erratic idle when starting

[Christa53]

Hi can anyone help????
i have a starting issue with an 05 reg astra hatchback. with 67k on the clock and fully serviced. when trying to start car in temperatures below 15c the car starts but then drops revs and dies, it is erratic in idle when I finally get it started especially at junctions when it again cuts out on me and I have to restart it. it is like a jerking horse until it settles down and drives normally. sometimes when starting in conditions like this the power steering locks and it is hard to steer but again when the car settles down there is no problem and drives okay. my mechanic has checked it for any faults and even took it to the vauxhall garage to be put on their computer and no fault codes have been found. it has had a new battery, throttle body checked and cleaned just in case. had anyone any ideas on what is wrong? I have never had this issue with any car I have owned and it is literally driving me up the wall. ps the car is fine in warm/hot weather maybe I should move abroad

any help would be much appreciated

[BrassMan]

Any air leaks or unsecured hose connections around the inlet?

[stevensdrs]

Diesel or Petrol?

[itcaptainslow]

Has your mechanic checked the live data stream to see what the coolant temperature sensor is reading?

If it’s reporting an incorrect value then the car won’t fuel properly, especially when the engine is cold.

[wiliferus]

If it’s a petrol, cold start issues can sometimes be attributed to damp conditions.
For me, whenever I’ve had starting/running issues I’ve started at the HT leads, coil packs and plugs and then worked from there.
If it’s damp, the fact it runs ok when warm makes the think the heat of the engine is drying out the damp.
Check the leads and plugs. A liberal dose of WD40 around connections and go from there.

[Christa53]

hi it is petrol and it has been checked for near enough everything I am at a loss and so are the mechanics at both my own and vauxhall garages

[stevensdrs]

Does your engine have a coil pack. A cracked coil pack letting in dampness would cause these problems. Take off the coil pack and put it in a warm place to dry it out. Then refit to engine and if it starts okay you have found the problem.

[Lowtimer]

I would also suspect dampness somewhere in the ignition system is likely. Coil packs and plug leads.