Cornering limp mode

[Phil7500]

So I have a stock 2015 1.0 Zetec S Red Edition with 75K Miles. regularly serviced. Experiencing the following problem - when cornering (typically occurring in third gear, fast cornering/ roundabouts with constant throttle, then when building revs out of a corner/ roundabout), at around 3.5k revs, the engine noticeably looses power, goes into limp mode and the service engine light shows on the dash. I can turn the car off and on again, the service light disappears and the engine regains power as if limp mode has been disabled. So far I have replaced the boost solenoid, vacuum pump and the small valve on the pump, map sensor, and checked that the waste gate linkage isn't in contact with the heat shield. The car is also showing a p0420 error so I have changed the (damaged) flexi-pipe after the cat and added o2 sensor extenders thinking this will fix that problem without replacing the entire cat (Could be unrelated). I have read on these forums that people are experiencing a similar limp mode issue when cornering as a result of a faulty/ blocked fuel pump filter assembly - however, this seems to be occurring on diesels.
Wondering if anyone has experienced this problem on a petrol 1.0L and if so what is the solution to the issue.

 

[Handy Andy]

75K miles? Or km? When either, the issue of a bearing comes into play (sic) as in a failure when you turn corners, a ringed tooth gear can wobble out of position within the bearing hub (or pinion to ring -to- tooth mesh of a senor) and the system loses tone with it. Only not all the tone is lost, only enough of this erroneous signal is enough to tell-tale that the system is thinking you have a major fail in some portion of the drive-train, which in this - sounds like an output versus input speed sensor - the system can't interpret the error so it's thrown into limp mode.

IF enough torque is applied the system - it can see a jump in speed - enough to make it think you have a major slip or turn - loss of control - issue that it cannot resolve until you can restart.

Did you try this with Traction control off? See if this can be repeated so you can have a mechanic or witness with enough wits about them to help you describe this to the shop so they know where to start looking?

 

[Phil7500]

Hi Andy
Interesting theory? This fits with it only happening when going round corners. If turning the traction control off stops it from happening how do we work out which one of the two front wheels is affected, ( I'm assuming there are only wheel speed sensors fitted to the front of the car?)

 

[Handy Andy]

IT can provide the mechanic a means of direction; to localize the condition to a sensor or harness that works those sensors.

It may also mean freeze frame data may need to be collected so the mechanics can see how the "fault" forms as step by step action and from which sensor does this fault cascade from?

You also have EPAS, which is electronic steering motor-driven - so it's possible the condition may exist. But, due to wear and tear and the EPAS - forcing the turning but the worn suspension and steering linkage may result in faults the speed sensors pick up as potential skid and tries to regain control but from what?