BigDusty
Active Member
This forum is not a cry for help (makes a change) but rather to inform and hopefully help others with similar problems.
Over the last few months my car has not been driving as well as it should, not a major problem but it did get a little irritating.
When casually pulling away or casually increasing speed it felt as if the car was holding back, then all of a sudden it would come to life and speed up, it seemed it was caused either by a lack of fuel or due to bad timing. The problem was very intermittent and some days it was worse than others. If you put your foot flat to the floor it seemed ok but I’m not always in the mood for aggressive driving.
Motorway driving was always a bit weird, let’s say I was doing 50mph and wanted to increase to 70mph but gradually, putting my foot on the accelerator a little the car would start to increase speed but you could feel it slightly holding back then all of a sudden it would subtly surge forward, then hold back again, then surge etc and it would keep doing this until I got to 70mph.
As I said it wasn’t desperate but just irritating.
I went through the usual checks and basic maintenance, new spark plugs, HT leads, coil packs, air and fuel filter, Air Mass Sensor, regular oil changes and cleaned O2 sensor. I used fuel injector cleaner and made a note of different brands of petrol and checked the fuel pump, still no difference.
Then I read this article on Oxygen Sensors (came across it on another forum on this site)
http://www.aa1car.com/library/o2sensor.htm
Reading that these O2 sensors have a lifetime of about 100K miles made me have a look into mine. I rang Merc and they were able to inform me that my car still had the original Sensor (Full service history up to and until I bought it). Also, my car has done over 200K miles.
On that note I replaced it immediately and thankfully has cured the problem, the car runs like a dream again.
So my conclusion is that my O2 sensor was still working but had become lazy and was delaying the signal to the ECU to increase (or decrease) the mixture of fuel and air. It all makes sense now.
Cheers
BigD
Over the last few months my car has not been driving as well as it should, not a major problem but it did get a little irritating.
When casually pulling away or casually increasing speed it felt as if the car was holding back, then all of a sudden it would come to life and speed up, it seemed it was caused either by a lack of fuel or due to bad timing. The problem was very intermittent and some days it was worse than others. If you put your foot flat to the floor it seemed ok but I’m not always in the mood for aggressive driving.
Motorway driving was always a bit weird, let’s say I was doing 50mph and wanted to increase to 70mph but gradually, putting my foot on the accelerator a little the car would start to increase speed but you could feel it slightly holding back then all of a sudden it would subtly surge forward, then hold back again, then surge etc and it would keep doing this until I got to 70mph.
As I said it wasn’t desperate but just irritating.
I went through the usual checks and basic maintenance, new spark plugs, HT leads, coil packs, air and fuel filter, Air Mass Sensor, regular oil changes and cleaned O2 sensor. I used fuel injector cleaner and made a note of different brands of petrol and checked the fuel pump, still no difference.
Then I read this article on Oxygen Sensors (came across it on another forum on this site)
http://www.aa1car.com/library/o2sensor.htm
Reading that these O2 sensors have a lifetime of about 100K miles made me have a look into mine. I rang Merc and they were able to inform me that my car still had the original Sensor (Full service history up to and until I bought it). Also, my car has done over 200K miles.
On that note I replaced it immediately and thankfully has cured the problem, the car runs like a dream again.
So my conclusion is that my O2 sensor was still working but had become lazy and was delaying the signal to the ECU to increase (or decrease) the mixture of fuel and air. It all makes sense now.
Cheers
BigD
