Loss of power on a left turn.
- Thread starter Marty65
- Start date
Ok so only in motion.Marty65 said:
I know you think otherwise but most likely thing is the DSC. Or a spurious input from the Steering Angle Sensor. If that doesn’t register a left turn then the DSC will be confused that the wheels are rotating at different speeds. A code reader that can read live data of the steering angle would help. Should be 0 degrees straight ahead and then +/- 540 degrees at full lock
I’ve said many times I’m strictly engines and airframes but you pick up a bit as you go.Marty65 said:I only discarded the DSC because it did the same with it off. I'm not up on electronics. I'm more of a spanner guy so any input from someone who is, is much appreciated.
I'll hopefully be able to get it checked out this week. Thanks for your input and time...
It’s an interesting issue so do let us know the outcome
Good luck, please let us know how you get on.
raymond.harper
Senior member
Do a full scan of the car with a suitable model-specific scanner. Although the problem does not trigger an actual engine code, there may be a fault. If nothing, get a friend to read the special functions/live data on the scanner, voltage, etc, when you turn left using a phone to take pictures of the screen.
The following is not based on any technical knowledge, just trying to think logically;
From the information supplied:
Engine power is lost when turning left whilst moving, but not when steering is turned while stationary.
No obvious faults showing on scanner.
Could it be a fuel supply problem? Either a fuel pump with a dodgy connection, or even something in the tank moving around?
OR even something in the air filter housing, moving around?
Just a thought!
From the information supplied:
Engine power is lost when turning left whilst moving, but not when steering is turned while stationary.
No obvious faults showing on scanner.
Could it be a fuel supply problem? Either a fuel pump with a dodgy connection, or even something in the tank moving around?
OR even something in the air filter housing, moving around?
Just a thought!
Exactly my thinking when I was on about it being a mechanical/inertia problem, though I couldn't think what it may be.Pondrew said:The following is not based on any technical knowledge, just trying to think logically;
From the information supplied:
Engine power is lost when turning left whilst moving, but not when steering is turned while stationary.
No obvious faults showing on scanner.
Could it be a fuel supply problem? Either a fuel pump with a dodgy connection, or even something in the tank moving around?
OR even something in the air filter housing, moving around?
Just a thought!
deltasierra
Member
It could be an intermittent electrical connection if the wiring is able to move in a turn, much more likely is a fuel pickup problem in the tank, either object moving around or a detached pipe.
When you turn the DSC off, are you doing the full-fat 10second press and getting 3 lights up? Otherwise you're only really disabling the traction control.
Start by reseting the tyre pressure monitoring system (and even check the pressures if you like!) as it could be marginal on whinging that a tyre is flat but the rolling radius could be enough to throw the DSC into intervening.
If it's not that it's a tyre issue. I used to get this problem on my 320d at one point when I had notably different tyre makes front to back and also one end was quite new where the other was mostly worn. The DSC is looking at the tyre rotational speeds and, within limits for a given steering input, it knows what ratio of speed differences it can allow. Beyond that it assumes a tyre is slipping. Have a setup where going in a straight line is already giving quite disparate speeds and, on cornering, it looks more like slippage. The effect is exaserbated by staggered setups as they're already likely to be not quite equal circumference front to back. And different makes make different diameter tyres no matter what it says on the side!
Regarding only doing it going left, it could be one tyre is lower tread than its oppo or just the difference in where the weight is located (BMWs are right side heavy in the UK, in LHD-land the battery compensates for the driver a bit) throwing the system.
Start by reseting the tyre pressure monitoring system (and even check the pressures if you like!) as it could be marginal on whinging that a tyre is flat but the rolling radius could be enough to throw the DSC into intervening.
If it's not that it's a tyre issue. I used to get this problem on my 320d at one point when I had notably different tyre makes front to back and also one end was quite new where the other was mostly worn. The DSC is looking at the tyre rotational speeds and, within limits for a given steering input, it knows what ratio of speed differences it can allow. Beyond that it assumes a tyre is slipping. Have a setup where going in a straight line is already giving quite disparate speeds and, on cornering, it looks more like slippage. The effect is exaserbated by staggered setups as they're already likely to be not quite equal circumference front to back. And different makes make different diameter tyres no matter what it says on the side!
Regarding only doing it going left, it could be one tyre is lower tread than its oppo or just the difference in where the weight is located (BMWs are right side heavy in the UK, in LHD-land the battery compensates for the driver a bit) throwing the system.
