KANGAROO HOPS!

[EGB]

Been running well until recently, but now has the kangaroos when trying to feather the throttle. Worse at low revs. Too bad to drive.
Welcome ideas how to proceed to fix. Can happen I believe to RV8. Thanks.

[zed4]

I believe this is called shunting, something my car doesn't suffer from at all luckily.

Lots of info on the forum if you search for shunting

https://www.google.co.uk/search?q=chimaera+shuntin...

Usually caused by incorrectly set idle control screw, faulty stepper motor, and can also be bettered with a better induction hose system apparently.

[Barreti]

Seems odd this has just started.

Have you checked your plug leads?
If one or more aren't quite connecting or damaged you will be getting a crap spark until you give it some revs when it will arc across, pick up and take off.

[rigga]

As its just started I'd say its electrical and something is breaking down, usual suspects leads, cap, rotor arm.

[Milky400]

a good clean of the stepper use to help mine out a little.

[ChilliWhizz]

Is the throttle cable moving nice and smoothly? If it's a bit sticky in the first few millimetres of travel it can cause you to start the kangaroo effect.....

[EGB]

Cleaned and reset stepper idle. Before the K hops started revs would sometimes drop to less than 100 and engine would stall. Getting good sparks, 15mm on Gunson Flash Tester. Fuel pump is working ok on start up. No shorting sparks seen under bonnet in a darkened garage even when revved. Will check with Rover Gauge. I believe Paul at FFG reported this sometime. Will send a PM.

[Hedgehopper]

When you cleaned the stepper did you also clean its seat...just as important.

When random things go wrong I sometimes find re-booting the ECU can help.

[james_c]

Hi, this is my first post in nine years of using this forum to keep the Tvr running as it should do. But an answer to shunting that I’ve never seen posted is what happen to mine. The car has always run fine with very little shunting at all, until the other week, when it barley started, kangarooed, shunted, would not idle nicely, stalled at junctions, basically ran like a dog but still had good power at the top. The reason was that a screw/s holding the vacuum advance onto the distributor had vibrated loose causing the lever to disconnect from the retard/advance mechanism. All now fixed and locktighted, now runs great with no shunting. Worth checking.

[blitzracing]

The ECU can make the car shunt if it cant control the fuelling correctly due to a sensor error, or something that alters the fuelling. You have a lot of unknowns here, and guesswork is not good.

[EGB]

Thanks every body. Interest much appreciated. Have reset ECU using battery cut off switch. No fault codes shown by Rover Gauge apart from just the once, not repeated, Low fuel pressure (23) Fuel pump making the correct noises on start up but will check connections tomorrow including the blue socket relay. Will send upload images of Rover Gauge readings when PH have got them working again.Yes we are in guesswork mode.

[Barreti]

james_c said:

Hi, this is my first post in nine years of using this forum to keep the Tvr running as it should do.

Bloody hell, that is some serious lurking james_c
Welcome aboard at last, and some useful advice for the OP to consider.
And now you've broken your duck you shouldn't wait so long to post again.

[OleVix]

I put in half a bottle of Redex last week, putting in the rest now (its enough for 2 tanks) the car feels less shunty and more eager. Guess cleaning the injection system isnt a bad idea

It may not be the cause of the kangarooing but it will help and its only a 5er

[EGB]

Latest Rover Gauge read out. Hope Blitz and Tvs can make comment and opinion on my roo stunts. Note the irregular idle. Thanks. Eddie.

Edited by EGB on Thursday 24th July 17:06

Edited by EGB on Thursday 24th July 17:08

[blitzracing]

2 things poke out- 1) try the AFM in direct mode- it should be 32-35% (32% for a 3,9- 35% for a 5ltr). Alsocheck the fuel trim in long term- the short term is not cycling around a central point, so its running rich all the time. This may be reflected by a 100% long term trim, which means its run out if adjustment.

[EGB]

blitzracing said:

2 things poke out- 1) try the AFM in direct mode- it should be 32-35% (32% for a 3,9- 35% for a 5ltr). Alsocheck the fuel trim in long term- the short term is not cycling around a central point, so its running rich all the time. This may be reflected by a 100% long term trim, which means its run out if adjustment.

Thanks Mark. Will do, when it get's cooler. Yes a plug is very sooty.

[EGB]

New Stealth cam and ECU Eprom fitted, linear rocket acceleration now!. Almost solved all previous issues. What a difference the Stealth and Eprom has made. Need care now even on strait damp roads when accelerating.
Can anybody identify the old worn cam. See pic of engraving on cam end.