Weird DBW Behaviour & Remapping Simos 9.1 ECU

Hi all,

I am looking to remap my first ECU, using the fundamentals from the courses on here, which im yet to finish. But first, I need to read and write the map.

The car in question is a 2006 VW Fox (1.2L Petrol) using Siemens Simos 9.1 ECU.

As in the image below, for whatever reason, the OEM map closes the DBW throttle body to around 45% under high load. This causes a pressure drop of -0.11bar in the manifold. I can see a lot of power is lost because of the OEM map. Visual throttle body inspection on dyno confirms the OBD readings.

Has anyone experienced such OEM map behaviour on other vehicles?

The other question I have is how I can read and write a map on the Simos 9.1 ECU. So far, for my research, I have found KESS V2 to be the only compatible device with my car. Does anyone know of any other alternatives?

Seeing as KESS V2 is an ODB device, I have read that only partial map dumps can be made in some cases. Could I end up with a partial map dump that does not contain DBW & fuelling info? Would I instead have to resort to something like KTAG?

And lastly, im planning to use WinOLS to modify the stock map. Are there any better alternatives that are free?

Thanks in advance,

Matt

Not familiar with that ECU or car but what you describe/show does sound fairly normal for an EFI control from a modern-ish car. The ECU was likely mapped based on a control strategy called Torque on Demand (TOD) and Force on Demand (FOD). TOD in a simplified explanation is an estimated/calculated actual torque vs requested torque strategy control, based on engine torque characteristics gained on a transient bench dyno.

There are two types of torque requests, slow and fast. A slow request uses the throttle body, a fast request uses ignition timing (typically to pull torque for an automatic transmission shift, knock event, or some other protection strategy). So if the ECU is estimating that the engine has reached the target torque for that operating area, and is exceeding or will be exceeding the target torque, it will adjust the throttle to reduce torque in order to maintain the target. So in your case it's possible that you are seeing the OEM system pulling torque to maintain it's target. If you have modified your engine to breathe better/more efficiently then that may make sense.

To be honest though, that amount of throttle angle reduction does look more excessive than I've personally seen. I would expect more like a 10-20deg reduction from fully open, but I'm not familiar with that engine or ECU. It's also possible you might be getting into some fail-safe, like catalytic converter protection or something. I'd be curious to see what lambda looks like during that pull, as a cat protection strategy would add fuel and remove oxygen (reduce throttle angle) to cool the cat.

i also haven't tuned this system or car but I have heard as above that once you trick the torque limiting these cars haul some great numbers

sorry I can't help much on this I will do some research and see what I can find