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DBW Random Throttle Fault

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I have been having very random throttle faults on one bank of my R35. Car will go months without throwing a fault and then at the worst time throw a fault. Yesterday I had to pull over on the side of busy freeway with a narrow shoulder to cycle the car.

I have rebuilt the throttle body with new internals and it made the faults less frequent. The tracking seems fine from 0-100% when stationary and the faults seem to happen when at part throttle or coming off the throttle.

Going to redo the manual calibration steps but wondering if anyone else has any ideas on things to try as everytime I think it’s fixed the car drives fine for weeks and months and then all of a sudden it comes back.

Usually you can reset an Aim Tracking Fault, by just letting letting the throttle pedal return to 0 for about 1 second, then pressing it again, and it should recover.

To understand what's happening you need to log "Throttle Servo Bank x Position Sensor" Main and Tracking. These need to stay very close (use "Throttle Servo Bank x Position Sensor Tracking Linearisation" if these needs to be corrected for any part-throttle differences. A trick to setting that up is to temporarily make "Throttle Area" table linear, and either move the throttle with the pedal, or disconnect the motor and move it manually, watching the Main & Tracking % to see how close they match. I think it should be within 1%.

Good Luck!

Hi Miguel,

Do you have the logging from it occurring?

BlackRex- It’s has been very hit and miss and usually happens under the logging thresholds- will adjust and see if I can get a log.

David - I will take a look and thanks for the suggestions.

One odd thing which is making me think there may be a mechanical issue such as a slightly bent blade or something is that with the engine off and WOT I see big fluctuations in the servo duty cycle - in different conditions sometimes it’s 30% and sometimes 70-80%

Dave - I changed the power save from 2s to 1s, I couldn’t find a channel to monitor when it enters and exits power save. Do you know which one I should monitor

Throttle Servo Bank x Diagnostic is the channel that will cycle between OK (servo is being controlled) to Aim Tracking Fault then Power Save when it's shut down. You need to be logging this fairly quickly as Aim Tracking Fault is only true for a short period before it becomes Power Save.

Whenever you find it in Power Save, you need to let the Throttle Pedal return to 0% before it will attempt to become active again.

The Power Save delay only applies when the engine is not running, and the pedal is 0%, so I don't believe changing that will make any difference in the behavior you are experiencing.

Thanks - here is a log - will try to get a better one shortly. I dont see it ever go into power save and hence when I get a fault I end up having to pull the car over and cycle the ignition which is not ideal.

I have a new Throttle body on the way as its clear bank 2 is having issues between tracking and main

Attached Files

Hi Miguel,

Your particular package doesn't have a power save state, and as such you won't find a power save delay setting. Due to the torque model of your R35 package, this setting was ommited.

As you can see in the first pic, the throttle servo bank 2 main position sensor takes a while to get to 100%. This is causing the motor to have maximum duty applied to it to try and open it. because the tracking sensor works as expected and the main slowly gets there, I would go out on a limb and say the wiper or track for the bank 2 main position sensor is damaged/sticking, so it isn't tracking correctly.

Unfortunately the point where it registered a tracking fault there is a break in the logging, but it indicates bank 2 at fault. With the above diagnosis, a replacement throttle body should rectify the issue.

Attached Files