Tune Resistor - ECU Mate "Limp No CATS"

[MPoxon]

Evening all,

The Griff seems a bit less responsive than it used to be and I am now hitting the rev limiter at about 5.5k instead of 6.25k. I plugged my Steve Heath ECU mate in and the map selection is showing as "Limp No CATS". According to the manual this means that no Tune resistor has been detected and the map selected is the Limp Map.



My car has a Tornado ECU fitted. I have spoken with Mark Adams and he says that the ECU must either be fitted with a white tune resistor (CAT) or a green tune resistor (NON CAT)

At the local PH meet I plugged the reader into two other TVRs with 14CUX and they both also read "Limp NO CATS". One had a TVR Power EPROM, the other standard.

Does anyone else have a 14CUX with a tune resistor fitted and an ECU mate? What does yours show?

Thanks in advance

Matthew

[MPoxon]

This is what the tune resistor looks like Eddie:



There is a small blue connector in the loom near where the relays are where this connects in.

I will try all the suggestions above later today and report back.

[MPoxon]

Afternoon gents, thank you all very much for your replies.

I powered the car on today and the ECU Mate still reads "Limp No CATS"

It looks like the ECU is not detecting any resistance and putting the ECU into the default limp map.

After a 10 minutes of fiddling with the loom and re-making the connections on the tune resistor - powered on and now get the correct reading "White + CATS"


Steve good to see you still lurking around the TVR forums, thanks for your help I know you must be very busy with the Phd.

Eddie if you are after useful information then have a ganders through this - very useful indeed:
http://www.actproducts.co.uk/category/lucas-inject...

My next question is if you have a car with o2 sensors but it does not have any cats should you run a white tune resistor or a green one? My understanding is that the white tune uses o2 sensors where as the green tune ignores them.

[MPoxon]

blitzracing said:

If the resistor is open circuit or disconnected it defaults to map 5, it wont force it into the limp home map, so you still have (or had) another issue. Did you check the error codes? The green map ignores the lambda probes, but unless you have a specific map for your engine (not the default TVR chip) its not recommended. You need the white one for the catalysts.

Hi Mark,

I have checked the ECU for any fault codes and none are present. All of the readings shown by ECU Mate seem to be (from my very limited experience) OK.

The tune resistor is an interesting one as e according to a number of sources Map 5 (open circuit) is described as a limited limp map. But this is different to Limp mode which can occur on any map if the ECU detects an issue.

Colour	Value	Catalyst	Application
Red	180Ω	No	Australian 3.9
Green	470Ω	No	Europe & UK 3.9 (or 3.5 Disco)
Yellow	910Ω	No	Gulf States 3.9, or Europe & UK 4.2
Blue	1.8kΩ	Yes	Gulf States 3.9, or Europe & UK 4.2
White	3.9kΩ	Yes	Europe & UK 3.9 (or 3.5 Disco)
N/A	Open Circuit	Yes	Limp home map

I don't know enough about the subject but it would appear that where mine was running on map 5 it was not mapped fully as I was hitting the rev limiter early and the car did not feel overly responsive. The ECU mate was not showing any error codes and I believe in the throttle screen it will show "LIMP HOME DETECTED" on the screen if the ECU has detected an error.

I think I will leave mine with the White Tune resistor in for the time being until such a time as I can get the car to Mark Adams to work his magic on the car.

Matthew

[MPoxon]

blitzracing said:

It removes the lambda cycling completely and no longer tries to keep the mixture at lambda 1, so you can run richer at low speed that reduces the shunting, and leaner at cruise that gives a better MPG. The peak power does not change. Only if you have the correct non cat map however-

I might give the green one a go in that case. Mine does not have any cats and has a Tornado EPROM which is mapped on both white and green maps.



That is interesting about your Russian customer, I wonder what EPROM he has if the tune resistor is not making any difference to the map. I assume he has tried measuring the resistance between pins 5 and 27 on the ECU plug to make sure the resisor and loom connections are reaching the ECU OK?