I’ve recently had a problem with my mk2 focus rs when it comes to boosting. About 3 months ago I had a problem where the car was jolting and hesitating under heavy boost but eventually got it fixed (turned out to be the turbo actuator). It’s been running fine since then but there has been another problem that has appeared seemingly overnight. When I put my foot down and apply boost the car misfires rapidly sounding like a machine gun coming out the exhaust. It happens nearly every time I accelerate using any turbo and started very suddenly. Sometimes it won’t misfire but will restrict itself on boost to about half gauge. Also when sitting at idle from a cold start the revs will climb to about 3k for a second or so on its own without me touching the pedal. However, the misfire on acceleration goes away when I unplug the maf sensor but I only had a new sensor when I had the car fixed about 3 months ago. I also had new spark plugs and had the cylinders pressure tested (all good). The engine management light has come on and flashes sometimes if I try to accelerate through the misfire. Could do with some help as I'm not too knowledgable with cars I just like to drive them! Thanks.

It would be a good idea to get the fault codes read to better understand what the problem might be. 
 

If you need expert advice try speaking to Gary at Collins Performance, he’s an RS expert 👍

Have you ever found the causes.of.the misfire?

1 hour ago, evandro said:

Have you ever found the causes.of.the misfire?

One Post Wonder (OPW)

Hi I have a mk2 Ford focus rs the parking sensors stopped working I have replacing the odd one before but the ticking noise you listen out for isn’t in any of them so there must be a bigger problem than a dodgey sensor.

i have followed a YouTube video on how to change the reverse switch it says the switch is under the gearbox mount but I have got to where you take the mount off but the switch is no where to be seen does anyone know where is could be? Or if it’s not even the switch what was it could be?

Is it not next to the gear selector arms as per this video?

If it’s the reverse switch at fault are you seeing an issue with the reverse lamp at the same time?

1 hour ago, troy45 said:

Is it not next to the gear selector arms as per this video?

If it’s the reverse switch at fault are you seeing an issue with the reverse lamp at the same time?

The reversing light is still working as normal which is why I didn’t think it would be the reverse switch but I thought If I could at least find the reverse switch I could test to see if it was still working or not but from the YouTube videos it doesn’t seem to be where they say it is  

Just now, Ricksy said:

The reversing light is still working as normal which is why I didn’t think it would be the reverse switch but I thought If I could at least find the reverse switch I could test to see if it was still working or not but from the YouTube videos it doesn’t seem to be where they say it is  

It is not near the gear selector arm I couldn’t see it at all once I had taken the gearbox mount off 

All the links I’m seeing on the web for the RS, and ST have it in the same place under the gearbox mount next to the gear selector arms. 
 

Even checking specific RS forums gives the same removal process etc

https://www.focusrsoc.com/threads/how-to-change-a-reversing-light-switch.72162/#post-1159938

As an alternative check for the switch working if you have the front wipers on and put it in reverse the rear wiper should operate, unless you’ve got that disabled like I think I did long time ago.

If the reverse lights are working then the switch is not at fault.

Use FORScan and read the Ford specific DTC's.

The only other thing I could think of would be the module but I am unsure about this, I have checked numerous videos of the reverse switch being changed on also an st and your right they seem to be roughly in the same position but on mine there is nothing at all can’t exactly miss it which is why I am puzzled by where it could be but I don’t think this is the fault as the reverse light still comes on but all 4 sensors are not working and none of them tick. 
I very much doubt all 4 sensors went at exactly the same time 

8 minutes ago, Ricksy said:

The only other thing I could think of would be the module but I am unsure about this,

It's far more likely than a reverse switch which is still working for the reverse lights.

At the risk of repeating myself, just use FORScan and read what the diagnostic trouble code is. It will take away the need to guess, and save time and money.

Sorry if I am being thick but Forscan?

Yep, suspect the Park Aid Module (PAM) 

14 hours ago, Ricksy said:

......but Forscan?

FORScan = Diagnostic Software for Ford vehicles.  Able to read the Ford specific Diagnostic Trouble Codes (DTC's)

On 4/7/2024 at 8:59 PM, unofix said:

FORScan (for use with Windows Laptop) : https://forscan.org/download.html

It's what many Ford owners use including some Ford technicians.

vLinker FS, cable for laptop: https://www.amazon.co.uk/Vgate-vLinker-Adapter-FORScan-MS-CAN/dp/B0952P4MLP

vLinker FD, for android phone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H82WC8L

vLinker FD+, for iPhone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H8JHWP2

 

Search Tag:   FORScan123