I really like your idea. So your saying if i just apply a brake signal and some amount of throttle the ECU will maintain 1200 regardless of load. I never heard anything like this but I'll definitely be giving it a try as soon as I have time. I wonder if that function could be altered to raise it to 1500 or more?
YES! Exactly.
2000-2200 RPM would be better than 1500 RPM because the engine would be at the sweet spot in the meatiest part of the torque curve and be safe for the engine and turbo.
The ECU tightly governs the engine RPM at 1199 RPM when in high idle mode or brake overrides throttle mode. I don't know what the official name of the mode is.
You can easily test this in a manual transmission ALH TDI. I don't think it works in an automatic ALH TDI. You may need to recode the ECU to configure it for a manual transmission if the ECU came from an automatic car with the dreaded 01M automatic. Older Mk3 TDIs with a manual transmission also have this mode.
Here is the test in a manual transmission ALH TDI: With the car stopped, apply brake using the left half of your right foot. While keeping your right foot on the brake, apply part throttle with the right half of your right foot. The engine RPM will raise up and then drop to a precisely governed 1199 RPM and stay there as long as you keep your foot on the brake and throttle together. Pushing further down on the go-pedal does nothing while in this mode.
With your left foot, you can use the clutch pedal and put the car in gear and try loading the engine briefly by letting the clutch out enough for it to bite in some and then quickly go back down on the clutch. Try this quickly and briefly so you don't cook the clutch. It also represents a step increase and decrease in load like what the engine would see in the log splitter application. You'll notice the ECU will quickly and automatically adjust fueling to maintain 1199 RPM as you load the engine and then remove the load. If you try turning the A/C on and off, you'll notice the ECU adjusting fueling to maintain 1199 RPM with the load from the A/C compressor on the engine. When you try it with the A/C compressor, you'll notice the engine sound will change slightly but the RPMs won't budge.
I liked using this mode for doing aggressive but controlled launches and accelerating away at WOT. It made starting up on steep hills a breeze. By the time the ECU returns full control to the go-pedal, I'm already fully off the clutch and moving and accelerating at WOT.
Hopefully the 1199 RPM set point can be raised to 2000-2200 RPM via tuning. Could this mode really be an "industrial" mode in the ECU?
Good luck.
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