Problem ahead

[lexi]

The C5 has had a minor thing going on a month now. Starts fine most mornings. Some mornings the Stop light stays on and the little red dot light as well.
It all goes off when a few hundred yards up the road. The light thing is sometimes accompanied by a misfire as it starts from cold. Like firing on 2 or 3 cylinders, then building up to proper revs. That produces a little smoke at tailpipe. Normally no smoke at all.
First off, I thought glow plugs, so changed them and still the same. Then fuel filter changed, no difference.
I wonder if glow plug relay could be intermittent. I will check. Tank pump is making the right noises. I should do a leak off test on injectors to make sure all are equal or thereabouts. Clean EGR maybe. The car runs great otherwise.
One day it misfired on start up. Then when started it did 200 miles. I will need to get a Lexia done on it to check what is good on it and what is not.
Meanwhile, any other suggestions welcome. IME these things get worse and then catch you out.

[RichardW]

Is it the high temp light that's on? Could be low water level. I wonder if the mis fire is a sign that the head gasket is on its way....

[myglaren]

Glow plugs shouldn't be active in this weather anyway.

[lexi]

Still cold up here Steve. Minus temps am.
Water level spot on. Have changed out coolant, new stat and water pump a few months back. 112k miles on her.

[jgra1]

coolant would throw an error on the display I think lads.. it always did on my Hdi (doesn't bother on the x7 though!! I found to my complete surprise when the matrix went cold once!)

don't know lexi..handbrake switch would throw the STOP on, but so many other things would to..

[lexi]

Yeah, the STOP could be a red herring and even a reset might clear that. Intermittent misfire at cold start is strange.
It may need to develop before nailing it. I have never heard a consensus on the 8v glow plug thing. Some say below zero, some say minus 5 before they operate. Funnily enough, this car is not starting any quicker with new glow plugs, yet 3 of the old ones were duff. 12v is on the bus bar, then it goes out a good few seconds after starting. This may be unrelated of course so I wont get hung on it.......just thinking out loud really.

[jgra1]

my GP light would flicker on for half a second on cold (below 0) mornings.. as said somehow I just don't think they are really needed on the HDI unless maybe -20 or worse..
the misfire is weird though..

[myglaren]

Still cold up here Steve. Minus temps am.
Water level spot on. Have changed out coolant, new stat and water pump a few months back. 112k miles on her.

Come to think of it, the previous C5 (I think, may have been this one) had a duff temp sensor.
When started in a (cold) morning it would show overheating and the stop light would come on, car ran quite rough.
Ignored it and after a mile it would all go away and run OK for the rest of the day.
New sensor fixed it.

[lexi]

On the thermostat housing Steve? Will check that out. Thanks.

[myglaren]

One of three - the green one IIRC.

[lexi]

Located it on engine and ordered a Delphi item at a tenner. Well worth a shot.

[c.morewood]

Let me know how you get on. I couldn't solve it on the Xantia till I got the water heater.. when she's connected up and the temp is below 3 or 4C she fires up lovely, but get progressively worse, when there's no mains power available to power the heater, and the temp drops down lower than 3C.

[lexi]

Will do Chris. Other DI engines seem to fire up from cold in an instant. I heard one HDI starting in the morning every day for a week when away fishing.
I thought it was cranking for too long. I said to owner about heater plugs. He had just replaced them! My HDI does not start any quicker than the old TDI.
Yet, you get an older Discovery (not advisable) and they start with a bang on the first turn.

[myglaren]

Cranking too long is usually a symptom of an ailing starter motor - if they don't spin the engine fast enough it can take ages to fire up.
Been there

[c.morewood]

Mine starts quickly enough when cold its just the lumpyness and white/grey smoke.. needs a couple of minutes to settle down..even then at 1200RMP and just below 3000 she misses till she's warmed up.. but she's an old lady and is bound to have some problems. I'd just like to get to the bottom of whats causing it other than the cold!