Acquired a TS V6 auto the other day and have run into a problem. It was doing the usual rough idle and miss caper so the following were replaced plugs, leads, rotor button and cap and idle stepper motor. Some improvements were noted but problem not entirely gone. Finally today decided to check for loose manifold nuts and found that someone had removed the runner assembly from the manifold and replaced it minus the gasket doh! Gasket no problem have spare but my problem is this: The butterflys in the runner housing should they be open or closed at engine off. Reason I ask is I have a spare manifold off the old Verada which is in good nick and it has the butterflys closed where the manifold from the car which looks crappy has them open and appears to have been tampered with where the motor mounts onto the gear. Workshop manual not very helpful by the way.

i had this issue yonks ago and got no answer. the best advice i can give is to do an ecu reset, as you will hear the gear wind over and then set.

Just to note i did this and my car was never the same anyways but noticably better

What I do with the "R" series is use an allen key on the TB end to shut the butterflies however the "S" series do not have this allen key set up so you will need to remove the TB, reach inside, close them, re attach the stepper motor and then put the TB back on

ECU reset will not always close them off due to the stepper assuming they are properly set in the first place

Thanks guys for that. Much appreciated.

Well butterflies set and ecu reset also stepper motor. She starts first time and idles smooth as silk at approx 850 rpm. Between 850 and 1500 cough fart splutter so am thinking throttle body needs a good clean out. Revs cleanly from 1500 upwards. Are the throttle bodys the same for auto without cruise and manual as I have a spare manual one that is like new.

So a quick update. Fitted another throttle body to this POS V6 and have the same problem. Replaced the following: Leads, Plugs, Air filter, ISC, Throttle Body (cleaned as per Mals sticky). Tested the following: all wiring to the ECU and checked ECU for dodgy/blown caps. All settings as per w'shop manual. Car starts fine and idles smooth as at 850rpm no flutter or miss. Light throttle gives a miss between 850 and 1500 then revs clean. Moderate to heavy throttle gives an induction sound as if the motor is gasping for air (low raspy sound if you can get the idea) then picks up and revs cleanly. As car warms up the miss becomes less pronounced but is still there. Cant road test as is unreg but seems to be ok up and down driveway. Any ideas guys before the financial controller has my you know whats in a vice?

Get an unregistered vehicle permit, put some clean high octane fuel shell premium, bp ultimate 98, etc and a good quality bottle of fuel injector carby cleaner and give it a flogging...Not rev the rings off it but I put penrite in it and gently pulled her to the rev limiter 1 and 2 then cruised in D O/D off. I'm curious has it been sitting and what colour were the plugs you pulled out I'm wondering if it is leaning out ?

But maybe before you do that let a more experienced person comment I have had limited experience I'm still used to carbies and points LOL

possibly burnt out valves in head will give very similar results as what you describe here.it may not be anything you have replaced and burnt out valves will show up as different colurs on the plugs 1 will burn blacker than the others