Engine cuts power sometimes when accelerating through corners?

[Intuit]

@HmongFiesta - Re fuel, is it more or less prone based upon full or empty tank?

 

[HmongFiesta]

Initially thought it mattered if it was full or not too until this happened on a fresh full tank of 93.

 

[dhminer]

I'm back from more testing

ECS Disabled (press and hold for 5-10s) makes a BIG difference. Normal or Sport, it feels like the power disappears abruptly and then slams back in abruptly. ECS Disabled, the sense of "loss" is far, FAR less dramatic. It may only be the sensation of the TVC (brake vectoring) kicking in AFTER wheelslip has already occurred. Or that is how it felt to me 10 mins ago, running the same few corners back-to-back, trying to match speed, in the different modes.

Ford did a great thing, IMO. I HATE the Traction Control (Normal or Sport) but LOVE Torque Vectoring (TVC, all modes). Now if I could just set it to ECS Disabled on startup by default my "life would be perfect".

Someone on here made a little harness to trick the car and start up with traction control off. Can’t remember who but it’s out there.

 

[Intuit]

Someone on here made a little harness to trick the car and start up with traction control off. Can’t remember who but it’s out there.

https://www.fiestastforum.com/threads/plug-and-play-traction-control-off-module.18531/

 

[Intuit]

I'd imagine that the stability/yaw control system (TCV) was calibrated to the OEM suspension and braking system. Improved braking may have an unintended side-effect. I've noticed an uncharacteristic sluggishness exiting (but still on) corners and figured i was yaw-control braking. I thought it was just the additional tire weight but the additional body-roll on slightly larger but much softer sidewall could be making yaw-control braking more aggressive too.

Be nice to have a dash light to see when all these e-nannies are activating. Maybe one of you handy techs will be able to put that up on our infotainment screen. 😉

Thinking outside the box a little...

"Brake Over Accelerator" notice Ford 2016 Service Manual...

"Note: On some vehicles, for off road use the brake over accelerator feature can be disabled along with the electronic stability control system by pressing and holding the traction control OFF button for 5 seconds.

The brake over accelerator feature may not be active during low speed operations. This enables unique drive maneuvers, such as trailer tow, boat launch and retrieval, or operation in hilly environments, where the operator may require the application of both the accelerator pedal and the brake pedal during low speed maneuvering. The brake over accelerator feature will be active at speeds greater than 16 km/h (10 MPH).

In the event the accelerator pedal becomes entrapped, such as by an object loding the pedal, the brake over accelerator feature will reduce engine power when the brake pedal is applied.

Operators that rest a foot on the brake pedal when also applying the accelerator pedal may activate the brake over accelerator feature. The brake activation is detected by the PCM from the electrical brake switch. In addition to brake over accelerator comments, the customer may bring the vehicle in for repair to address concerns such as a hesitation/stumble or a lack/loss of power. In the event of a hesitation/stumble or a lack/loss of power concern, carry out normal vehicle diagnostics for the appropriate symptom code. If the brake over accelerator feature is suspect, the BRKOVR_ACTION, BRKOVRD_POSS and DIST_BRKOVRD PIDs will display a brake over accelerator event occurred.

In the event the brake over accelerator is suspected as the cause of the customer concern, explain to the customer the details of the override system as described above. Additionally, make sure the customer is aware that resting a foot on the brake pedal whiel driving may cause the activation of this feature. This also results in activation of the brake lights on the vehicle while held driving. For additional information, refer to the Owners Literature."

 

[HmongFiesta]

So update, turned off ESC completly, made a moderate right hand turn on a decline annnnnd 0.60 OAR immediately from -1.00 OAR.

How would a fuel pick up tube be moved to create this? Is there anything else you guy can think of that would cause this huge OAR effect? Thanks.

 

[Intuit]

Does simulating the same engine load on lighter acceleration and cruise result with the same increase in Octane Adjust Ratio value? It's possible that the turn itself has nothing to do with the change; it is merely the engine load and acceleration that occurs moving on a decline. Does adding Lucas Octane Booster have any impact?

 

[HmongFiesta]

I have never experienced a change in the OAR value instantly and to this degree (it's always goes to 0.60) with bad fuel, only with the circumstances I described.
Any acceleration or decleration has no effects of any kind, I see negative correction with bad fuel and that's about it.

I haven't tried any octane booster but I guess it doesn't hurt to try but I don't believe it is fuel quality. I can drive with -1.00 OAR forever if it don't make any moderate to hard turns.

 

[Intuit]

Only thing that comes to mind is fuel floats on water. Maybe there's a bubble of water wondering around the bottom of the tank? Kind of reaching, I think, but is the only thing I got at moment. Got me stumped. It's weird. 🤷‍♂️

 

[HmongFiesta]

Me too. Appreciate it. Gonna hit up the dealership and some ASE peeps I know, hopefully something comes out of it.

 

[HmongFiesta]

FYI fellow Fiesta ST owners, still have this problem but it appears to be low oil level, it has only happened once since I poured about half a quart or so of oil in. Turned off my CEL and I had to go relatively quick through two consecutive roundabouts.
Going to do a compression test. Have some CELs, camshaft sensor saying both intake and exhaust out of spec.

 

[Sam4]

Its not slowing the car - just controls (limits) boost in a very obvious, abrupt way. I have an on ramp that is a perfect 2nd gear in boost slide....NOPE!! Yaw control every time!!