Rough idle (hunting) loses power (stalls) and now sudden acceleration!

[mrdstamp]

Hi there,

 

I'm new on here.

 

Firstly I am not a qualified mechanic, but not afraid to get stuck in. [emoji3526]

 

I have been having issues with my Ford Focus 2009 1.6 zetec (petrol) for over a year now and I would be truly grateful if anyone actually knows the Solution. Its so bad that I'm now not comfortable driving it with my young family.

 

The symptoms are the following...

 

Hunting on idlle when the engine is switched on which leads to stalling)

 

Jerky shuddering when accelerating from stationary.

 

Poor torque when in third gear.

 

Sudden acceleration when I travelled at 60 when I came onto a motorway (last night of which I noted the time on the car's clock)

 

When waiting at lights/roundabouts car stalls.

 

So far the following has been done...

Spark plugs changed

Air filter replaced

oil changed

 

2 garages have run diagnostics and found no faults.

 

Air manifold block taken out and checked by the garage.

 

There's no Maf sensor in the vehicle because of its model.

 

The Tmap sensor was checked by the garage

 

The inboard computer (forgive me I don't know the term) was reset because the manidold block was taken out.

 

I have absolutely no idea as to how this has happened. The car is shy of 100 thousand miles on the clock (10 000/ year).

 

Limited funds but I really need this fixed for family travel.

 

Thankyou kindly in advance.

 

Dave

 

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[0shiny1]

Could it be a fault with the fly by wire accelerator pedal? 

I've had one go in a tranny connect van before, one moment fine then it became very erratic a bit like how you described.  From what I understand (not much lol) the pedal has a potentiometer which sends a position signal through wires to the ECM  telling the throttle body to open/close at the correct position, that sensor in the pedal can wear out and fail causing similar symptoms.  Worth looking into if they say nothing wrong with the engine.

[isetta]

Yes, on modern cars the throttle is a potentiometer (like a volume control on an old radio). I do not know on what year Focus it became like that (my 2001 focus 1.6 petrol had a traditional cable throttle). But my understanding is that , for safety reasons, the electronic throttle has two potentiometers in it and the 'computer' in the car compares the two signals and if they are not the same it creates a fault code and puts it in limp mode.  But I can't help on what tho do to fix the problem

[0shiny1]

1 hour ago, isetta said:

Yes, on modern cars the throttle is a potentiometer (like a volume control on an old radio). I do not know on what year Focus it became like that (my 2001 focus 1.6 petrol had a traditional cable throttle). But my understanding is that , for safety reasons, the electronic throttle has two potentiometers in it and the 'computer' in the car compares the two signals and if they are not the same it creates a fault code and puts it in limp mode.  But I can't help on what tho do to fix the problem

True it should throw up the engine check light if the TPS detects a difference in the values, my 2003 Transit Connect never did show the ECL for some reason, a few of times I remember pressing the accelerator and it went from a delayed no response to go which was pretty dangerous, it also stalled on a few occasions.   

Could be a number of things OP, did they check the throttle body out?  A bad throttle body might also cause those problems symptoms-of-a-bad-or-failing-throttle-body 

[mrdstamp]

True it should throw up the engine check light if the TPS detects a difference in the values, my 2003 Transit Connect never did show the ECL for some reason, a few of times I remember pressing the accelerator and it went from a delayed no response to go which was pretty dangerous, it also stalled on a few occasions.   
Could be a number of things OP, did they check the throttle body out?  A bad throttle body might also cause those problems symptoms-of-a-bad-or-failing-throttle-body 

Hi there,

They did. The mechanic said they took the throttle body out and found no issue with it. They cleaned it. They checked the sensor attached to it. Then after stocking some redex in the fuel and resetting the ECU they state that there were no issues.

I'm struggling to understand why I still have this issue. It stalls almost daily. When either coming to a junction etc so I quickly have to restart the engine. It also stalls when setting off and in both cold and warm starts. It's sluggish when Gears are changed. I love my focus as it's just used like a "thunderbird 2" but the missus can't rely on it and so won't drive it.

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[0shiny1]

2 hours ago, mrdstamp said:

Hi there,

They did. The mechanic said they took the throttle body out and found no issue with it. They cleaned it. They checked the sensor attached to it. Then after stocking some redex in the fuel and resetting the ECU they state that there were no issues.

I'm struggling to understand why I still have this issue. It stalls almost daily. When either coming to a junction etc so I quickly have to restart the engine. It also stalls when setting off and in both cold and warm starts. It's sluggish when Gears are changed. I love my focus as it's just used like a "thunderbird 2" but the missus can't rely on it and so won't drive it.

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My knowledge is pretty basic so I can't offer much help but you'd expect an engine to behave that way if there's something wrong with the air to fuel ratio (your mechanics already know this so they must've checked everything but might've missed something).  If there's a vacuum leak at the intake (which can cause the same symptoms) they can be hard to spot, maybe your mechanic hasn't checked for vacuum leaks or checked once and didn't find any?  A leak can easily be missed.  Did he put a new gasket on the inlet when he reinstalled ?  Have a good read through this article as it explains it all quite well: manifold-gasket-leak-symptoms

Hope you get to the bottom of it soon, sounds like a right PITA.

[mrdstamp]

My knowledge is pretty basic so I can't offer much help but you'd expect an engine to behave that way if there's something wrong with the air to fuel ratio (your mechanics already know this so they must've checked everything but might've missed something).  If there's a vacuum leak at the intake (which can cause the same symptoms) they can be hard to spot, maybe your mechanic hasn't checked for vacuum leaks or checked once and didn't find any?  A leak can easily be missed.  Did he put a new gasket on the inlet when he reinstalled ?  Have a good read through this article as it explains it all quite well: manifold-gasket-leak-symptoms
Hope you get to the bottom of it soon, sounds like a right PITA.

Thanks for this. I'm very grateful for any advice anyone can give me. I'm going to stick my car in at the end of the month when I get paid. I do wonder how much these things are going to cost, but I still believe the car's worth a bit of TLC. Hopefully I can report back soon. Cheers.

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[0shiny1]

No problem just hope you get it sorted in the end and it would be great to hear back if you do fix it for anyone else having the same problems.

Here's a video which may shed some more light: https://www.youtube.com/watch?v=qTzDY95aqXg