Lumpy acceleration and engine drone
11-09-2009, 11:43 AM
#11
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Checksum - you might also be interested to look for a thread on the EGR thermostat problem that affects the 525d (and others). Basically there is a small, secondary thermostat which is linked to the EGR (exhaust gas recirculation) system. The thermostat can fail - stick open - which means the engine takes longer to reach operating temperature (91 degrees C), or may not reach operating temperature at all. This means your engine is running rich, which means more soot in the exhaust, which means more frequent DPF cleaning, and higher fuel consumption. As there is no coolant temp gauge on the dash you don't realise the car is running cool.
I checked my EGR thermostat at the weekend and it was stuck open, so I've ordered the part (?20 or so).
I checked my EGR thermostat at the weekend and it was stuck open, so I've ordered the part (?20 or so).
11-15-2009, 05:53 AM
#12
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My Ride: BMW 525d SE
Originally Posted by __CA__' post='1050949' date='Nov 9 2009, 08:43 PM
Checksum - you might also be interested to look for a thread on the EGR thermostat problem that affects the 525d (and others). Basically there is a small, secondary thermostat which is linked to the EGR (exhaust gas recirculation) system. The thermostat can fail - stick open - which means the engine takes longer to reach operating temperature (91 degrees C), or may not reach operating temperature at all. This means your engine is running rich, which means more soot in the exhaust, which means more frequent DPF cleaning, and higher fuel consumption. As there is no coolant temp gauge on the dash you don't realise the car is running cool.
I checked my EGR thermostat at the weekend and it was stuck open, so I've ordered the part (?20 or so).
I checked my EGR thermostat at the weekend and it was stuck open, so I've ordered the part (?20 or so).
I haven't noticed the engine taking a long time to get up to temperature though.As to the temperature gauge there is a gauge or sorts, its the dashed lines on the rev counter which start at 4k when cold and slowly moves around to almost 5k when at operating temperature (A proper gauge would have been nice though).
I will get the EGR thermostat checked in the next service though
only 2500 miles away.
02-16-2010, 03:52 AM
#13
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Thanks for the heads up I haven't noticed the engine taking a long time to get up to temperature though.
As to the temperature gauge there is a gauge or sorts, its the dashed lines on the rev counter which start at 4k when cold and slowly moves around to almost 5k when at operating temperature (A proper gauge would have been nice though).
I will get the EGR thermostat checked in the next service though only 2500 miles away.
I haven't noticed the engine taking a long time to get up to temperature though.As to the temperature gauge there is a gauge or sorts, its the dashed lines on the rev counter which start at 4k when cold and slowly moves around to almost 5k when at operating temperature (A proper gauge would have been nice though).
I will get the EGR thermostat checked in the next service though
only 2500 miles away.Will report back with outcome
02-16-2010, 11:09 AM
#14
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Well no conclusion from the garage but the exhaust pressure sensor has thrown a lot of errors in the computer so it could possibly be the problem.
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