Throttle body relearn procedure on 1.4 tdci

[5tefan90]

Hi I'm new here ! I have a 2007 fiesta 1.4 tdci. Very randomly it has a slight stutter on acceleration or on a hill, then it went into limp mode (flashing orange exclamation mark) turned off the car for a min then was ok, now when I start the car in the morning it idles rough until it reaches temperature. I have changed oil, oil filter, diesel filter, MAF sensor, Intake temperature sensor, run injector cleaner in it too. I'm going to clean the throttle body next and was wondering what the procedure is for the TB to relearn it's values, maybe this might cure cold rough idle ?? Also I will clean the EGR valve.

Any thoughts would be much appreciated and if anyone knows the procedure for the TB please let me know.

 

Regards 

[Tdci-Peter]

39 minutes ago, 5tefan90 said:

it went into limp mode (flashing orange exclamation mark)

There would have been error codes stored if a warning light came on, for certain. A good diagnostic system like Forscan (about £16 with a Windows laptop, or £20 -£25 for Android or iOS) would reveal any codes present, and might help narrow the problem down.  Also, if there is a Throttle body relearn procedure, then Forscan will be very likely to have it.

The throttle body on a diesel does not do the same job as on a petrol engine. Most of the time it can be wide open, the engine runs lean. Only the fuel needs to be controlled. My 1.8 has no throttle valve at all. I suspect that on the 1.4, it is used in conjunction with the EGR valve to boost the EGR flow when needed. It may also be used in conjunction with DPF regens if the car has a DPF. I doubt if the throttle valve will be the cause of rough idle here.

Faulty or sticking EGR valves can certainly cause hesitations, usually under moderate power. Near full power the EGR is fully closed, for maximum oxygen. I have had hesitations on pull-away with my car, which was an electrical fault in the EGR. It also put a warning light on at times, with EGR DTCs stored. It never gave so called limp mode though. But really it needs the DTCs to be read to get anywhere without endless part swapping.

[5tefan90]

Hi Peter yes I have a obdII tool that connects to my phone it gave me MAF and IAT faults and after the incident with the yellow exclamation mark it had a misfire fault on cylinder 3 (see screenshots for codes) i thought the misfire could be caused by either a faulty MAF or IAT by not telling the car what air to fuel mixture is optimum but since I have changed these parts I still get rough cold idle and hesitation ( no misfire as of yet. Thanks for clearing up about the TB but could it still be worth a clean and disconnect the battery for a while ? I will definitely have a good look at the EGR tomorrow and try giving it a good clean. 

 

Regards

[5tefan90]

Just to add, I have no more fault codes  and have been driving for over 200 kilometers. But still rough when cold and hesitation issues. There's nothing to point me in the next direction! Before maybe changing injectors but they are the most €€ thing on the list.

[Tdci-Peter]

57 minutes ago, 5tefan90 said:

But still rough when cold and hesitation issues. There's nothing to point me in the next direction! Before maybe changing injectors but they are the most €€ thing on the list.

When I read about hesitation, injector problems did cross my mind, but as you say it is the last thing to change, after all other checks. It might be worth removing and cleaning (eg with contact cleaner) the plugs on the injectors, as it shows it as an electrical open/short fault.

Cleaning the EGR & throttle valve would also be worth doing before considering injector problems other than a simple bad connector.

Optimum air/fuel mix is not important on a Diesel except at full power, when too much fuel just makes smoke. It normally runs very lean. A throttle valve that is normally part closed actually wastes a lot of power, and hence wastes fuel, one of the 3 reasons why Diesel is more efficient than petrol. But sudden EGR or throttle jumps will cause small hesitations as the measured air flows jump about, and the ECU tries to compensate.

With multiple faults indicated, it is hard to be sure what is real. A faulty IAT will make the MAF appear to read wrongly, so could cause the MAF performance error. EGR and throttle errors can also lead to MAF reading oddly. This is because the ECU compares computed engine airflow using RPM. MAP & IAT with the MAF readings. Engine airflow includes exhaust recirculation (EGR), MAF is outside the recirc loop, so does not include EGR. The difference between computed engine airflow and MAF reading is hence (ideally) the EGR flow, and this is used to control the EGR valve to the correct flow rate. With such a complex closed loop, working out what is cause and what is effect is almost impossible!

