Hi all,
my rustbucket has my (very reliable) local indie scratching his head. He's not without possible answers, but the symptoms are unusual, in his experience.
The main symptom is a 95% drop in power under hard acceleration, usually after a kickdown or when cruising at motorway speeds. Basically the engine shoots up to around 3000 rpm and then sticks with a resulting drop in power, as if the turbo not working, with a bit of smoke out the back too. It does not go into limp mode and within a second or two of lifting off things go back to normal.
Other than this the car is driving quite well with 175k on the clock. It had two injectors replaced last year which cured some vibration. It did have the alternator changed about 6 weeks ago. This was by a different (non-merc specialist) indie unfortunately because we were away from home and the car needed recovered after failing catastrophically on the road
Other than that it has had a less-than-ideal couple of years mainly with gearbox problems : rpm sensors, tranny fluid in the EGS thru' the wiring loom
, but also with two new front shocks and drop-links.
I am normally pretty easy with my right foot and car tends to be driven below 2000-2500 rpm.
After having a drive my man's initial guess was that the turbo was being starved of air, and that the MAF or "valves" controlling the airflow may be at fault.
So he had it in today. He was leaning toward the cat being blocked for a while, which he ruled out by disconnecting it with no improvement. He also swapped out the MAF with no joy either. Now the suspicious finger is pointing at some sensors (transducer?)
What has him head-scratching is that when the engine gets to high revs, and turbo spools up, the air intake pipe at the front of the car suddenly becomes squashed as if the engine can't get enough air and the suction cause a vacuum that compresses the intake pipe. I assume this then causes the drop in power as the engine is then starved of air.
What it seems to suggest is that the turbo is actually 'over-boosting' and he thinks that the turbo is not dumping as it should. He is happy that the turbo itself is functioning, he isolated it and it runs as it should.
The STAR software is not being too helpful, all it reports is something like "Implausible boost" and "Implausible transducer" (I didn't see it myself)
My guy's plan is to get it back in when he has another E320 in the shop and start swapping some of the sensors to see if can track it down without starting to just replace the sensors one by one at my expense.
So, any thoughts or suggestions would be welcome that might save us some effort.
thanks
my rustbucket has my (very reliable) local indie scratching his head. He's not without possible answers, but the symptoms are unusual, in his experience.
The main symptom is a 95% drop in power under hard acceleration, usually after a kickdown or when cruising at motorway speeds. Basically the engine shoots up to around 3000 rpm and then sticks with a resulting drop in power, as if the turbo not working, with a bit of smoke out the back too. It does not go into limp mode and within a second or two of lifting off things go back to normal.
Other than this the car is driving quite well with 175k on the clock. It had two injectors replaced last year which cured some vibration. It did have the alternator changed about 6 weeks ago. This was by a different (non-merc specialist) indie unfortunately because we were away from home and the car needed recovered after failing catastrophically on the road
Other than that it has had a less-than-ideal couple of years mainly with gearbox problems : rpm sensors, tranny fluid in the EGS thru' the wiring loom
, but also with two new front shocks and drop-links.I am normally pretty easy with my right foot and car tends to be driven below 2000-2500 rpm.
After having a drive my man's initial guess was that the turbo was being starved of air, and that the MAF or "valves" controlling the airflow may be at fault.
So he had it in today. He was leaning toward the cat being blocked for a while, which he ruled out by disconnecting it with no improvement. He also swapped out the MAF with no joy either. Now the suspicious finger is pointing at some sensors (transducer?)
What has him head-scratching is that when the engine gets to high revs, and turbo spools up, the air intake pipe at the front of the car suddenly becomes squashed as if the engine can't get enough air and the suction cause a vacuum that compresses the intake pipe. I assume this then causes the drop in power as the engine is then starved of air.
What it seems to suggest is that the turbo is actually 'over-boosting' and he thinks that the turbo is not dumping as it should. He is happy that the turbo itself is functioning, he isolated it and it runs as it should.
The STAR software is not being too helpful, all it reports is something like "Implausible boost" and "Implausible transducer" (I didn't see it myself)
My guy's plan is to get it back in when he has another E320 in the shop and start swapping some of the sensors to see if can track it down without starting to just replace the sensors one by one at my expense.
So, any thoughts or suggestions would be welcome that might save us some effort.
thanks
