OmniCognateNeutronRangler
Senior Member
All those that have been following the trials and tribulations of my Mercedes ownership will know that I recently had all my O2 sensors replaced on Tesco's ticket. Prior to this the car was running fine. Immediately after having the work done (i.e. on the way home) I noticed a couple of problem and these have remained.
The Problems:
1. Tries to stall when pulling up at a traffic light etc. It has done this about 5 or 6 times since I had the work done. It drops down to about 300 rpm and jumps around like a bucking bronco for about 5 seconds then shoots up to about 1200 rpm before sinking back to it's more normal 600 rpm. On one occasion I took my foot off the brake when it was at 300 rpm and the car shot forward leading me to the susicion that it was sitting in the wrong gear.
2. When I pull up in traffic of at a junction and try to pull away nothing happens and then it happens all at once e.g. I was sitting at a junction to pull out onto a dual carriage way so wanted to give it a bit of welly. Pushed the pedal half way to the floor and.....nothing....nada.....zip.....bubcus, just crawled forward as if I had taken my foot of the brake but hadn't touched the loud pedal at all. Pushed the pedal all the way to the floor (as the cars on the dual carriage way were getting worryingly close) and, to quote top gear, it shot off like a scolded cock.
3. On a couple of occasions it felt like it was accellerating AFTER I took my foot off the loud pedal.
On nthe whole the car just "feels" underpowered at the moment. Even when it is revving towards the red-line it just feels sluggish. Incidentally, it also sounds slightly "rough" between 3000 rpm and the red line.
I took the car back to TP today who hooked it up to it's life support system and came back with a clean bill of health. They also took it for a drive and found nothing. To be fair to them the problems are intermittent so it is very difficult to show them, although anoyingly when I drove away it tried to stall at the lights again (btw, this time I had the aircon on and when it tried to stall the aircon slowed down too - I guess this is because of the load on the engine). Again, in fairness to TP they have booked the car in for a couple of days in May, the first time they had a loaner available, and said they will give it a more thorough going over.
They suggested I kept an eye open to see if it was smoking (any idea why?) and said maybe it could be the injectors. Can anyone think of anything TP could have broken when changing the O2 sensors and if this suggestion of the injectors holds any water? If it is the injectors I am concerned they will say it was cuased by the fuel contamination and not do the work on Service Plus. However it WAS working fine before they did the O2 Sensors. I suppose it MAY just be a coincidence but it seems unlikely.
Malcolm, I know you have already said this is likely to be a mixture problem but does that not all get adjuested automatically by the 'lektronics under the hood? Is it worth getting when of those mobile tuning companies to take a look or do they ot do that on modern cars chocked full of management systems and the like?
The Problems:
1. Tries to stall when pulling up at a traffic light etc. It has done this about 5 or 6 times since I had the work done. It drops down to about 300 rpm and jumps around like a bucking bronco for about 5 seconds then shoots up to about 1200 rpm before sinking back to it's more normal 600 rpm. On one occasion I took my foot off the brake when it was at 300 rpm and the car shot forward leading me to the susicion that it was sitting in the wrong gear.
2. When I pull up in traffic of at a junction and try to pull away nothing happens and then it happens all at once e.g. I was sitting at a junction to pull out onto a dual carriage way so wanted to give it a bit of welly. Pushed the pedal half way to the floor and.....nothing....nada.....zip.....bubcus, just crawled forward as if I had taken my foot of the brake but hadn't touched the loud pedal at all. Pushed the pedal all the way to the floor (as the cars on the dual carriage way were getting worryingly close) and, to quote top gear, it shot off like a scolded cock.
3. On a couple of occasions it felt like it was accellerating AFTER I took my foot off the loud pedal.
On nthe whole the car just "feels" underpowered at the moment. Even when it is revving towards the red-line it just feels sluggish. Incidentally, it also sounds slightly "rough" between 3000 rpm and the red line.
I took the car back to TP today who hooked it up to it's life support system and came back with a clean bill of health. They also took it for a drive and found nothing. To be fair to them the problems are intermittent so it is very difficult to show them, although anoyingly when I drove away it tried to stall at the lights again (btw, this time I had the aircon on and when it tried to stall the aircon slowed down too - I guess this is because of the load on the engine). Again, in fairness to TP they have booked the car in for a couple of days in May, the first time they had a loaner available, and said they will give it a more thorough going over.
They suggested I kept an eye open to see if it was smoking (any idea why?) and said maybe it could be the injectors. Can anyone think of anything TP could have broken when changing the O2 sensors and if this suggestion of the injectors holds any water? If it is the injectors I am concerned they will say it was cuased by the fuel contamination and not do the work on Service Plus. However it WAS working fine before they did the O2 Sensors. I suppose it MAY just be a coincidence but it seems unlikely.
Malcolm, I know you have already said this is likely to be a mixture problem but does that not all get adjuested automatically by the 'lektronics under the hood? Is it worth getting when of those mobile tuning companies to take a look or do they ot do that on modern cars chocked full of management systems and the like?
