colt with 1.5 95 BHP diesel engine which makes it very similar car to ForFour so I think you might be able to help me!

1. What MPG should I reach with this car? I was getting 45 MPG with broken thermostat (65 C) and after fixing this issue (now is 86 C) MPG hasn't changed at all. I still reach around 45 MPG in same driving conditions (city and ring road driving but for hours at work so engine is 90% warm). I believe thermostat change should help?! My previous car (Citroen C4 1.6 HDI 90) was achieving 55 MPG at this time of the year so I was expecting something around this number considering Colt is lighter but also has 5 BHP more... But I don't know if I should believe cars computers...

2. What is the best way to drive this semi-auto gearbox? I was going through many threads on this forum and I can't find definitive answer. What I do is driving like 50:50 in auto and manual mode. Generally speaking I don't like engine braking so use manual mode when light ahead of me change to red. However, when I stop on lights for like 45 seconds - 1 minute should I disengage to Neutral from A/1? This is what mechanic told me - keeping it on A is like keeping clutch all the time pressed in normal manual gearbox. Made sense to me so now for longer stops I just engage N. Should I?

3. Why "creeping" sometimes works and sometimes not? Literally. When I leave car on A/1 it sometimes doesn't move, sometimes moves for a while after sometimes after a while it just starts to drive slowly.

4. I read a bit about adjusting clutch/actuator. I bought this car used of course so I have no idea if it's even been done but generally gearbox works totally fine, clutch not slipping at all so I think I will leave it be. Or I should go to Mitsubishi for adjustment? The only problem is that when it's raining heavily gearbox likes to show "0" but I read it's basically everybody problem and going quick from A to R/applying brake hard helps to I can live with that.

Thank you. :-)
« Last Edit: October 29, 2020, 05:06:37 AM by sirgoldi »
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CrazyG

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Re: Questions about semi-auto driving technique and MPG
« Reply #1 on: October 29, 2020, 02:54:43 PM »

I have a 1.5 CDi AMT...and both my daughter and ex wife have 1.3 AMT's.

We have all found that around town is best to use it as a manual as
the AMT electronics tend to hold on to each gear too long...though
we all agree that sometimes if in stop start traffic is best to go the A.
On motorways...we all stick it in A.

If you have fitted or had fitted the correct thermostat because it
appeared old one was not working, then mpg should be better
than when you had broken thermostat. See if it improves if you
use manual around town and most journeys.

There seems to be more problems with the AMT's if you take them
out of 'drive' (either A or manual) when stuck at standstill for long
periods. I wud suggest turn engine off as the actuator will then be
'released' rather than permanently under load for long periods.
Reason l say that is that the electronics of the AMT are 'adaptive',
so if you keep putting it in N with engine running then more often
than not it won't give you 'creep' as it has 'learnt' that you often
select N with engine running and car not moving..so that becomes
the memorised setting. (Hope you understand that part)
Clutch adjust should be undertaken once a year at the annual service
and if you are lucky a Mitsi garage won't charge extra for that for
you Colt. (If you had a Smart and used MB, they charge !)

Re the 'O' that sometimes comes up....yes it is problematic...
My daughters 1.3 AMT does that every so often goinf from A
(or manual) and into R....even after we changed the actuator
for a brand new one thinking it would cure that problem !
But as you say...one can live with that even if it is a bit of
a pain sometimes.
« Last Edit: October 29, 2020, 02:56:08 PM by CrazyG »
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454 - Brabus (mapped, Willwood brakes, coilovers etc etc)
454 - Passion CDi 95hp (manual, full Brab body kit, coilovers etc)
454 - Passion 1.3 (manual, Brab body kit, lowered etc) [SORN'd]
451 - Pulse Turbo [my daily drive] (mapped, coilovers etc)
450 - 'Widestar' Passion 700cc [SORN'd]

sirgoldi

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Re: Questions about semi-auto driving technique and MPG
« Reply #2 on: October 29, 2020, 10:44:10 PM »

Thanks a lot for complex answer.

You have Smart, yes? May I ask what MPG you get with your 1.5 CDi? In city, mixed, motorways? 6 litres/100 km (it's like 45-46 MPG) is all I can get with my Colt in the city. This is not bad but why heavier Citroen C4 1.6 HDI was doing 0.7 l better is beyond me! But maybe it is just bullsh*t from computer which I shouldn't trust. :-)

Have you already changed clutch? Is so, at what mileage? How about dual-mass flywheel?
« Last Edit: October 30, 2020, 11:03:35 AM by CrazyG »
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CrazyG

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Re: Questions about semi-auto driving technique and MPG
« Reply #3 on: October 30, 2020, 11:16:01 AM »

I never believe any 'onboard' computer. I note fuel I put
in and mileage covered and work it out.
My CDI is remapped...and I used to get well over 60+mpg
on motorway driving at high speed....and around town it
was about 45+mpg, but...I never drove it slowly. If I had
then I am positive that I would have managed 50+mpg
even on 205x40 profile tyres that have more 'drag'/friction.

