Spartan 3 SETSLOWHEAT behaviour

Spartan 3
1

I have read the manual, but it’s not clear how SETSLOWHEAT mode 2 (turn on by RPM or after 10 min) and mode 3 (turn on at 350C or after 10 min) working. Are they functioning like mode 0 (full power heating) or like mode 1 (1/3 power heating) after condition is met?

Also I wonder is it possible to clarify how exactly mode 1 is working? Is it rely on timer or temperature before increasing power? Is increase gradual or instant?

I’m asking cause I’m decided to throw away my AEM LSU 4.9 controller and try Spartan with LSU ADV, but not sure what mode I should use for maximum reliability.

With my current 750 BHP Subaru build lambda sensors are failing like they are disposable, every 1-2 month or so. Sensor installed right after the turbo, but cause of extremely long exhaust manifold and uppipe, and 3.5" exhaust, EGT after turbo is only 150C at idle, below 300C when daily driving and below 600C when all out racing. Moving sensor before turbo is not a good idea for my build cause of twinscroll and need for pressure compensation.
I’m turning on lambda only when engine is running, but judging by how fast sensors are failing this measures are obviosly not enough to protect sensor.

Most likely this happening because of thermal shock caused by 2 reasons:

  1. Sensor is heating much faster than all condensate evaporates from pre sensor exhaust.
  2. High internal temperature gradient between hot ceramic and cold metal when sensor is heating too fast and in cold exhaust.

Currently I’m planning to implement delay by ECU and not turn on Spartan until engine is running and EGT is at least 150С (It can take 5-10 minutes to warm up). This should fully eliminate possible condensation issues and reduce internal sensor temperature diff when heating. Also I’m planning to use SETSLOWHEAT 1 to further minimize possible internal sensor temperature issues.

Is it sounds reasonable or I’m missing something? What is recommended way to use Spartan?

Also though 1/3 power heating is sounds much better then what most other controllers like AEM do (always full power), it’s still more aggressive than heating strategies recommended by BOSCH (start from 1.5V for LSU 4.9 and start from 1.8-2V for LSU ADV). Is it possible to add option for more gradual heating in future firmware updates?

Sorry for so much questions, but I hope this can be really useful for many users.

2

All slowheat modes, 0 to 3, start at 0v.

Slowheat modes 1 to 3, in addition to starting at 0v, the voltage ramps at 1/3 the bosch specified ramp rate.

An unpowered O2 sensor in an active exhaust stream will quickly foul due to carbon buildup as the sensor is not hot enough to burn off excess carbon buildup.

You will need to find a balance between switching the controller on too early to avoid thermal shock, and turning the it on too late and suffer carbon buildup.

I would suggest you start with slowheat1 and not use a switch. If you still encounter issues with the sensor prematurely failing, then use a switch.

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