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        General >> Problems >> Autobox change-up speed
        
(Message started by: Neil W on Apr 17^th, 2005, 1:53pm)

Title: Autobox change-up speed
Post by Neil W on Apr 17^th, 2005, 1:53pm

The other day I used kickdown whilst in economy mode to overtake some slow(ish) cars and noticed that it didn't change up a gear until about 6,000rpm (at erm 95mph ;D). In the past this has only happened in sport mode, and in economy it used to change up at much lower revs.

Do I have a problem, and if so how do I fix it?

Autobox is a Ford fitted recon with about 42,000 miles use. Changes very smoothly up or down, but when stationary there is a slight pause and jerk on engaging drive or reverse. Car has 92,000 on the clock. Owned the car from new.

Neil W.

Title: Re: Autobox change-up speed
Post by scorpio_man on Apr 17^th, 2005, 2:06pm

hi there

kick down is controlled by the ecu from various sensors. do you have an obd-2 lead or multi-meter? check the throttle postion sensor for a 'nice flow'. on obd-2 it starts at about 16% up to 80%+. fully open (kick down) is at about 93%.

the car's properly just got a bit confused, and held the gear at bit longer than usual because your foot didn't lift off a bit.

Title: Re: Autobox change-up speed
Post by mr._floppy on Apr 17^th, 2005, 2:08pm

WOW! 6000 rpm, I don't think mine would get to that speed.

If you ease off on the pedal it should pop itself into overdrive eventually , but if you've got it to the floor, you,re asking the engine to give its maximum power , and that's what it's doing.

Title: Re: Autobox change-up speed
Post by Neil W on Apr 19^th, 2005, 11:34am

Thanks for the comments, guys. Yep, the 24v will reach 6000 revs all too easily ;D but even in second gear that is about 95mph.

I understand that easing off the accelerator will induce an upward gear change, but my point was that the speed at which change up occurs in economy kickdown mode has altered. I therefore wondered if this was telling me something. Unfortunately I don't have an OBD lead, and woudn't know how to use it if I had it :P!

As far as I know the MAF has never been cleaned, not even by the FMD during services (at least it is not mentioned on work sheets), so would that be a possible cause of the problem? Cleaning MAF's seems to have become "the thing to do" on this site, and the apparent solution to many problems, but I prefer to leave well alone unless it is absolutely the right thing to do.

Regards,

Neil W.

Title: Re: Autobox change-up speed
Post by scorpio_man on Apr 19^th, 2005, 9:54pm

hi there

cleaning the MAF won't do any harm. have a read of http://www.fordscorpio.co.uk/cleanmaf.htm http://www.fordscorpio.co.uk/obd2scan5.htm

Title: Re: Autobox change-up speed
Post by Thunderchild on Apr 20^th, 2005, 12:37pm

Hi there,

Got to say that my 24v does exactly the same thing and always has. The point is that whether you are in sports or economy mode makes no difference when your foot is flat on the floor... the car is going to accelerate as hard as it can all the way up through the rev range.

When you have the joy of acceleration like that, does it really matter if it holds the gear a bit longer????

HTH

Thunderchild

Title: Re: Autobox change-up speed
Post by Neil W on Apr 22^nd, 2005, 1:12pm

Thanks again, guys.
Comment about flooring the gas pedal telling the engine to go to max revs before changeup irrespective of mode had't occurred to me before :-/.
And I guess I'll have to clean the MAF afterall ;D, as one way or another it should either solve the problem or eliminate the MAF itself as a contributor to the problem.

Regards,

Neil W.

Title: Re: Autobox change-up speed
Post by mr._floppy on Apr 22^nd, 2005, 11:39pm

Actually, I find the kickdown facility rather annoying at times, when you are tootling along at 65 on the motorway and need just a tad more revs to leisurely overtake a lorry , the merest touch on the accelerator causes the gear box to drop a cog . Completely unecessary ( or maybe the kickdown needs adjustment ).

Title: Re: Autobox change-up speed
Post by scorpio_man on Apr 23^rd, 2005, 7:30am

hi there

in that situation, it's better to switch o/d off. the revs will rise about 500 rpm, make a perfect over taking manoeuvre.

hth