Front Panel.

AFR Adj Potentiomater

The AFR Adj p-meter (P1) at the front of the DFC can at any time be used to make instantaneous adjustments to the AFR level when operating in the manual (MAN) or in the feedback (FB) mode.

However, before using the P1 there is a base level that must be set for each mode of DFC operation (using T1 for DJ-Base in MAN mode and T2 for AFR-Base in FB mode) as described further below.

Like the initial TS4 IPD Enrichment box the DFCv4 P1 adjustment is intended to allow for on-the-road adjustments – which primarily extends towards a richer fuel mixture than an initially preset AFR level. Such preferred AFR preset level could be close to the stoichiometric 14.7 AFR level for daily driving.

The P1 adjustment range (from the top (0) position – with an already warmed up engine) is more effective turning in the rich direction (up to +40% more fuel) than turning it in the lean direction (down only -5% less fuel). It is therefore recommended when adjusting the T1 DJ-base (with P1 set at the top position) to select the desired max-lean-AFR value you normally want to operate the engine at. However, selecting a P1 position like “10 o’clock” before setting a desired T1 AFR value will increase the P1 lean-adjustment range (down to -15% leaner) and reduce the rich-adjustment range (to +30% richer).  During a cold start when the fuel mixture is often very rich, the P1 will be more effective (than -5%) turning it in the lean direction and hereby reduce an overly rich fuel mixture while the engine is warming up.

AFR Control slide switch:

• OFF position

In the OFF mode, the ECU-10 and MPS-10 signal is interconnected by the DFC, which brings the D-Jet system into the original factory mode of operation. The DFC still receives the ECU-10 and MPS-8 signals, allowing for monitoring of RPM and original MPS/ECU-10 signal level via the DFC Monitor and Logging interface at the back.

• MAN position

The DFC maintains the set DJ-Base signal (MPS-10) without input from the AFR sensor. The DJ-Base trim (T1) at the right side is used to set the desired manual AFR level for a “garage-high-idle” or during driving (2000-3000 RPM) conditions. When operating in MAN mode, the front AFR Adj p-meter (P1) can thereafter be used while driving to make further adjustments.

While (and after) the T1 and P1 settings are made the MPS and ECU will continuedly further modify the T1 set fuel mixture as determined by actual MPS vacuum and the ECU engine speed compensation.

Turning the P1 front control to a leaner position during cold start will help reduce a highly enrichment ECU startup condition and hereby obtain a more neutral AFR condition sooner than otherwise.

• FB Position

After setting the DJ-Base level, the AFR sensor display and input signal is used as input while adjusting the AFR-Base Trim (T2) to obtain a desired AFR level.  While operating in FB mode the DFC is continuously using the AFR sensor O2 input signal adjusting the fuel mixture to maintain the set AFR-Base level.

The AFR-Base level may be set at a different level than the DJ-Base level. This allows for instant switching between two different AFR settings while driving. One example could be to set the DFC-FB mode for economical (AFR 14.7:1 to 15.0:1) cruising conditions, while a richer DJ-Base setting could be desired when operating in the MAN DFC mode.

Before a cold engine start it is recommended to switch the DFC to the MAN mode (or OFF mode) and then switch back to FB mode after a few minutes. However, as some AFR sensor units are presetting the O2 sensor input to a “default neutral feedback signal” during the first minute or so after engine start, it may sometimes be possible to continue operating in the DFC-FB mode also during cold start.

Switching the DFC to the FB mode during warmup will quickly get the AFR level close to the previously set AFR-Base level, allowing you to start driving the car without excessive fuel consumption.

While the DFC is operating in FB mode the O2 sensor input is continuously used by the DFC to control the fuel mixture well into the engine idle (900-1200 RPM) range. This allows for the ECU Idle Control to be disabled – simply by adjusting the TPS position slightly so the TPS Stop Switch will not be closing.

Side Controls:

Right side DJ-Base trim-pot (T1) is used to set the desired DJ-Base level, which is the default base AFR level to be applied during the MAN DFC operation mode.The T1 trim adjustment is providing for the same level of AFR adjustment which otherwise can be obtained only by adjusting the MPS inner tuning screw.

Left Side AFR-Base trim-pot (T2) is used to set the desired AFR-Base level to be applied during the FB DFC operation mode – with or without the use of an AFR sensor.

 Back Side Control and Connections.

Toggle Switch : Adj P1 disable (up) / enable (down

When disabling P1 the DJ-base setting will change to match the top position whenever the P1 is enabled.

Mini-DIN cable – connecting the DFC to the MPS/ECU Adaptor located in the engine compartment including:

> ECU-10 (pin1)

>MPS-10 (pin2)

> MPS-8 (pin3)

> 12-volt DC power input to DFCv4 (pin4)

> GND to DFCv4 (pins 5,5,7)

Socket for 4-pin AMP MINI CT is used for AFR O2 sensor input and alternate 12-volt DC power including:

> alternate 12V under-dash power input to DFCv4 (pin1)

> Alternate GND to DFCv4 (pin2)

> AFR sensor input to DFCv4 (pin4) Rich range: 0V tp 2.2V Lean range: 3V to 5V

Socket for 6-pin AMP MINI CT is used for monitoring and logging of DFCv4 operation signals including:

> Supplied AFR (pin1)

> RPM derived from MPS-8 signal (pin2)

> MPS-10 (D-Jet base) signal sent back to the ECU (pin3)

> 12-volt DC output for connecting optional signal logger module (pin5)

> GND for optional signal logger module (pin6)

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