Blocked DPF

Removing a Blocked Diesel Particulate Filter (DPF)

Removing Common Rail Diesel DPFs can be a labour intensive job as some particulate filters are part of the catalyst and therefore part of the exhaust manifold or front pipe assembly. These are often fitted as close to the engine as possible to help maintain a high temperature and to assist fast warm up. V6 and V8 engined vehicles may have two DPFs and are often even more difficult to work on due to obstructions like steering racks, sub frames and turbochargers etc., restricting access to exhaust manifold nuts or bolts. Older vehicles can present even more problems due to corrosion or seizure, in some extreme cases making it necessary for the garage to use oxy-acetylene burning equipment to remove the DPF.

DPF Core Removal – Before

DPF Core Removal – Before

DPF Core Removal - After

DPF Core Removal – After

After removing the DPF it will be necessary to either fabricate or purchase a replacement by-pass pipe ensuring that any exhaust pressure and temperature sensor take-off points are retained.

DPF - Core removed

Eyeing-up the job – Refitting

Where possible, CRD Performance will remove the DPF assembly, empty its contents and seam weld it back together so that it still appears fully intact.

With the DPF now removed the engine management system still monitors its DPF pressure and temperature sensors to check they are present and working.

Without this, the ECU will detect an error, switch on the engine management light and enter ‘limp’ mode, rendering the vehicle almost undriveable.

Software Upgrade (aka DPF Deletion)

If the Diesel Particulate Filter is physically removed from the exhaust system and the ECU not remapped to accept the changes, then sooner or later the engine management system will go into ‘limp’ mode, or LOS (Limited Operating Strategy). When in limp mode the vehicle may have restricted power and, if fitted with an automatic transmission, it may even lock into top gear to limit acceleration.

While monitoring ‘pre’, and on some vehicles ‘post’, DPF differential pressures, the vehicles’ management system monitors the current state of the DPFs and detects if one or more are present. Software DPF removal involves reprogramming the vehicle’s ECU to ignore any abnormally high or low readings from either the pre or post DPF differential pressure sensors. As previously mentioned, it is still necessary for all DPF pressure sensors to be present and working. Software changes can only be made to open up pressure monitoring parameters, preventing regeneration, not to ignore the sensors altogether.

Software Power Upgrades

Some customers, while having their ECUs re-programmed to delete the DPF, take the opportunity to have their engine re-mapped for additional power, better driveability and better fuel economy. CRD Performance use several engine remapping companies for this purpose, who offer a discount if both programmes are carried out at the same time at our workshop in Bolton.

DPF Emulators

On some vehicles, software DPF deletion is not possible; this is especially true for some Japanese and Asian vehicles. CRD Performance now have available a full range of emulators which are programmed specifically for each vehicle make and model. Installing these does not involve interfering with the vehicle’s ECU since the emulator is instead wired into several of the engine sensors. These units work by fooling the cars ECU into believing that the DPF is still present and maintained in a clean condition, therefore not requiring any regenerating, even though it has in fact been removed.

Beware of cheap DPF Removals

We frequently have vehicles brought to us in Bolton to correct a previous attempt to remove a DPF that has gone horribly wrong. Often the vehicles are in an undriveable condition, stuck in ‘limp’ mode, with the engine management light on, yet no fault codes present.
Be very aware of cheap quotes – you have been warned! “Cheap today, dear tomorrow”.

CRD Performance is the North West’s leading DPF removal specialist, providing DPF removal services for all Lancashire and Greater Manchester districts, including Manchester, Liverpool, Warrington, Blackpool, Bolton, Stockport, Preston, Blackburn, Oldham, St Helens, Chester, Rochdale, Southport, Birkenhead, Wigan, Burnley, Salford, Crewe, Wythenshawe, Ellesmere Port, Runcorn, Bury, Bootle, Wallasey, Huyton, Widnes, Sale, Macclesfield, Lancaster, Middleton, Stretford, Ashton-under-Lyne, Leigh, Swinton, Urmston, Walkden, Altrincham, Leyland, Skelmersdale, Eccles, Accrington, Darwen, Denton, Radcliffe, Tyldesley, Chorley, Chadderton, Prestwich, Hyde, Wilmslow, Winsford, Reddish, Northwich, Nelson, Ashton-in-Makerfield, Heywood, Fleetwood, Kendal, Whitehaven, Farnworth, South Turton, Workington, Formby, Saddleworth, Marple, Hindley, Ormskirk, Whitefield, Droylsden, Golborne, Westhoughton, Congleton, Stalybridge, Clitheroe, Rawtenstall, Penwortham, Royton, Failsworth, Colne, Little Lever, Little Hulton, Great Lever, Kearsley, Horwich and Worsley.

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