Loss of power on a left turn.

[Marty65]

Hi folks, my E86 3.0 Si has started misbehaving on left turns. All power just leaves the engine. No lights on the dash. Thought it may have been to with DSC but does the same when off.
Anyone experienced similar or have any ideas to pinpoint the problem?

[enuff_zed]

Have you done any work on it recently that may have disturbed something?
High speed or low speed?
Full lock or gentle turns?
Any codes stored?

[Marty65]

Only work carried out over the past 10 days was coolant change.
Only done local trips since it started so between 20 - 30 mph on 90 degree cornering.
Zero codes showing but only a cheap OBD. Hoping I can get a proper diag done over the next couple of days.

[enuff_zed]

Only work carried out over the past 10 days was coolant change.
Only done local trips since it started so between 20 - 30 mph on 90 degree cornering.
Zero codes showing but only a cheap OBD. Hoping I can get a proper diag done over the next couple of days.

Very odd.
Either a DSC/traction issue, or inertia making or breaking a contact as you corner.
Just to discount a mechanical issue with something being moved, have you tried putting 90 degree lock on with the car stationary?

[Marty65]

Tried that and no difference in idle speed.

[enuff_zed]

Tried that and no difference in idle speed.

Ok so only in motion.
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

[Marty65]

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...

[enuff_zed]

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...

I’ve said many times I’m strictly engines and airframes but you pick up a bit as you go.
It’s an interesting issue so do let us know the outcome

[Marty65]

I will do

[TOMGREEN413]

Good luck, please let us know how you get on.

[raymond.harper]

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.

[Pondrew]

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!

[enuff_zed]

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!

Exactly my thinking when I was on about it being a mechanical/inertia problem, though I couldn't think what it may be.

[Pondrew]

Exactly my thinking

I feel all warm inside now! Turns out I'm not just a pretty face!

[Marty65]

Yes all possibilities. I hate cars lol