Hi, there is no need to change mapping based on throttle diameter,extreme high boost at the inlet manifold for very low throttle angle will result in P1689......your not going to get that unless you go turbo though, or the bypass valve is wedged shut permanantly! TB related problems that cause idle problems are often down to the machining of the TB bore, the machining and design of the butterfly ,(its diameter and the 'fully closed ' plate angle) , and centralization during assembly. The throttle plate should be at exactly the same angle as stock in fully closed state .With the butterfly held shut and held upto a light, no gaps should be visable around the entire circumference of the butterfly. Basically any gap particularly on an enlarged TB can mean the ECU signal to the TB motor is not able to close the air off enough to achieve required idle speed (in essence the throttle is already fully closed when it should in fact be a 'degree or two' open at desired idle) .The ecu then does weird things trying to reduce the idle, including EML and engine cut . As stated other causes of poor idle and stalling are other air leaks and faulty T map sensors.
Regarding plugs correct heat range for a modded S is B7 (NGK) and IK22 (denso)......most tuners would agree on that. If you need colder plugs then the combustion temps are too high and needs addressing at source
On a seperate note we have another car coming in on a trailor tommorow, apparantly had a conversion elsewhere just done including a remap and yep its gone bang big time.........our advice use stock map + 440cc injectors + GTT adjustable FPR its much safer guys.
Best Regards Roland GTT
