Intermittent Chimaera fault. Seems to be only in cold weathe

[PhysDoc]

I have an intermittent fault with my Chimaera (daily driver) where it will lose power, cut out and kangaroo. Sometimes I can keep it running by depressing the throttle but as soon as I let it off it'll die. Other times it will just die and refuse to start again. It first happened around January last year a couple of times and I changed the coil, dizzy cap, ignition amp and fuel pump relay. None of that fixed it, as it did it a couple more times. However, it then stopped doing it and has been fine all spring and summer until yesterday after snowfall. Spent 3 hours on the hard shoulder of the M3.

Could be coincidental, but it's the exact same symptoms and could be related to cold weather?

Any suggestions/help appreciated. I'm considering a new fuel pump as it seems like it tries to keep running sometimes rather than just cut out completely.

Edit. Should add that it's a 1996 4L hc serp.

Edited by PhysDoc on Tuesday 30th November 19:43

[sixor8]

Have you checked the stepper motor? Failure to idle is often caused by this being faulty. But weather shouldn't really be an issue unless your water temp sensor is also not working.

[blaze_away]

I'd get yourself setup with RoverGauge then run it whilst logging data in RG then look at the data and see what happens when it goes wrong.

Other than that I'd be looking at bad electrical connections, earths and all control components (ignition parts, fuel supply) especially checking for vacuum leaks. If you can use a smoke detector and attach that to he plenum inlet and see if you have a leak somewhere.

[Paulprior]

Have you considered the other relay, I think it powers the ecu, you should be able to swap it over with your new fuel pump one, I had some very intermittent issues due to a bad contact in this relay base

[kevd]

I would check/replace the temp sensor that feeds the ECU (not the gauge) If this is not showing the correct temp the ECU may be overfuelling ie running on choke, leading to flooding or fowling of plugs. I guess that Rover gauge would show this up, or have a look at the type and colour of you plugs.

[Fez887]

I had this issue on an S and turned out to be a kink in the fuel line, combined with dirt in the fuel filter