Engine Management FAQ

Motec M84 VS M130

We at Rasant products are strong advocates for Motec products. They've proven to be the most reliable and consistent engine management products our team has tested. The goal with our engine management systems is providing an OEM level experience that matches your expectations of a modern vehicle. We feel Motec is the best product to achieve that.

M84 is Motec's "gold box". It's been in production for decades and proves to be a reliable and well performing ECU. While it lacks some of the more sophisticated control items of the M130 it offers integrated dual lambda control, which allows you to monitor both banks of your air cooled engine. This is especially important when running ITB's. It's a huge advantage to see fueling imbalances from bank to bank.

The M84 uses an older communications platform and requires a UTC CAN to USB adapter to go from the ECU to a laptop. Many tuners have this adapter already, and we sell it separately from the engine management system. 

  • Integrated dual lambda functionality
  • Requires UTC port to connect from laptop to ECU
  • Does not support knock detection

M130 is Motec's latest and greatest ECU. It packs improved processing capability, more advanced features, and allows for knock detection. Having knock detection allows the ECU to detect detonation and adjust ignition timing accordingly, potentially saving your engine from a catastrophic failure.

The M130 requires a lambda to CAN (LTC) module to view fuel values, our default M130 system offers a single channel module, while the dual lambda monitoring is offered as an upgrade option.

Our M130 engine management systems include our in-house developed TPS based firmware package that makes tuning individual throttle bodies much easier. We can also provide GPA or similar firmware packages non-ITB applications.

  • Uses external lambda to CAN modules
  • Connects to laptop directly with ethernet cable
  • Integrated knock detection

Wiring Comparison

All wiring work is done in house at Rasant Products. Our wire harness are designed similiary to the 964 Motronic units. The ECU is under the drivers seat with the harness passing through the fire wall near the driver side shock tower. There's a fuse and relay panel conveniently located in place of the factory CDI box or ignition coils.

We offer two harness variations: Standard and Mil-Spec. Our standard wire harness uses a high grade automotive wire (TXL) along with a fiberglass loom. Connectors and loom are sealed with an adhesive lined heat shrink. The harness is passed through the chassis using a rubber grommet with a metal plate adapter.

The mil-spec harness uses all new material for both the wire and loom. The wire is mil-spec tinned copper Tefzel wire that has improved abrasion and temperature capability. The added rigidity of this wire allows us to concentric twist all branches of the harness. This provides added flexibility and minimal strain on individual wires. Each connector has a Raychem boot with epoxy to seal the connector end with the harness, ensuring a complete seal. The harness also includes a cylindrical bulkhead connector which allows for easy install/removal of the engine.

Standard Harnesses:

  • Fiberglass loom and TXL automotive wire
  • Connectors sealed with adhesive lined heat shrink
  • Harness is passed through chassis for install/removal

standard harness 1

standard 2

Mil Spec Harness:

  • Raychem DR-25 loom with mil-spec Tefzel wiring
  • Connectors sealed with specialty raychem boot and epoxy
  • Includes bulkhead connectors for firewall

rasant mil-spec


Ignition Comparison

Rasant offers Bosch and WeaponX coil on plug ignition coils. Many of our customers are running Bosch coils. We like that they have integrated coil drivers which helps simplify the wire harness and packaging in the engine compartment. For 964+ owners that have factory power steering the WeaponX coils are a must to clearance the pump on cylinder 6.



  • Simplified wiring and packaging in the engine compartment
  • Known Bosch brand
  • Does not fit with factory power steering


  • Requires external coil drivers mounted in the engine compartment 
  • Claim improved spark energy over factory options
  • Provides clearance for factory power steering

Cam/Crank Systems

Rasant offers two options for cam and crank pickups:

Pulley Side:

  • Default for 2.4L-3.5L applications
  • Early engines that don't have a 60-2 flywheel
  • Rasant includes our cam/crank housing that goes in the distributor hole
  • Includes cam sensor, crank sensor, crank pulley and trigger wheel
  • Allows for sequential ignition with minimal install effort

Flywheel Side:

  • Default for 3.6L+ applications
  • Later engines using a 60-2 flywheel (964/3.6L+)
  • Machined adapter to aim Motec sensor at the flywheel
  • Requires drilling and tapping the rear of the camshaft
  • Includes cam sensor, crank sensor, and machined adapters

How It's Done

Installation instructions