Smoking on acceleration
My 2005 Jaguar X-TYPE 2.0 diesel estate smokes under acceleration. It produces a smelly blue-white haze which stops when you lift your foot off the accelerator, suggesting that the haze is mostly unburned diesel. Also, at 50mph at 1600rpm in 5th gear the engine runs jerkily, as if it is near stalling, and it's particularly bad going uphill. If you change down into 4th gear the smoke continues but the jerkiness goes away. Accelerating hard in 2nd gear to 3500rpm produces an initial bluish-white haze that turns to brown smoke, followed by 3-5 miles of relatively smoke-free driving. But it will also on occasion do a ‘soot dump’ under these conditions.
The mileage is 181,000, with full Jaguar dealer history for the first 150,000 miles and subsequently by a local specialist. It has its original engine, gearbox and clutch, but there’s a slight leak from the rear crankshaft oil seal. Fuel consumption is still in high 40s and it does about 50006000 miles per year. The Jaguar specialist could find nothing wrong with the car and said that I wasn’t driving it “hard enough”.
To try and stop the smoke, the vacuum EGR valve was replaced by a Jaguar dealer at 123,000 miles using a Ford-branded one and the fuel injectors were replaced at 178,000 miles after the smoke became excessive. I cleaned the EGR valve at 180,000 miles and also took off the inlet manifold to inspect it internally and replace the seals. There was a light carbon deposit in each section of the manifold but nowhere near enough to significantly block anything. It passed its most recent MOT with a minor defect to the numberplate light bulb and an advisory on rear tyre wear, but no mention of emissions. There are no warning lights illuminated on the dashboard display, but as I do not have a diagnostic reader I can’t check for fault codes.
When I had the injectors replaced, I suspected they'd been at fault because the oil level in the sump maintained a suspiciously high level, and I am aware that these engines are sensitive to high oil levels. I got the specialist to reduce the oil level to ¾ on the dipstick and found that the level rose over a period of time, suggesting the injectors were over-fuelling. This appeared to clear the problem for 1000-2000 miles before the smoke returned, albeit not as bad as it had been. It hardly seems a satisfactory solution to just keep lowering the oil level in the sump to reduce the smokiness!
Assuming the fuel injectors are operating correctly, is the problem that the engine is not receiving sufficient air under acceleration? And would this be a mechanical problem, or could it be that one or more sensors are providing incorrect data to the ECU?
John Osley
The diesel particulate filter regeneration system on your Jaguar operates during normal driving and should not require any input. This is carried out by an injection of fuel into the DPF system during the exhaust stroke and this can have the side effect
of fuel entering the sump and diluting the engine oil. When this occurs the engine oil should be changed before the designated service interval to prevent possible lubrication problems. Given the mileage of your vehicle and the lower mileage that you now carry out, it is possible that the DPF is becoming blocked and the management system is attempting to regenerate it often and without success. This would account for the constant rising of the oil level. With this in mind it may be worth getting the DPF regenerated by a local garage using suitable equipment. However, as your vehicle has been into the local Jaguar dealer, I would have expected this avenue to already have been explored.
Another possibility is that, as you suspect, the injectors are not operating correctly. This may not be a fault with the
injectors themselves, but they may not have been correctly coded when fitting.
You asked about the possibility of a faulty sensor and there is one component that often fails and will not leave a fault code or illuminate the management light: the mass air flow (MAF) sensor. This detects the air flow rate and instructs the ECU to adjust fuel being injected. The sensor can be cleaned using an isopropyl alcohol or dedicated cleaner, but this is not always effective. It should also be noted that if the MAF sensor is cleaned, the engine should not be restarted until the sensor has fully dried.
Finally, Autodata informs me that there is upgraded engine control module (ECM) software available for your X-TYPE, but I hope the main dealer would have attended to this.