yeah i know that.. every VVEL related technical document i've trawled up in my quest to learn more/cure my car has stated not to touch the sensors or actuators unless absolutely neccessary. If one part is disturbed, the entire lot is to be replaced.
I took a calculated gamble and went ahead with the adjustment procedure on bank 1 because at idle and under the adjustment precondition mode, it was out of spec by 0.001v, and also reading +0.05v higher than bank 2. Surely, if the system was indeed that sensitive that any disturbance in its life, whether accidental or intentional would mandate replacement of all parts then the bolts would be of a more tamper deterrent type, possibly even paint marked at assembly. The variances might sound very very tiny but i do believe the VVEL system is very sensitive and that 0.05v might translate into a few degrees or few fractiona of degrees of lift. Either way, if both banks are balanced then in theory the system would run even better - imo at least. I did say a final prayer before i cracked the bolts loose and held my breath. No turning back now.
I actually originally wanted to adjust both banks but when i hooked up Cipher i noticed that bank 2 was very close to spec. (0.499v actual vs 0.500v +/- 0.048v spec). So i let it be. It was quite easy to adjust but i quickly realised just how sensitive these sensors are. It didnt take much rotation to balance it with bank 2.
For anyone who is unsure about the VVEL relay and its location, in my 2011 AUDM RHD Z it is accessible by removing the plastic frame surrounding the battery hatch where there is a small box. The relay is the one as per the label on the lid. For me, that meant the relay nearest to the firewall. Both are identical, Japanese relays which is contrary to the Chinese made relays another member here found in his earlier model Z. Perhaps Nissan realised there was a fault and switched to Japanese relays in later models? I read somewhere that Nissan mislabelled the lid or the fsm but i'm not sure what model years are affected. It might have actually been the G37.. The other relay is for the cooling fans
So, in summary, i replaced no parts and removed no parts. I only backed off the bolts sufficient to allow movement of the sensor for the adjustment procedure. I performed the adjustment in a bid to cure my random loss of throttle response. The car idles perfectly and runs perfectly, with no hint of any ill effects of disturbing the sensors (both sensors were actually disconnected as i was intending on adjusting both). After throwing over $1000 in parts to try and cure the problem, i deemed the risk to be acceptable. I was well aware of what may happen but felr reassured by the several trouble-free reassembly stories other members here have shared when they removed the VVEL to upgrade cams or perform other repairs. These VVEL control shaft position sensors are similar to modern throttle position sensors fitted to cable mechanically operated throttle bodies.
I don't recommend everyone go out there and start fiddling with their VVEL sensors. Not unless you have explored all other avenues, understand the risks and have the proper equipment. It can be done with a multimeter and wire piercing probes but i imagine this would be very fiddly and require an assistant. I used Cipher and a laptop resting on the brake fluid hatch, arse up in the air while kneeling on the radiator core support. Easily accessible with no other parts requiring removal. Bolts have a 10mm head. Use a ratcheting spanner for ease. (side note: i have removed the coolant lines to both throttle bodies so there might be some hoses in the way for stock cars).
So far for me, the results are promising. SRM works better than ever. No jolts between shifts even with sloppy pedal actuation, exactly as advertised. Crisp throttle response. Perfect idle. I will report back if/when i re-encounter my issue. Thanks everyone
