No Wide Open Throttle (WOT) fuelling for TR8/USA specification vehicles.

James Tencate editor of the "The Bulletin" USA Triumph magazine found he did not get WOT enrichment when he floored the throttle pedal, so he contacted Albert Tingey, who worked on EFI engines at Lucas, to ask for his help. This is Albert's reply.

Solving this problem proved quite difficult as all possibilities had to be explored. I tested four ECUs and found they gave the same results. I then tested a genuine ECU (explanation later) built for V8s without Lambda. This did give WOT enrichment. My neighbour then scoured the internet and found a past report indicating that some ECUs were built without two components enabling WOT enrichment. These being R901 (turns on WOT enrichment) and D803 diode (switches off Lambda). I fitted both to an ECU and found it works. It also altered the throttle potentiometer algorithm.

Solution
Fit the two missing components. R901 220k resistor and D803 std diode (must be fitted the right way round). The total throttle pedal movement should be 12cm. Reset closed throttle potentiometer to 300mv between Red wire and Yellow wire. (Do not use Red wire and vehicle ground. The Yellow earth wire is protected against spikes which could damage the 5volt supply.) You will get WOT enrichment at 10cm of pedal movement and at the throttle potentiometer 3volts.

Road Assessment.
I found fast throttle movement to WOT in 2nd & 3rd gear had a slightly more solid feel. Up a long steep hill 0.7 miles long, starting at 40mph in 5th gear, finishing speed roughly 65mph, showed a 1.5 second advantage with WOT enrichment over 3 runs.

How to check if your ECU has enrichment.
In the passenger foot well there is a plastic 4 window straight connector. This is for checking lambda outputs, and should be used for setting fuel at idle. Midway is 2.5 volts. Top black wired connector is ground, next down is 12volts, next down is lambda output, next down lambda output. Connect volt meter between ground and a lambda output. With a hot engine the voltage should fluctuate around 2.5 volts. Drive the vehicle, select 5th gear, open the throttle. At WOT the voltage fluctuation should stop , if not, you have no enrichment. I expect no increase in fuel consumption resulting in fitting these components.

Explanation European ECU
The lambda board in the ECU has no lambda circuitry and board sizes in this ECU vary in size. Do not ask me why.!!!!!

How to test for WOT enrichment
The best way is to have a look. Remove the 6 securing screws. Nothing else to do except look for R901 resistor (ed. See diag. above). If it's there then you have it.

There is another way, remove the throttle Potentiometer, reconnect potentiometer. With the engine at idle, lean off on the AFM till you hear the RPM reduce. Rotate the throttle Potentiometer very slowly until WOT is reached. You should hear the engine increase speed. If not, good chance no enrichment available.

Please reset throttle Potentiometer to 300mv.

ECU
It would appear the ECU numbers 83721A & 83617A do not have enrichment. ECU 83511A does have enrichment but no lambda sensing.

On behalf of Lucas and myself I would like to apologise for this error of judgement, I had no knowledge of it. Triumph must have known.

Albert Tingey