Limp Home Map - what exactly does it do?

[jazzdude]

Have recently been experiencing some slight hesitance around 4000 rpm so I thought I would connect RG and see what is happening.

The chart showed the car in Map 0, and checking further, it seems one of the wires on the resistor plug has come loose so the resistor was basically reading 0.

I probably have been driving the car around like this for weeks, as the last time I was moving wires around down there was about a couple of months ago. Other than the occasional hesitancy, nothing much else different to the TVR Map 2, which is why I am wondering, what exactly is happening in Map 0?

[blitzracing]

I think it will substitute the failed item with a default setting for whatever sensor, so in this case its dropped to map zero as that input was missing. Like you Ive run map 0 by mistake and you would hardly know. Losing an AFM is a whole different game however.

[jazzdude]

I fixed the resistor blue plug connector and this time wired in the white map 5 resistor to check it on RG.

Running like a peach now, will use map 5 for a couple of weeks to see if any fault codes pop up then will probably go back to map 2. It's much smoother than map 5 but is also about 30% worse on the fuel consumption.

[blitzracing]

You really should not get a drop in MPG with map 2, it should improve as the engine can run leaner under light load without being stuck at 14.7:1 all the time. As you like to experiment, Id fit an AFR gauge and see whats really going on.