Blanking off the EGR may cause the MIL to light, but is still a good way to verify if the EGR is causing the hesitations. I did this several times on my car before finally finding a sensible priced new actuator unit to cure the faulty EGR.

[5tefan90]

I have cleaned the connector's to the injector's and the seals looked dry. I will attack the EGR tomorrow. When you say actuator unit is this part of the EGR valve ? 

I appreciate you taking the time to explain how all this works ! I'm not a mechanic but I am fairly technically minded !! 

Regards

[Tdci-Peter]

10 hours ago, 5tefan90 said:

When you say actuator unit is this part of the EGR valve ? 

My car has an electric actuator which is bolted on to, and normally regarded as part of, the EGR valve. (Not relevant here!, but one bad point on the 1.8 is that the EGR is built into the inlet manifold, and is a monstrous job to remove, but the actuator is easy to remove.)

The 1.4 seems to have two options, vacuum or electric. The difference is quite obvious:

https://ford.7zap.com/en/car/54/no/13/1549/15357/

Electric is self-contained actuator and valve. Vacuum will use a remotely mounted solenoid valve piped to the brake servo vacuum line. The part of the actuator on the valve is just a diaphragm unit. Dodgy solenoid valves on vacuum EGRs are quite common.

An electric actuator is normally just a basic electric motor, and a position feedback device which is usually just a basic mechanical potentiometer. It will have 5 (used) pins in its connector.

[5tefan90]

Ok so cleaned the EGR valve it was pretty caked up and could of possibly been a little stuck open, but still have the rough cold idle, give it some revs for a min And it smooths right out and idles perfectly. 

What could be causing a rough cold idle ?   

See pictures of EGR 

[Tdci-Peter]

1 hour ago, 5tefan90 said:

What could be causing a rough cold idle

Glowplugs.

Common rail diesels can start even in quite cold conditions without them, but still run rough until warmed up a bit.

Check power to the plugs (fuse & relay), then, if possible the resistance of each one. They register as a virtual short circuit (under 1 ohm) on a multimeter, so can't be tested if wired together.

Also check if the hesitations have gone away. It would be very good news if the dirty EGR was the cause of those.

[5tefan90]

Ok thanks Peter I will let you know how I get on ! 

[5tefan90]

18 hours ago, Tdci-Peter said:

Glowplugs.

Common rail diesels can start even in quite cold conditions without them, but still run rough until warmed up a bit.

Check power to the plugs (fuse & relay), then, if possible the resistance of each one. They register as a virtual short circuit (under 1 ohm) on a multimeter, so can't be tested if wired together.

Also check if the hesitations have gone away. It would be very good news if the dirty EGR was the cause of those.

Hi again ! Do the glow plugs only kick in when the outside temperature is VERY cold ? I live in Spain and yes the temperature has dropped at night but no where near -0° and I can't find the fuse for it behind the glove box,it's not even on the picture on the back of the glove box but it is in the ford manual. I get no glow plug light when I turn the ignition on but when I did a LED test it was there. I've also heard that they can be a nightmare to remove a lot snap off inside the block and then it gets €€€. Do you know where the location of the glow plug relay is ?  Regards

[Tdci-Peter]

2 hours ago, 5tefan90 said:

Do the glow plugs only kick in when the outside temperature is VERY cold ?

Normally they come on for engine temperatures below about 20C, that is the case on my car. Though they are not needed until somewhere between 4C and 10C. You should be able to detect glowplugs coming on by a drop of about 0.5v to 1v in the battery voltage. They take 30A to 60A. The fuse will be a big boltdown job, 60A typical. May be tucked away down one side of the battery or down one edge of the fuse box, almost certainly in the engine bay.

I have had trouble before in finding fuse info published on the Mk6 Fiesta, lots on the Mk7 & later, but very little on the 2002 to 2008 models.

[5tefan90]

Quick update, think I have sussed out where the bad cold start is coming from.

The fuel lines under the airbox probably have a small split in there somewhere from where I was cleaning the injector connectors, air seeps into the pipes over night and then starts rough the next day. I'm waiting for ford to sell me the parts as they are on order. Will update when installed.

[Rushy]

Hi.  Did you get a solution?  My fiesta is rough on cold days and hesitates when gently accelerating about 2000rpm.  Did cleaning the egr help with the hesitation?