Limp Mode / Torque Reduction / Power Loss Left Hand Turns

[Baz_sta]

Hi, I posted online but wanted to bring it to the forums(I know most of you cross over between both but maybe some don't)

Background: I have coded out ice mode/ Brake Fade assist, as per the instructions on here. Installed on the car: Camber plates, Verkline Toe Arms and Caster arms. 275 tire CRS.

If ABS is engaged in a heavy braking zone followed by a hard left hand turn(picture for exact example(The Ridge Motorsport Park) the car falls into a limp mode. It accelerates extremely slowly under wide open throttle. The work around is to upshift and downshift quickly.

Has anyone experienced this?(there is another thread on Here and a video of someone experiencing it) Is this a ride height sensor issue?(they are only on the left side of the car) Does the car even need ride height sensors?

I had experienced this before the brake coding. However it became extremely problematic this weekend visiting another local track with the car.

I don't believe this to be a fuel starvation issue (which I have experienced on right hand turns).

Knowing this issue was happening, I was preemptively doing a up/downshift mid corners on the fastest lap just to avoid the limp mode.

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[kyippee]

I barely use facebook now, so sharing what I shared there.. since your post popped up in a random time I opened FB


I experienced exactly this at Buttonwillow circuit. That 90 degree left turn. It got me very confused. Hard breaking, turn, get on throttle at apex or right after, and very slow acceleration.
No error modes or warnings on screen though. I would upshift and then acceleration would be fixed
--

I do not have a solution. Staying in a higher gear instead of downshifting to be in very high RPM seemed to reduce the chances of it happening though. I think it was staying a gear higher than possible was the fix.

I think my fuel level was good - I am guessing around 60-80% full when it was happening. No surge tank or aftermarket pumps in my car. No special brake coding done and I don't know what that coding is yet. ABS probably did engage while braking into the corner - the tires made the intermittent squeals. No traction control - I turn it fully off.

I was data logging with ecutek during that day, so I do have some data. Here is some analysis done via AI:

Buttonwillow Circut Turn 7 issue was not a gear-selection problem and does not look like fuel starvation or boost leak behavior.
In the bad event, I was exiting T7 in 3rd gear at ~54–59 mph / ~4,900–5,300 rpm with 100% pedal, but the ECU only gave about 30–40% actual throttle and roughly 120–145 Nm clutch torque for about 2–2.5 seconds. Manifold target stayed near atmospheric, so the car was basically not requesting boost.

In a clean T7 pass, the car was also in 3rd gear, similar speed/RPM, but actual throttle opened to ~98% and torque jumped to ~400+ Nm.
Fuel rail pressure looked stable, ethanol content was logged at E10, no obvious knock/misfire/fuel pressure failure showed up, and there was no fuel tank level channel in the log.

 

[razorlab]

The Throttle gets clamped to 20% if the brake signal becomes faulty. I wonder if there is something causing that to happen.

 

[Baz_sta]

The Throttle gets clamped to 20% if the brake signal becomes faulty. I wonder if there is something causing that to happen.

Can you suggest the best data logger(for track use) So that I can log this?

I'm using Circuit Storm/Solo Storm which is pulling the CAN data. I overlayed a log. you can see the demand is for 100% Throttle but the RPM climbing slowly, Speed not climbing and the delta falling fast.(Green is fastest lap)

 

[razorlab]

Can you suggest the best data logger(for track use) So that I can log this?

I'm using Circuit Storm/Solo Storm which is pulling the CAN data. I overlayed a log. you can see the demand is for 100% Throttle but the RPM climbing slowly, Speed not climbing and the delta falling fast.(Green is fastest lap)

Is that pedal or throttle? Pedal would be the request and throttle would be the actual throttle plate. Did you get the CAN info from my spreadsheet?

 

[Baz_sta]

Is that pedal or throttle? Pedal would be the request and throttle would be the actual throttle plate. Did you get the CAN info from my spreadsheet?

I found your spreadsheet and sent it to the developer for confirmation. I believe its likely pedal.

 

[razorlab]

I found your spreadsheet and sent it to the developer for confirmation. I believe its likely pedal.

You can also just add them manually. https://www.petreldata.com/support/...user-guide/#Logger_Channel_CAN_Signal_Mapping

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