Jerky ride

[eel330]

Hello all. MY 400HC has never been that good at low revs and now when I am stationary it takes about 10 seconds for the idle to drop down from 2000 to 900. When driving at 2000 the car is jerky and at part throttle, but this is all fine when you give it some. I have cleaned the stepper motor and housing so they now shine, but this has made no difference and I'm now wondering if my stepper motor could do with replacing and whether the car is fighting against the idle at 2000rpm and below.

Any help is appreciated? Thanks

[mr_lash]

Hi,

I had a similiar problem recently where I hadn't been able to drive the car for about 3 weeks (before you start I tore some ligaments! ). I gave the car a good run out and soon everything was back to normal

[hut49]

Could be a number of faults (either single or more than one). Two strategies: start replacing things and end up with weeks/months of frustration as your replace most of the sensors, electronics etc or get a specialist with diagnostic/fault code reader. Maybe shell out a little more up front to do the latter but you'll save money overall and you'll get back to enjoying the driving rather than being totally distracted by trying to work out which component to replace next. Not much help I'm afraid but hope you get it fixed whatever route you choose.

[mowog]

see www.pistonheads.co.uk/gassing/topic.asp?t=229117&f=8&h=0

I had similar symptoms.......

D

[frankgilbert]

How old are your ignition leads if they are standard and over 5yrs old likely to be failing, also if your temp reader is over 6yrs old likely to be fured up;the temp sender costs about £13.00 screw out screw in -5min job High performance leads available from dealers,sometimes ebay.

[eel330]

Thanks for the tips. I replaced the temp sender last year, the leads were replaced at the last service 6 months ago along with the plugs. The bosch coil looks okay. I am gradually thinking I should treat her to a rolling road session. Anyone now of a suitable garage in the Swindin/Bath area?

[sgrimshaw]

eel330 said:

Anyone now of a suitable garage in the Swindin/Bath area?

Don't mess about.

Get hold of Mark Adams and book yourself in for a session when he's next at Cheltenham.

Top bloke!

Simon

[meeko]

My Chim 400 does that sometimes (more often than not). The revs gradually fall from 2000 to 900 but others it settles nice and quick. It always dips to about 800 and then straight back to 900.

I've replaced:

Ignition leads
Plug extenders
Dizzy Cap
Rotor Arm
Stepper
Coil
Thermostat
Checked the ECU for fault codes (there were none)
I've also changed the valley gasket which meant resealing the inlet manifold/trumpets/plenum etc. So I know there are no air leaks.

Would be really interested to know how you get on, but I'm really happy with mine as it does run smoothly - i.e. you can coast in traffic in first gear and no kangarooing. It is a little lumpy on a little throttle, but smooth when being blasted.

I live in Bath which sounds near you, so would be interested to hear if you find a good garage.