Breakdown On Its Way!, breakdown on its way!

On the motorway today, doing about 70mph. All of a sudden the car learches, the Revs drops to 0 and then shoot back up again. It felt as if the car cut out in midflight but restarted again. Bit scary!
Does anybody have any experiance of this. Is it likely to be electrical or fuel related?

Cheers Mark

2.0 ct 1998 VSX S2

Hi Mark,

The intermittent problems are the wors to find and diagnose. I've heard of similar symptoms before and it turned out to be a dodgy power supply or earth to the engine ecu. The ecu will have been designed to operate at a voltage less than 12v otherwise when the starter is cranking on a cold morning and the battery voltage is at 9-10 v then the engine would never fire. With a dodgy feed or earth in the ecu circuit the voltage available could be low to start with. If you're driving alond with the lights on, rear heated windscreen, fan and wipers then its possible to drop the voltage that extra little bit to cause it to fail. Even the intermittent wipers just coming on to push it over the edge.

Other theories include being passed by some vehicle with an electrical problem emitting an illegally high level of electromagnetic emmissions and confusing your ecu. (I couldn't even begin to defend the logic of this)

As the doctor says ... come back to see me if it does it again....

cheers

noz

Cheers Noz,

Forgot to say its about the 3rd time its done it along with various odd messages from the dop matrix about low engine pressure when the car isnt running that dissapear after 2 seconds. Looking like an earth possibly.

Hi Mark,

I've had this problem on a number of occasions and it has been the relays in front of the ECU which have seemed to cause the problem in my case. I broke down in Wales at Christmas and when I looked at the relays one of the legs had gone brown and was melting the plastic. One of the relays works the fuel pump and so if that cuts out you stop then it cuts in again your foots still on the accelerator, maybe your pumping it and wham punch up the bracket and off you go again

I have also got a problem with the ecu which causes the engine to chug when cold I found that pulling the plug on the ECU and replacing it cures that problem although because I'm not electronically minded I have never found out what the real problem is. Sorry to butt in on your post Mark but could Noz tell us where the earth to the ECU lives and how it physically connects to the ECU? Because my ECU box isn't bolted to the carbody and I have stuck a plasplug in the hole to keep it still not wanting to rip out the under wing plastic protector to get to it.

Paulxmski

Hi Mark the problem you have with engine cutting out .
I had a very similar problem with my 2.1 td cutting out for no apparent reason.
The problem turned out to be the plipper type key (you know the remote locking and alarmtype keythat hinges out from the plastic case with the two buttons on)
When this key is in the ignition /steeringlock i was unknowingly knocking it with my knee and turning the key just enough to turn off the engine!!!!
The plastic bit hangs down quite low and with other keys hanging there as well it can create quite a big lever effect on the key.
the cure was to get a new standard type key cut and just use the remote key to unlock and lock the doors,using the new key to start and drive with.
The problem has never reoccured since .
Just a thought to consider.
Best wishes Bob

Thanks guys for your replys, the car has behaved over the last week or so. Weekend I will attack the earthing points and ECU connections just in case.
Cheers Mark