High revs and pulsing revs - diagnosis required (please!)

[pincher]

I'm sure I have mentioned this before but I can't find the post - have been having issues with revs recently and the best guess so far is the Throttle Control unit that (I believe) sits in the dash somewhere.

The problem is basically this - start the car and the revs start off very high:

http://www.youtube.com/watch?v=62V7lrvZVQo

When moving, with the clutch pressed (such as when coming up to lights or a roundabout), the revs pulse and stay high before eventually settling back down to around the 900 mark:

http://www.youtube.com/watch?v=CiYqQQL8XK8

It almost feels like there is a choke stuck on - today, I was driving up a slightly inclined road that had speedhumps, in second gear with my foot off the gas - I got to the end of the road without needing to use the accelerator!

Am I barking up the right tree with the Throttle Control unit, or should I be looking at something else?

Edited by pincher on Tuesday 12th July 09:07

[Barreti]

Neither of the links go to anything TVR related. Just some festival recordings.

Edited by Barreti on Tuesday 12th July 08:06

[nawarne]

pincher said:

I'm sure I have mentioned this before but I can't find the post - have been having issues with revs recently and the best guess so far is the Throttle Control unit that (I believe) sits in the dash somewhere.

The problem is basically this - start the car and the revs start off very high:

http://m.youtube.com/#/watch?v=62V7lrvZVQo

When moving, with the clutch pressed (such as when coming up to lights or a roundabout), the revs pulse and stay high before eventually settling back down to around the 900 mark:

http://m.youtube.com/#/watch?v=CiYqQQL8XK8

It almost feels like there is a choke stuck on - today, I was driving up a slightly inclined road that had speedhumps, in second gear with my foot off the gas - I got to the end of the road without needing to use the accelerator!

Am I barking up the right tree with the Throttle Control unit, or should I be looking at something else?

Chris,
First port of call for me would be to clean the stepper motor.

Probably loads of posts in the Chimaera/Griffith forums about this subject and similar symptoms. Basically, the stepper is located on the rear of the plenum, drivers side, just under the mesh/scuttle. You'll see a large nut with 3/4 wires coming from it.
It's a case of undoing the nut, having unplugged the electical connector. This will reveal a small, dome shaped valve 'plug' with a spring behind it. It's then a case of cleaning the plug and the 'hole' where it fits with some carb' cleaner/solvent on a rag. Screw the assembly back in with some PTFE tape on the threads, plug the electrical connector in and that should be enough.

Good luck.
Nick

[pincher]

Barreti said:

Neither of the links go to anything TVR related. Just some festival recordings.

Edited by Barreti on Tuesday 12th July 08:06

Oops - that will teach me to post from an iPad!

Have corrected the links in the OP

[pincher]

Nick - I probably should have mentioned that it has recently had a new Stepper Motor (in the last couple of months) - at first we thought it might have been faulty but squeezing the feeder pipe causes the revs to drop as expected.

[pincher]

Bump for the evening crew

[C3BER]

I had the same problem as yours. Change gear and the revs increased which sounded like a knackered clutch until the revs dropped. It was very embarrassing to drive with it until I had it sorted.

I'm not saying it will cure your problem but my cure was a simple accelerator
cable replacement.

At the same time I had the temp sensor changed and the big fuse for unrelated issues. Hope it helps.

[pincher]

That sounds like a (cheap) option - will look into that. Thanks!

[Grey Ghost]

pincher said:

That sounds like a (cheap) option - will look into that. Thanks!

I've got a spare I can drop in that you can replace at a later date if you need one this weekend

[FlipFlopGriff]

Been suffereing this too along with stalling and more recently a drop off in power and mega overfuelling on one bank. Turn it off and start again and it is fine (other than the stalling and high tickover issue). Had the dissy changed (needed it anyway) along with new "proper" Lucas rotor arm, changed the stepper (it fell apart when removing) and swapped the ECU. Initial impression is that all is well and now about 20% quicker than before.

I'd clean the stepper and buy a proper Lucas rotor arm first (ACT sell them at about the cheapest price) - at least you'll have a spare if its not that. Then you can work your way through other items.
FFG

[pincher]

Grey Ghost said:

I've got a spare I can drop in that you can replace at a later date if you need one this weekend

Am in no rush - will order one at some point. Thanks anyway!

[pincher]

FFG - thanks for those suggestions. As I said earlier, the stepper motor is brand new but will check it again to be sure. I have a spare rotor arm that I purchased for my 'essential LM kit' pack last ear so will put that on this weekend.

Keep the suggestions coming!

[FlipFlopGriff]

pincher said:

FFG - thanks for those suggestions. As I said earlier, the stepper motor is brand new but will check it again to be sure. I have a spare rotor arm that I purchased for my 'essential LM kit' pack last ear so will put that on this weekend.

Keep the suggestions coming!

When did you change the stepper and have the problems occured since? There are some crap ones on the market so if you have a duff one this won't be helping. AnNyone local you could borrow one off?
FFG

[pincher]

FlipFlopGriff said:

When did you change the stepper and have the problems occured since? There are some crap ones on the market so if you have a duff one this won't be helping. AnNyone local you could borrow one off?
FFG

It was changed by a specialist, along with the chip when I was having some some other stuff done recently. It was doing it before but not quite as bad. I have disconnected the ECU for a while to see if that reset anything. And pinching the pipe the goes into the stepper causes the revs to drop as expected. I'm sure I can drop in on a friendly local Griff owner to see if he would mind swapping steppers for a quick test

[FlipFlopGriff]

pincher said:

It was changed by a specialist, along with the chip when I was having some some other stuff done recently. It was doing it before but not quite as bad. I have disconnected the ECU for a while to see if that reset anything. And pinching the pipe the goes into the stepper causes the revs to drop as expected. I'm sure I can drop in on a friendly local Griff owner to see if he would mind swapping steppers for a quick test

A few in Southend.
FFG

[pincher]

FlipFlopGriff said:

A few in Southend.
FFG

Even fewer tame ones

[sgrimshaw]

You can eliminate the Stepper Motor from your troubleshooting by disconnecting it.

When the car is idling nicely, as at end of first video, simply disconnect the wires leading to the SM.

[Del 203]

pincher said:

Even fewer tame ones

Sorry about the blurred pic but i was running over to try and get the dog away before he got bd by the mad man running around in a gay pink t-shirt !!!

Note roof on







Tried anything else yet Chris ?

Edited by Del 203 on Saturday 16th July 18:06

[pincher]

Not yet - that's today's task. Just waiting for you to take Dan for his morning walk so I can strip some more stuff off your car

I took the roof off aft the Angel

[Harrytsg]

Mine does this occasionally (surging reves when coasting), if i stop and restart the car it goes away.

Maybe its an essex thing?

Edited by Harrytsg on Sunday 17th July 11:16