Jonty's MR2 Turbo

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Aerial override

The stock stereo electrical setup, i.e. head-unit and wiring, will raise the aerial mast for radio and lower for cassette or CD.  With some aftermarket head-units however this feature is inadvertently removed with the aerial raised whenever the unit is on.  I very rarely listen to the radio in my car so disapprove of the unnecessary wear and tear being exerted on the aerial.  With the addition of a switch and interception of appropriate wiring I can now override the car's aerial control and keep the mast lowered.

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Engine start button

Shouldn't an exciting car to drive be just as exciting to start..?  Many classic sports cars (and some modern ones) have a push-button engine start.  Taken from the Honda S2000, the engine start button is a direct replacement for the cigarette lighter which simply doesn't get used.

Installed parallel with the key barrel, the legacy start option remains and illumination comes from the cigarette lighter feed (so the button lights up when the sidelights are turned on).  The button, module connector, modified trim insert, and fitting instructions were supplied by Bernd Betz who lives in Germany.

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Headlamp retractor control unit

The MR2 controls the headlamps via a retractor control unit.  It incorporates a maintenance feature which can leave the lights up but not illuminated (useful when cleaning the lenses and changing bulbs).  Due to the wiring of the unit, a drawback exists -- using your main-beam when only the sidelights are on will leave the headlamps in the up position.  With a switch, some wire, and some solder a simple yet effective modification can be made to the control unit.

A connection is intercepted which allows the maintenance feature to be turned off.  Whilst off, flashing with sidelights on will result in the headlamps retracting.  Should a bulb need changing or lenses cleaned, the maintenance feature can simply be turned back on again.

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Fuel-cut

Turbocharged cars typically have an over-boost shutdown incorporated into the ECU.  This is a safety feature which prevents the turbo from boosting itself into oblivion, causing permanent damage to itself and the engine.  The MR2's ECU monitors boost pressure and will execute fuel-cut should the pressure breach a pre-defined limit.  Fuel-cut means no combustion and therefore no exhaust.  With no exhaust gases to drive the turbo, it spins down.

Fuel-cut for a Rev1/2 MR2 Turbo is around 12 psi (that's 2 psi above stock boost pressure).  To by-pass this, either a diode or an electronic fuel-cut defender (FCD) must be used.  The diode is a very cheap and crude method which completely removes fuel-cut whereas an electronic 'voltage clamp' allows for the threshold to be raised instead.

Typically, voltage clamp FCDs are adjustable, allowing the user to pre-set when fuel-cut should return.  The obvious benefit here is that the over-boost safety feature can remain and be adjusted as required.

This is my FCD -- the TRL Performance VFCC (Voltage Fuel Cut Controller).  It's tiny enough that it can quietly sit on top of my ECU casing and is set so that fuel-cut will return at 17 psi should anything go wrong.

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Rear fog lamp

If your car's been imported then it won't have a factory-fit rear fog lamp as these simply weren't required for the Japanese market.  Naturally it may have a fog lamp of some kind if an importer or previous owner have engineered one (by adding one, modifying, or changing the rear lenses).

Standard Japanese MkII models have a 4 x stop/tail light configuration and to pass the UK MOT a dedicated fog lamp is required.  Although not applicable to me now (since changing my rear lenses) rather than add an external lamp to the bottom of the car I decided to wire-in some diodes which would allow a stop lamp to double-up as a fog.

A Ford Sierra fog lamp switch is an almost perfect fit and requires minimal trimming so that it locks into place of a blanking panel.  The necessary wiring from the switch to the diodes at the rear of the car allows for one of the rear brake lights to be illuminated.  All lamps still function as usual, i.e. two pairs of stop/tail lights but with the added bonus of a fog lamp at the press of a button.

It's important to note that for a UK MOT the above modification isn't 100% friendly because a rear fog lamp should be dedicated and not dual-function.  Pass or fail may therefore vary between testers.

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Brighter dial bulbs

The bulbs inside the dial unit (which illuminate the speedometer and rev counters) blacken over time and without a rheostat can lead to a dim display.  Rated at 1.2W the standard bulbs can safely be replaced with 3.4W versions which are slightly brighter and cheap to replace.

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