A Bit Rough.

[johnny406]

Hey there, a little problem with my 406 especially when it's cold

It runs on LPG great, I get around 400-450 miles out 64 litres of LPG which is around 30-33mpg which is bloody good considering it's 46.9p here and only costs £31 to fill up.

I get about 40mpg on petrol on a run and around 33mpg around town.

I'm suddenly having a few problems, just been serviced by myself and I put some new Bosch Super Plus plugs in regapped to 0.7mm so it runs great on both gas and petrol.

Even before I serviced it the idle was a bit rough, it's a little better now however there is a little shudder at idle you can feel it through the car as the engine rattles away especially when cold, if you pop the bonnet you can see it move as if it is missing only at idle though, it's still quick does 0-60 in about 8-9 seconds on both gas or petrol.

When the choke is on and it's cold the petrol seems to run really rough too until it gets upto temperature and if you rev away down my drive for example it gets to about 2,000rpm hits a wall and splutters a bit and then revs and normally, perfect on gas maybe it's altering the fuel trims? I pulled the battery overnight to reset the ECU put the sputtering on petrol was still there until upto temperature, put the old plugs in same thing, regapped to 0.9mm standard still runs great on gas but still splutter when cold on petrol.

When you change to petrol after running on gas it takes a while for the ECU to adapt, if your running along because it takes again to accelerate then a mile or two more it's like a ferrari.

Is there a relay I could put on my petrol ECU to reset the settings each time I turn the key off but let me start when I turn the key, which will probably cure the starting problem.

Any ideas on how to cure the slightly rough idle, it's annoying me, no air leaks to speak of.

Occassionally the K light comes on but immediately goes off if you give it a rev.

The Idle Stepper motor is working great just been cleaned.

I can prehaps put a video on youtube to show what I mean with the engine rattle about.

Engine doesn't use excess oil

Spark plugs where tanish coloured as they should be.

[mjb]

Might be your coolant temperature sensor