Ford Focus 1.5 EcoBlue ST-Line X - Diesel Auto - Car jerking and juddering

[Alis]

Hello,

I have recently bought Ford Focus 1.5 EcoBlue ST-Line X Diesel Auto. I have noticed when the car is cold the it runs fine and smooth. As soon as the car warms up it gets into severe jerking and juddering at low speed (city driving). I have to let go of the acceleater and repress it again to make it run properly (sometimes it works) other times i have to press the gas pedal hard enough and at higher speed of acceleration it runs fine. 

How do i go about trying to figure out what could be the issue causing this? Any tips or pointers to get started would be really appreciated.

[mjt]

First I would check for DTCs using Forscan. @unofixwill tell you what's needed. Without the codes you'd be 'flying blind' and end up throwing money at it.

[DaveT70]

How many miles has the car done?

I presume you are an early MK4, not a late MK3.5?

Early MK4s had software issues.

Ensure the main 12v battery is in good condition

Get the fluid level and condition checked ASAP, take the car to Ford and ask them to update the software in the PCM (Engine ECU) and the TCM (transmission ECU) to the latest level (The PCM/TCM maybe combined) , ask them to reset the adaptive shift learning and perform a relearn drive cycle with you.

This will cost you a couple of hours labour, but will be worth it

[Alis]

@mjt - i got the forscan and have the fault codes, i'll post them down below.

@DaveT70 - The car is a MK4 (68 REG late registration, shows in the Ford app as a 2019 Ford Focus) with 94k miles on the clock also thanks for the advice would you know how much it cost to update the PCM and TCM and resetting adaptive shifting learning would cost at the dealers?

So after plugging in the Forscan today i found a couple of fault codes listed. 

PCM - P06E9:00-2F - Engine Starter Performance = I think this has to do with the starter motor i noticed at times the car makes a high pitch noise when starting. The sort of noise it would make when the starter motor is slipping or on the way out. I am not sure if it would make the same noise if the ground on the cars are not connected properly. (any idea where all the grounds are on this ford focus)

PCM - P049B:9C-64 - EGR B Flow Insufficient Detected

PCM - P24C7:00-64 - Particulate Matter Sensor Temperature Circuit Range/performance

Is there a way using Forscan to check if the sensors are working fine for the above two PCM codes (P049B,P24C7) and if they are faulty i could replace them.

Also in terms of diagrams, guides what is the best manual out there for a MK4 that i could get which can aid in helping troubleshoot issues with the car.

[DaveT70]

You can use Forscan to reset the adaptive shift learning, search google for 6F35 (I know!) adaptive shift relearn drive cycle, follow that - TO THE LETTER

If you are brave and have a paid license, you can use Forscan to update the PCM/TCM

As you are at 90,000 I would strongly recommend changing the transmission fluid some of those codes might be due to poor battery performance.

[Alis]

I have so far completed the adaptive shift learning reset 6F35 which did not result in any improvements. I have also replaced the EGR Valve too and that didn't help either. I noticed that i am only getting around 19-20 MPG while driving hence think its a fuel/air mixture issue or some kinda a blockage at some point.

Still getting the PCM - P049B:9C-64 - EGR B Flow Insufficient Detected

What could be the next diagnostics steps?

[Alis]

Update: Found using the diagram on the Engine Emission Control -  Exhaust Gas Recirculation (EGR) Cooler to EGR Valve Tube was a mesh filter that was clogged up. Changed the filter (£13) and that solved the issue.