Tell me about shunting
Discussion
Read up on stepper motor first, often bad idle high or low revs plus shunting can all be caused by the stepper motor being sooted up and or just worn out.
If you remove it and give it a good clean that is often enough to settle idle issues.
Put some PTFE tape around the thread for an air tight seal when re installing in the Plenom.
If you remove it and give it a good clean that is often enough to settle idle issues.
Put some PTFE tape around the thread for an air tight seal when re installing in the Plenom.
Classichims said:
Read up on stepper motor first, often bad idle high or low revs plus shunting can all be caused by the stepper motor being sooted up and or just worn out.
If you remove it and give it a good clean that is often enough to settle idle issues.
Put some PTFE tape around the thread for an air tight seal when re installing in the Plenom.
Thanks AlunIf you remove it and give it a good clean that is often enough to settle idle issues.
Put some PTFE tape around the thread for an air tight seal when re installing in the Plenom.
I will dig the bible out, hoping it has some info removing the stepper motor. The issues are between 1500 and 2000 revs, makes driving around town a little ropey!
No worries. I've gone from "stepper motor"oh my god that's bound to be beyond me to doing it in my sleep.
Matt, so your looking in the right direction
Open the bonnet, you'll be standing on the right hand side of the car,
Look directly at your engine and follow the rocker box to the rear of the engine,
Now look up and to the rear end of the Plenom,( that's the big alloy bit on top of the engine)
The stepper motor is just below the window mesh, it's a large looking nut with an electrical. Connector at the end of it.
That's the stepper motor and it just screws straight into the Plenom body.
It'll all come clear in the morning. Regards Alun
Matt, so your looking in the right direction
Open the bonnet, you'll be standing on the right hand side of the car,
Look directly at your engine and follow the rocker box to the rear of the engine,
Now look up and to the rear end of the Plenom,( that's the big alloy bit on top of the engine)
The stepper motor is just below the window mesh, it's a large looking nut with an electrical. Connector at the end of it.
That's the stepper motor and it just screws straight into the Plenom body.
It'll all come clear in the morning. Regards Alun
I am at the very bottom of the pile as maintenance capabilities goes and even I can do this job.
Take a look here :
http://www.car1.clara.co.uk/tvr/stepper.htm
Take a look here :
http://www.car1.clara.co.uk/tvr/stepper.htm
The old posts are still valid- the fundamental reasons for it don't change. There is a multitude of reasons for it, as its basically bad burn in the combustion chamber. This can be contributed to by mixture, ignition or cam timing / duration / overlap causing contaminated inlet charge. The current 14CUX ECU tries to tightly control the mixture for emissions, but its not really suited to a tuned engine at low RPM, so fitting an after market ECU gives you more options to tune the mixture. Running a bit richer seems to help, or run the non catalysts fuel map- but this can roast the catalysts if you have them fitted. First make sure all the service items are good and the timing is spot on to get the best burn. It looks like TVR have tried to put more fuel in at the shunting point in the mapping in the past if I read this fuel map correctly- you can see the red bump in the map at around 1700 rpm, but the ECU will over ride this anyway to keep the emissions low.
I suggest getting the RG software and cable from blitz as a first step to understanding where the problem might be.
Lots of people have had the same issue (including me) and have gone down the route of 'guessing' what the problem is by changing ignition components etc., and while you might be lucky it can be a frustrating business.
FWIW I eventually discovered a fault code (well 2 actually) logged in the ECU which pointed to the fault and in my case it was the TPS. You must remember that a lot of the sensors in your engine will be old and no longer giving the ECU the correct information particularly at the 1800-2000 rpm range where we want to be a lot of the time.
Alternatively, drive it like you stole it and miss out the 'civilized' moments!!!
HTH
Lots of people have had the same issue (including me) and have gone down the route of 'guessing' what the problem is by changing ignition components etc., and while you might be lucky it can be a frustrating business.
FWIW I eventually discovered a fault code (well 2 actually) logged in the ECU which pointed to the fault and in my case it was the TPS. You must remember that a lot of the sensors in your engine will be old and no longer giving the ECU the correct information particularly at the 1800-2000 rpm range where we want to be a lot of the time.
Alternatively, drive it like you stole it and miss out the 'civilized' moments!!!
HTH
Driving technique does it for me after a bit of practice. Keep RPM above 2000 in higher gears. At lower RPM don't coast at steady throttle instead use throttle on then throttle off, then throttle on then throttle off. Easy when in the habit.
To thoroughly clean inside of stepper use the Blitz technique according to rV8r resources.
To thoroughly clean inside of stepper use the Blitz technique according to rV8r resources.
EGB said:
Driving technique does it for me after a bit of practice. Keep RPM above 2000 in higher gears. At lower RPM don't coast at steady throttle instead use throttle on then throttle off, then throttle on then throttle off. Easy when in the habit.
To thoroughly clean inside of stepper use the Blitz technique according to rV8r resources.
I used to have to keep up reasonable revs before I overhauled the ignition system (new plugs, extenders, leads, rotor arm, coil, ignition amp and fuel pressure regulator) and now it will happily pull from 1200RPM in 5th, not that I'd want to, just to say it can now do it without shunting.To thoroughly clean inside of stepper use the Blitz technique according to rV8r resources.
Since the overhaul, my fuelling seems to be better according to RoverGauge as well.
A900. Mine will only shunt when in 4th/5th gear at at a steady coasting throttle at 1200rpm. Mine and yours pulls away without shunt at 1200 with some throttle ON. There is a difference, see my previous ON OFF post technique. Repeat, keep revs above 2000. TVRs are not for a COASTING throttle at low revs IMHOP. Good luck and cheers.
As yKnot said "drive it like you have just stole it"
As yKnot said "drive it like you have just stole it"
Edited by EGB on Sunday 8th June 13:06
Apologies, I wasn't making it clear, I can hold the car at a constant throttle at 1200rpm with no shunting as well as pulling away. No on/off needed. This wasn't the case prior to the new parts.
I totally agree though, these cars are not for low revs though, take it up the rev range and enjoy it.
I totally agree though, these cars are not for low revs though, take it up the rev range and enjoy it.
A900ss said:
Apologies, I wasn't making it clear, I can hold the car at a constant throttle at 1200rpm with no shunting as well as pulling away. No on/off needed. This wasn't the case prior to the new parts.
I totally agree though, these cars are not for low revs though, take it up the rev range and enjoy it.
Thanks Karl. Good info. Were both happy. Have a RG to play with now, better than watching East Enders! I totally agree though, these cars are not for low revs though, take it up the rev range and enjoy it.
pwd95 said:
Deffo down to the old clockwork ignition system. Mine used to be a bit crotchety low down at low revs but now with the CANEMS distributor-less system it's perfectly happy at 1000 rpm in 5th. Even pulls away smoothly as you open the throttle.
Yes the way to go for satisfaction. Also with EMERALD and throttle bodies. Together with servo assisted throttle. All at a price. Happy with my clocks for now.
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