Kangarooing

[Kev1976]

Hi all need some help please. Purchased my first chim 400 in march. Wanted one for 20 years. Love it. Never really had any problems with it. Recently there has appeared a very intermittent kangarooing effect. When it happens it can be so bad it's actually dangerous. When it happened I was in 3rd gear at 1500 rpm. With my foot not moving on the accelerator pedal the car stalls for a second then restarts repeatedly go about 10 seconds. This can happen in any gear. Almost like a power loss. No lights come on dashboard. No spluttering. Had a battery change 4 weeks ago. Checked battery compartment and no problems there. Code 44 lambda sensor came on so changed that but still same problem. Doesn't happen motorway driving and seems to happen when car is at its hottest. Changing coolant temperature sensor today but seems more electrical problem to me. Any help would be appreciated thanks

[phazed]

Sounds like classic shunting.

How to eliminate it if it hasn't been there before, I really don't know?

I have Megasquirt and make sure mine is pretty much dialled out by a mapper.. You will have to go down another route.

Someone will be along shortly.

[andy43]

If it feels like the differential and gearbox are trying to leave the car, and it won't stutter at higher engine speeds or throttle angles it could be shunting. If it actually properly dies for a second when hot it could be ignition amp or coil possibly. Mine died completely and I think it may well have been the loom itself as wiggling the ratsnest in the passenger footwell got it going again.
Do a search for shunting on here : http://www.pistonheads.com/search?SearchText=shunt... - it'll hopefully pinpoint the problem.
A lot of these cars do shunt to some extent, some drive around it, some fix it, some bin the whole lot (which I've just done - Emerald, thank you Mr Joolz - am chuffed to bits with it, just need more time to drive it now).

[ClassiChimi]

Sudden loss of power sounds electrical to me, coil, ignition magnifier, plug caps, check all connections incl the two wires at the coil are making contact etc.
What revs does this happen or is it random,.

[Kev1976]

Hi all thanks for responses. The fault is very intermittent and can happen in any gear mainly when speeding up. Let's say I'm speeding up in 3rd gear it will just die on me for a second almost like I have taken my foot off the throttle and then kick back in again. If I keep my foot on the throttle this will repeat quite violently for about 10 seconds every second. Could it be immobiliser related just a thought.!!

[andy43]

If it's when you have your foot it's not shunting - most likely as above - electrical/fuel/The Wrath of the Lucas God.

[glenrobbo]

One thing that may be worth checking is the ignition amplifier module fitted to the distributor. It is bedded with conductive heat sink paste, which can dry out over time causing problems, mostly at high underbonnet temperatures.
It has happened to a couple of our V8S owners whilst on tour in Europe. Ask Joe ( v8s4me on PH ) for details.
I believe it's a bit fiddly and requires a specially ground down socket to get to one of the small screws, I'm not sure what size, possibly 4.5 or 5mm?
The heat sink paste can be obtained from the likes of RS Components.

Good luck.

[Kev1976]

Hi all. Have been told the problem is been caused by the potentiometer there is a dead spot. Heavy throttle would go past the dead spot and not be noticed. Been fitted Monday so hopefully sorted then a nice blast up the M6. Worth remembering if it is the problem. Many thanks