Clutch was replaced twice as the little actuator would not
release the pressure plate to bite on the driven plate fast
enough to transfer the extra power I had available.
(125bhp + 248ft.lb of torque !).  The dual-mass flywheel
had to be replaced once due to accelerated wear because
of the remap....till I changed my driving style and backed
off the throttle between gear changes (in manual mode).
« Last Edit: October 30, 2020, 11:18:07 AM by CrazyG »
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454 - Brabus (mapped, Willwood brakes, coilovers etc etc)
454 - Passion CDi 95hp (manual, full Brab body kit, coilovers etc)
454 - Passion 1.3 (manual, Brab body kit, lowered etc) [SORN'd]
451 - Pulse Turbo [my daily drive] (mapped, coilovers etc)
450 - 'Widestar' Passion 700cc [SORN'd]

Ocracoke

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Re: Questions about semi-auto driving technique and MPG
« Reply #4 on: October 30, 2020, 11:51:31 AM »

Quote
What is the best way to drive this semi-auto gearbox? I was going through many threads on this forum and I can't find definitive answer. What I do is driving like 50:50 in auto and manual mode. Generally speaking I don't like engine braking so use manual mode when light ahead of me change to red. However, when I stop on lights for like 45 seconds - 1 minute should I disengage to Neutral from A/1? This is what mechanic told me - keeping it on A is like keeping clutch all the time pressed in normal manual gearbox. Made sense to me so now for longer stops I just engage N. Should I?

Generally speaking, around town it is manual and on the motorway, it is either/or for me. I've tried driving around town in Automatic and it's... OK, it being the best descriptor I have for that but I know I can do better in Manual. Plus, mine has paddle shifters, be a shame not to use them. :P

The engine braking in my car is fairly minimal compared to my 450's (the 1998-2007 city-coupe/fortwo). I suspect this is because of the narrower ratios between each gear, especially between 5th and 6th so I do find myself changing down twice when needing to slow down with some rapidity.

As G implies, it can be more fincikity to put the car into N and then back into 1/A when starting and stopping. I used to think the same as you in that it'd keep the clutch released as you held your foot on the brake or on the handbrake but I don't think that is the case. If that was true, I'd imagine the clutch would have burnt out in mine long ago and you would feel the car wanting to move forwards at stationary (much like as you might feel if a manual car had its brake applied on and the clutch pedal released slowly to the biting point). In my experience anyway, it just sits there until I let go of the brake and then I can feel the power slowly being applied, as if the actuator is slowly releasing the clutch to bite.

The onboard computer is a nice indicator, yes but it isn't that accurate in my experience.

Quote
Why "creeping" sometimes works and sometimes not? Literally. When I leave car on A/1 it sometimes doesn't move, sometimes moves for a while after sometimes after a while it just starts to drive slowly.

I can't say I've ever experienced the car not move in 1/A under its own steam where everything was working. That being said, it is fairly sensitive to the gradient and the only time I've ever experienced the car not move under its own steam was when the ABS/ESP was disabled.

Quote
I read a bit about adjusting clutch/actuator. I bought this car used of course so I have no idea if it's even been done but generally gearbox works totally fine, clutch not slipping at all so I think I will leave it be. Or I should go to Mitsubishi for adjustment? The only problem is that when it's raining heavily gearbox likes to show "0" but I read it's basically everybody problem and going quick from A to R/applying brake hard helps to I can live with that.

The "0" problem is, I think, a situation where the car expects something to have been done within a certain time frame and then that doesn't happen. This is a fairly common occurrence and save for any disaster with the clutch actuator, is usually remedied by a swift movement back to 1/A and then back again. I would typically recommend a indie for clutch actuator adjustment but it depends on wherever they have the right equipment or not (in the Smart world, that is the Mercedes STAR system). I think I've heard tale of Snap-Ons being able to do it these days but I can't confirm that and I wouldn't know what Mitsubishi use for their diagnosis system either.
« Last Edit: October 30, 2020, 11:52:20 AM by Ocracoke »
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2004 ForFour 1.3 AMT - The yellow 454!

http://www.forfour.co.uk/forum/index.php?topic=5224.0 - The WirralSmarts mod/upgrade thread

1x 454 1.3 S-A, 1x 450 RHD mk5, 1x 450 mk5 CDI

mr singh

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Re: Questions about semi-auto driving technique and MPG
« Reply #5 on: October 30, 2020, 03:56:32 PM »

I think I've heard tale of Snap-Ons being able to do it these days but I can't confirm that and I wouldn't know what Mitsubishi use for their diagnosis system either.

mitsubishi should be able to adjust the clutch with there diagnostic kit, as for the Snap on machines, i know that it will do it on the forfour as i have a Snap On Solus (which is only good for cars up to 2012 as i refuse to pay ££££ for every update from 2012 to now) so i can only assume it would be the same with the Colt, although i can not confirm as iv not had the honour of plugging it into an AMT Colt.

as for the average MPG reading, ill throw my 2 pence in to this. although i dont have a diesel i do have the multifunction display in my forfour and it most certainly over reads. iv had an average of over 40 MPG on a tank but when i calculated it on my MPG app it came out with high 30's
« Last Edit: October 31, 2020, 11:20:48 AM by CrazyG »
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Fortwo MK3 (2007-2010) Top speed 85 MPH. maxed* 98 MPH
Forfour 1.1 (2010-2015) Top speed 103 MPH. maxed* 110 MPH
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