Hello all. I've got 55 plate focus 1.8tdci and having some issues.

From a cold start the car will buck and jerk at around 1500 RPM but goes once at running temp. Other symptoms are when I let off the accelerator it seems to hold the revs for a second. And my MPG is completely down. Also have fault code P141A - EGR electrical fault. I've changed the actuator and checked wires and connections and all seem ok. Also tried a blinking plate on EGR but no change.

One forum lead me to it being a throttle position sensor issue. However I cant find anything on it at all. Any help would be great

1 hour ago, Stuart1990 said:

a throttle position sensor issue. However I cant find anything on it at all.

A 1.8TDCI has no throttle at all. Only the 1.6TDCI & 2.0TDCI have anti-shudder or throttle valves. It could mean the accelerator pedal position sensor (APP), but the symptoms don't really match this.

The APP is a dual sensor, and will give fault codes if the two sensors mismatch. Also it is not part of the engine, so is unlikely to respond repeatably to the engine being at running temp.

I am not sure if your car is Mk1 or Mk2, I think 2005 could be either. I have done a lot of work on my mk2 EGR, including changing the actuator, but P141A was never one of the faults I had. Possible causes are a faulty position sensor in the EGR actuator, including a faulty replacement (can't rule this one out, as I think all the replacement actuators are Chinese, and quality can very), faulty wiring to the position sensor or to the EGR motor. Faulty MAF.

The MAF is a key part of the way the ECU controls and monitors the EGR flow, so if it is faulty, the ECU could see this as a faulty EGR. Bad MAF will also affect fuel economy and maybe control of rpm.

The MAF can be disconnected. It will raise a fault code, but the ECU will continue to try to operate the engine using default values, which can help identify a bad MAF somrtimes.

A report on my EGR and how I tested it is here:

 

Hi Peter. Thanks for the response. Mine is the mk2 with the duratorq engine. 

Is the APP part of the accelerator pedal on these do you know? 

I will investigate the MAF sensor and see what I find.

Thanks again

10 hours ago, Stuart1990 said:

Is the APP part of the accelerator pedal on these do you know? 

Yes, the APP is part of the pedal assembly, all inside the cabin under the facsia. To get at it, remove the lower fascia trim panel, and it is fixed to the bulkhead by 3 bolts.

A good diagnostic system like Forscan can test the APP, you can view the signals in real time. But I would say an engine problem like MAF or the fuel system is more likely to be the cause here.

Tried disconnecting MAF sensor and car wouldn't start. Put a different one and same issue so back to the egr. Unfortunately I cant get my hands on good diagnostics system. 

1 hour ago, Stuart1990 said:

I cant get my hands on good diagnostics system. 

Forscan costs about £16 for the ELM327 adapter, and free download of software for Windows, or small charge for iOS or Android Apps. It is probably the best available DIY system for Fords, only the Ford IDS system can beat it, usually.

A possible source for the adapter is: https://tunnelrat-electronics.fwscart.com/

Severe bucking and jerking sounds like something more than the EGR valve, especially as a blanking plate has been tried. Air in the fuel could possibly do it. Has the fuel filter been changed recently? A clogged filter will not help, or leakage through the seal on the filter housing could allow air in. There is no tank pump, so most of the system is under some suction all the time, even more so if the filter is getting clogged.