Ford Mondeo - Takes about 1 second to accelerate from the lights

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Wed 24 Nov 2010 07:43
Ford Mondeo - Takes about 1 second to accelerate from the lights - andymcgill

I have a Mondeo 2010 turbo diesel. It has an intermittent problem where if you stop at the lights and accelerate, it may take a second before it accelerates. This is not turbo lag. It happens more at heavy throttle than light.

It has also happened at cruise speed and attempting to accelerate results in no change to the tacho and no increase in speed.

Another problem which may or not be related is that in D (Drive) position, sometimes it goes to rev limit and won't change up gears.

Reply | Report as offensive | Link
Wed 24 Nov 2010 09:01
Ford Mondeo - Takes about 1 second to accelerate from the lights - madf

Why ask us when it's under warranty - and brand new.

Dealer job.

Reply | Report as offensive | Link
Thu 25 Nov 2010 05:31
Ford Mondeo - Takes about 1 second to accelerate from the lights - andymcgill

I have taken it back to the dealer twice and they can't fault it.

Reply | Report as offensive | Link
Wed 24 Nov 2010 10:25
Ford Mondeo - Takes about 1 second to accelerate from the lights - craig-pd130

Sounds like a glitch in the autobox brain, or a sensor fault.

Take it back to the supplying dealer, tell them the lack of drive away from traffic lights / junctions is potentally lethal, and ask if the gearbox control unit can be interrogated for faults, and if there is a software upgrade available.

Reply | Report as offensive | Link
Wed 24 Nov 2010 14:26
Ford Mondeo - Takes about 1 second to accelerate from the lights - jc2

Both of these could be caused by fault in "fly-by -wire" throttle.

Reply | Report as offensive | Link
Wed 24 Nov 2010 16:28
Ford Mondeo - Takes about 1 second to accelerate from the lights - injection doc
do you stop at the lights and hold the car with your left foot ? you will find if you do when you hit the gas and release the brake the throttle lags something chronic.
The brake must be released before you touch the throttle, although you may think you release the brake first the PCm will know and hold the car back, it will make it feel like the fuels gone!
Reply | Report as offensive | Link
Thu 25 Nov 2010 05:37
Ford Mondeo - Takes about 1 second to accelerate from the lights - andymcgill

This one sounds quite logical. I will monitor my driving. Thanks.

Andy

Reply | Report as offensive | Link
Thu 25 Nov 2010 06:00
Ford Mondeo - Takes about 1 second to accelerate from the lights - andymcgill

Sorry. I missed the point with the left foot. I only use the left on manual clutches. Unfortunately, this is not my problem with autos.

Reply | Report as offensive | Link
Thu 25 Nov 2010 05:34
Ford Mondeo - Takes about 1 second to accelerate from the lights - andymcgill

This was my initial thought. I am assuming that the throttle is linked to a variable resistor.

Andy

Reply | Report as offensive | Link
Thu 25 Nov 2010 09:55
Ford Mondeo - Takes about 1 second to accelerate from the lights - injection doc

OK Andy , worth checking then that the brake lights go off the second you release the pedal ! a sticking switch could give you the same symptons, and it only has to be a fraction of a second delay. This fault would not flag up iether.

You could try and produce the hick up by just touching the brake pedal , enough for the lights to be on and hit the accelerator, if it gives you the same symptons you know it may be brake light related. Suggest you try some where quiet.

The throttle is whats called fly by wire and is delayed if the brakes are applied, the signal comes from the brake light switch, often 2 curcuits or even 2 switches and then the signal goes to the PCM

Reply | Report as offensive | Link
Thu 25 Nov 2010 11:01
Ford Mondeo - Takes about 1 second to accelerate from the lights - jc2

The OP also stated that the fault also occurs at cruise as well as idle which makes the concern more likely to be in the throttle system than the brakes.

Reply | Report as offensive | Link
Thu 25 Nov 2010 16:15
Ford Mondeo - Takes about 1 second to accelerate from the lights - injection doc
and his auto box sticking in gear to max RPM, when the brakes are applied the fly-by wire shut down will prevent the autobox changing up.

He has one weird fault which the dealer should make more of an effort to find.
Reply | Report as offensive | Link
Sat 27 Nov 2010 06:01
Ford Mondeo - Takes about 1 second to accelerate from the lights - andymcgill

Thanks injection doc,

As an electronics techo, I understand fly by wire but not the brake interaction. The brake switch/circuit certainly rings a bell as the fault mostly happens when I brake to stop and then accelerate. This doesn't explain the other faults so maybe I have more than one fault.

I thank all of you for your help as your info will arm me the next time I take it back to the dealer.

Andy

Reply | Report as offensive | Link
Sat 27 Nov 2010 08:29
Ford Mondeo - Takes about 1 second to accelerate from the lights - jc2

On this and most "drive by wire" throttle systems,the module receives a signal from the braking circuit-usually by an output from the brake light circuit and when this is received,the engine is switched to only enough fuel for idle-thus you cannot accelerate and brake at the same time as you could with a mechanical throttle-occasionally needed to dry brakes etc.As I said earlier,it sounds like a fault in the throttle system.

Reply | Report as offensive | Link
Sat 27 Nov 2010 11:31
Ford Mondeo - Takes about 1 second to accelerate from the lights - andymcgill

Thanks jc2,

It looks like I have two separate faults. The brake and the throttle.

Reply | Report as offensive | Link