I'll throw this out there since it sounds a little similar to a problem I had, even if there are no codes.

I have had a problem with a similar symptom but always got *some* kind of code, even if it was misleading. Usually it was a CAN communication fault between the ECU and PCM P1797 or a security challenge fault with the ECU P1260.

This was happening pretty regularly is my case, the stall while driving, and there was no rhyme nor reason to when it would occur. to make it worse, nothing about those two codes should ever shut down the engine at 70mph.

One time the car quit on me and wouldn't restart, which is usually a bad thing but because of this I FINALLY got a useful error, for a TB position tracking problem. If you look in JTIS the response form the ECU when this occurs is to shut the fuel injectors off, exactly the symptom I was seeing. I wiggled the wiring and she started right up.

So, long story long, intermittent throttle position errors can cause strange behavior, so you might try checking the wiring harness for damage and cleaning the connectors.

It's hard to establish causality without some kind of error code, but cleaning connections is never a bad thing to do on these cars.

 

when you say do this and clean that could you explain more,and also i am not too clever with the abbeviations

 

Here's a link to the JTIS section on the 4.2 Litre Engine Management System. It's on my MediaFire account because the filesize is too big for a forum attachment:

http://www.mediafire.com/view/38f2ia...e_Controls.pdf

It has some useful diagrams of all the components and explains the acronyms.

Graham

 

Sorry about the abbreviations.

The throttle body (TB) has two resistor tracks in it that the the engine computer monitors to keep track of the throttle position. The shutdown occurs when the computer gets an invalid value from one of those resistors. What I found was that momentary hiccups don't always get stored as the appropriate error code but will shut down the engine just the same.

I am suggesting to check the wiring and clean the connectors to the throttle body. No real way to know if that is actually your problem but it's something to try and as they say, cleanliness is next to godliness.