switch instead of resistor on ecu

[chrisdurham]

hi guys,

had some free time tonight to start having a proper look over my new chim - and i think the most amount of effort is going to be wiring related.

see picture below - i see the single resistor has been changed for a switch.

when its over where the white mark is, resistance between the pins is 3.91K ohms.
when its over at the opposite side, resistance between the pins is 0.469K ohms.

so should i just remove this switch all together? and put the stock resistor back in (once i have sourced one)

and in the mean time - which way should i have it set?

having a few running probs, but want to get it back to std first....

[SILICONEKID340HP]

Go from a catalyst to non catalyst map..! Blitz will explain

[Cider Andy]

The ECU has the capacity to store five different maps on the one EPROM. The resistor to which you refer (the tune resistor) selects which map you use. TVR only used two maps, one for cars fitted with catalytic converters, the other for cars without. In your photo I can see what appears to be two resistors wired in series with a switch to short one out. If you connect a 470R resistor, the ECU will select the non-cat map; a 3K9 resistor will select the cat map. With the resistor disconnected the ECU will default to the cat map. It's clear your car has been modified to enable you to select one of two maps at the flick of a switch.

As far as which resistance to select is concerned, it depends on what's on your EPROM. If it's been 'chipped' there's no saying what's on the EPROM: the resistor simply tells the ECU where to look for a map on the EPROM

[chrisdurham]

hi there, thanks for explaining that - ive taken a pic of the chip that the previous owner has fitted. the car is a 4.3 and I dont think there are any other hardware mods from whatt i can tell.

[chrisdurham]

[SILICONEKID340HP]

Torque V8 ! that was a popular upgrade a few years back ,i bet your AFM looks like this .

http://www.pistonheads.com/gassing/topic.asp?h=0&a...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...





http://www.torquev8.com/


Its called a Torque flow upgrade ,Tell you the truth its a bit of a bodge . [url][img]

Edited by SILICONEKID340HP on Tuesday 22 May 22:52

[Pupp]

SILICONEKID340HP said:

Tell you the truth its a bit of a bodge

Like 'cos the rest of a TVR is engineered in the manner of a Swiss watch

Chances are the plenum will have an oversize throttle plate (72mm ish) - quite sought after by those wanting big numbers

[chrisdurham]

hi,

no its a stock afm and pipework

[SILICONEKID340HP]

That chip is a standard chip with torque flow on it(usually a 5l chip) ..Looks like someone as got rid of the AFM and left the chip in.

[chrisdurham]

i got a bit of a waffle when i bought it - saying it was running lean - so tried out lots of chips, and this one sorted it? and the resistor switch was to get it through mot emmisions time. lol

[chrisdurham]

ok, bit of an update for today,

switched back to the original chip (that i was given with the car) and put the switch to the "cat" map.

it wasnt very happy, very hesitant when coming on throttle.

switched it to the "non cat" map went for another run and the hesitance was gone.

overall i dont think it goes as well on this std chip?

maybe the chip was changed and the diff resistor used to mask an underlaying fault?