Mk3 TDCI emissions

[allmightyASTON]

Greetings to everyone,

A few days ago, I shared my experience with my emission MOT failure and the following pass achieved by directing vape smoke over the sensor.

I am seeking clarification about my concerns. I have misgivings about the existence of any problem.

The VIN plate indicates 156; does this refer to smoke density, CO2, or NOX? Uncertain and rather irrelevant. Historically, the vehicle has consistently passed the emissions test on the Fast Pass assessment. It failed just once initially, but the second two attempts resulted in an average below 156.

Last year, it achieved a score of 85 on Fast Pass.

This year, a failure with a score of 365! In the weeks before the MOT, I often deplete the petrol and add a can of injector cleaning to the tank; but, for unspecified reasons, I neglected to do so this year. I also do high-rev, full-throttle acceleration tests and monitor for smoke. Indeed, there were some issues before; nevertheless, during this MOT, nothing was apparent in the rearview mirror, which led to my astonishment at the significant failure.

What factors might lead to a shift from 85 to 365 inside a single year? I replace the oil every 5,000 miles; there are no fault messages. The diesel engine is quite loud, but there is no discernible rattling, unless one has my wife's acute hearing. Obstructed injectors? Surely, they would provide some other indication? I believe the miles per gallon is somewhat reduced now; nevertheless, if excessive gasoline is being injected, it should result in smoke or irregular operation. The injectors may need an update, and excessive leak-off might be present; but, would this alone account for such high emission readings?

Considering the dubious method they used to circumvent the emissions test by using vape smoke, I speculate if they compromised the emissions by directing cigarette smoke at the sensor in my absence, then proposing to clean the intake manifold for £250 with a guaranteed pass.

Your insights about the factors contributing to this emission increase would be valued.

Thank you and farewell.

[DreamCatcher88]

I believe there is a missing decimal point in your calculations. The measurement you are referring to pertains to the opacity of the smoke emitted from the exhaust. The default MOT value, in the absence of plate information, is 3.0m-1; however, your plate indicates a value of 1.56m-1, which is the measurement the MOT tester should use.

A high reading might result from several potential reasons, including over fuelling. However, it may just be the testing apparatus of that specific garage. I would not be concerned until you see a significant rise in black smoke from the exhaust or until the next MOT is due (assuming you still own the vehicle).

[allmightyASTON]

You are quite accurate; I acknowledge my error. 1.56 and 0.85 from the previous year. Nonetheless, I am pursuing a resolution to the very high reading. It is possible that the cylinders and piston rings have completely deteriorated during the past 6,000 kilometres. However, I believe otherwise.

Prior to doing the vaping trick, he recommended that I eliminate the 1.56 using sandpaper.

[DreamCatcher88]

Indeed, removing the plate value is a recognised technique.

One may accelerate their vehicle down the road, have the emissions evaluated at a separate garage, and get an entirely disparate result. I am uncertain about the fees charged by garages for emissions testing; nonetheless, obtaining a second assessment may be advisable prior to initiating repairs.

[allmightyASTON]

I have considered this, but I am uncertain about the need of the expenditure. A few cans of Redex diesel cleaner would undoubtedly represent a superior investment.

[coolguy]

Even if you had destroyed the figure on the VIN plate, it would have still failed as the reading exceeded 3 regardless. Should a leak-off test reveal that one injector exhibits a somewhat greater rate than the rest, it may be the source of the excessive smoke. Occurred on my property a few years ago. Alternatively, have SWMBO crank the engine as you monitor the exhaust, and sequentially disconnect each injector to see whether any specific injector significantly decreases the smoke output. I performed the procedure on my daughter's Modus due to one injector exhibiting excessive fuel delivery. Identified the perpetrator by that method.

[allmightyASTON]

Promising concept; yet, ...

There is little smoke; in fact, it is almost imperceptible. Smoke only occurs after I have not accelerated in third gear for an extended period; however, after a few bursts of speed, it dissipates completely, even in the headlights of the trailing vehicle. At the MOT, the vehicle is idled for 10 minutes before to the test, which may result in some smoke during the first acceleration.

[torque2me]

My Mondeo consistently exhibited low emissions; initially, I recorded 1.43 and 1.11 on two separate occasions. Subsequently, I disabled the EGR valve and removed the catalytic converter, resulting in a reading of 0.33 on the first rev. All of this was accomplished at the same motor station.

[allmightyASTON]

My ERG is disabled, but the catalytic converter has been removed. Does that include the removal of the cat?

[torque2me]

It does not possess a 'cat' per se, as I have previously read, but rather a spark suppressor mechanism. Can someone currently living verify this? 🤔

[alabbasi]

I believed that pertained to a DPF in diesel engines. comparable to a feline.

[torque2me]

It is possible that later 2.2 vehicles were equipped with a diesel particulate filter.

[VVC-Geeza]

The DPF on the MK3 is quite uncommon. Typically, just the CAT.