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Emissions very high

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3 hours ago, frund said:

Confusing indeed.


This Fiesta seems to be Euro 6, with very low specified PM emissions (0.005g/km, vs 0.025g/km for Euro 4). I assume it has a DPF, so how all the smoke gets through that is a bit of a mystery. Unless the matrix is cracked or damaged.

Another problem is the MoT test is for smoke in units of m-1, not PM. And done unloaded at high rpm, not over a simulated drive cycle. I have just been glancing through a rivettingly exciting document :yawn:laugh.png:

http://www.transportoffice.gov.uk/crt/repository/Low Emission Diesel Research - Annex 4.pdf

There is almost no correlation between the MoT test limits and the PM limits in the Euro standards!

But that aside, it did have one interesting paragraph:

"A number of franchised garages, for different OEMs, were surveyed to find the most
common faults encountered by modern diesel passenger vehicles.  The consensus list
•      faulty air mass meter (noticed by customers as a reduction in power and sometimes
increased smoke)
•      faulty pressure or temperature sensors
•      EGR faults (usually a stuck valve)
•      faulty throttle position sensors (usually badly fitted rather than broken)
•      injector faults (usually caused by contaminated fuel rather than faulty units) and
•      all the garages surveyed said that ECU faults are very rare."

Top of the list is MAF. On many cars a simple test for a dodgy MAF is just to disconnect it. Then the car is not misled by the faulty readings. It will put the EML on, but usually does not lead to a reduced power mode.



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I like the idea of looking hard at the MAF. This does seem to be in control of the air to fuel ratio somewhere along the way. Could this be the Culprit. Seems to only smoke after tick-over but I could be wrong. Initially when the MOT tester revved up the eng there was a cloud of black smoke this is still there. 

i will disconnect the MAF later on today. 

It seems that whatever the fault is it is definitely there all the time not intermittent so should be easy in theory to fix.....but the modern engine is a bit complicated electronics wise.

Reading last night about faulty / dirty sensors quite a bit of info there. So I would not be worried about removal and spray clean refit. 

At the end of the day my eng would appear to be maybe, overfueling on tick over (it has good mpg), or Lack of Oxygen so not burning all the fuel in the chamber. 

If there was major injector failure my MPG would not be 64 + and possibly rough sounding. My car 'sounds' excellent. Thinking out loud.

One of the problems I have is that I am not at all sure what some of the sensors are doing or even where they are  BUT I am learning.

Thanks for last post Tdci-Peter very interesting and to others for their input all taken onboard.

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I wouldn't expect a MAF to be faulty on a 3 year old car tbh.  

Have I read right that the smoke is there at idle and gets worse when revving?  It sounds like you've got a boost leak somewhere, one of the hose clips has come a bit loose maybe?


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I have disconnected the MAF sensor, Tdci-Peter, and went for a 4 mile run and revved up the engine...still the same quite a bit of black smoke when revving up. Not noticeable at other times like tickover. Filter is clean. A good way to eliminate one sensor.

I will look at Hoses, TomsFocus, these are in a easy position to look at. I may take them off to look for problems.  

Stuck EGR ? no lights on dash and no ford warnings at QuikFit yesterday. I have had a look at where EGR is and probably with a bit/ lot of swearing I could get it off. The pipe from the EGR

to Manifold is soooo tempting to blank, easy to get to  but then lights would come on and maybe limp mode. EGR is supposed to reduce NOx emissions but does, it seems create soot.


Having removed the turb to throttle block,  pipe. Rubber 2" bore or so. see photos earlier, it was noticeably black, sticky a bit of a mess inside with traces of dirty oil.  Could it be the Turbo on the way out?  

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12 hours ago, frund said:

The pipe from the EGR to Manifold is soooo tempting to blank,

Blanking plates are usually cheap, and could be worth it just to eliminate or blame the EGR.

On my car, a badly stuck EGR or faulty actuator will put the EML on, as the valve does not move, or is not sensed as moving, when commanded. But it does not cause limp mode. A blanked EGR causes me no EML or other problems. However every engine version is different, and later engines are likely to be more fussy.

But like Tom says, check the hoses & pipes thoroughly first.

Where does the crankcase vent hose join the inlet tract? It must be before the turbo, and that will always put a bit of oily muck into the pipes. If there is a lot, it is worth checking the oil separator that is usually part of the crankcase ventilation system. I would investigate that before blaming the turbo. A turbo not delivering the required boost should be detected by the MAP sensor, and trigger a DTC, typically P0299, turbo underboost. And the ECU will see this, and cut the fuel to suit.

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thats what your egr valve looks like. only 2 bolts to remove if you want to inspect it


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Just got the posts been away. All the inputs are very helpful indeed. I may be jumping to 'involuntary euthanasia' ( for the car) when the problem is fixable. EGR off for a look is very likely. This would decide if it was stuck or faulty, gunged up.  iantt. (was going to go to Malvern Theater, Cabaret, (2) sold out. bums )

The turbo is not noisy and seems free with no play in the shaft. So I may be totally wrong there to blame turbo as you said above  Tdci-Peter.   I do not like the EGR cycle at all. I feel sure the car would go better without it.

Also reading MPPS v16 stuff which seems to be riveting, possibly in the future. If the program will talk to my ECU. ( not on the model list yet) but may be something there one day.

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