Concerns about a recent loss of performance led to me to have a local garage plug in their diagnostic tool to investigate the issue. They couldn't identify any logged problems in the engine control systems but were surprised that the engine idle speed is 1400rpm. Is this normal for the 1.0TSI 115PS engine when warm? I seem to recall that it used to be around 600-800rpm at most but I may be wrong.
MotorMan
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277 Posts
Your description is exactly how I recall mine was until recently but I thought I must be wrong. What is strange is that the 'target' idle speed shown on the diagnostic analyser was also 1400rpm so the actual speed measured is considered to be a 'pass'.
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277 Posts
I managed to find a local VW/Audi tuning/remapping specialist garage who had a look at this high idle speed issue. The outcome is interesting if you, like me, are a low mileage driver.
DPF filters in diesel engines is nothing new but news to me is that the 115 TSI petrol engine is fitted with an Otto Particulate Filter (OPF) to trap soot particles in the exhaust system. If you regularly do high speed, long journeys there's no problem as the soot trapped by the filter will burn off naturally. Unfortunately, pootling around as I do at 40-ish mph in higher gears just adds to the soot build-up. The garage found my OPF was partially blocked which they cleared with a forced OPF regeneration process. Hey presto - the idle speed dropped from 1400rpm to 900rpm when warm. It seems the engine management was keeping idle revs high to compensate for the partially blocked filter.
The car now feels so much better to drive. So take note if you are a careful, low mileage driver. I was advised to hold the engine revs over 3000rpm occasionally to help clear the OPF. Hope this may be useful to others.
DPF filters in diesel engines is nothing new but news to me is that the 115 TSI petrol engine is fitted with an Otto Particulate Filter (OPF) to trap soot particles in the exhaust system. If you regularly do high speed, long journeys there's no problem as the soot trapped by the filter will burn off naturally. Unfortunately, pootling around as I do at 40-ish mph in higher gears just adds to the soot build-up. The garage found my OPF was partially blocked which they cleared with a forced OPF regeneration process. Hey presto - the idle speed dropped from 1400rpm to 900rpm when warm. It seems the engine management was keeping idle revs high to compensate for the partially blocked filter.
The car now feels so much better to drive. So take note if you are a careful, low mileage driver. I was advised to hold the engine revs over 3000rpm occasionally to help clear the OPF. Hope this may be useful to others.
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277 Posts
Found this brief article about OPF Regeneration:
There are many similarities between a diesel DPF and a petrol OPF, one being that the filter will eventually become clogged with particulate matter (soot). Therefore, in order for a petrol filter to burn off the soot, deceleration must occur. To elaborate, deceleration can be done by carrying out ‘engine braking’, which is when you release the accelerator pedal (e.g. downhill descents).
This then ceases the fuel injection and increases the airflow going through the engine and the exhaust system. Consequently, the temperature of the petrol filter will increase enough to ignite the trapped particulate matter.
However, in situations when deceleration is infrequent, the system that controls your engine will delay the spark timing, which will create a light air-fuel ratio, or in other terms, your engine will begin to run ‘lean’. This, in turn, will allow more oxygen to be available which will help regeneration to be initiated.
All this is certainly something that the handbook doesn't even mention. No wonder the engine performance can vary day-to-day.
There are many similarities between a diesel DPF and a petrol OPF, one being that the filter will eventually become clogged with particulate matter (soot). Therefore, in order for a petrol filter to burn off the soot, deceleration must occur. To elaborate, deceleration can be done by carrying out ‘engine braking’, which is when you release the accelerator pedal (e.g. downhill descents).
This then ceases the fuel injection and increases the airflow going through the engine and the exhaust system. Consequently, the temperature of the petrol filter will increase enough to ignite the trapped particulate matter.
However, in situations when deceleration is infrequent, the system that controls your engine will delay the spark timing, which will create a light air-fuel ratio, or in other terms, your engine will begin to run ‘lean’. This, in turn, will allow more oxygen to be available which will help regeneration to be initiated.
All this is certainly something that the handbook doesn't even mention. No wonder the engine performance can vary day-to-day.
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