I think the owners manual covers this. Blue light on the dash the car I recall will have a self preservation throttle mapping and will not run hard or respond to sudden throttle inputs.

 

Thanks subiesailor. It definitely feels like something is amiss, this stuttering is not something that has ever happened before, and it's not particularly cold over here. It's like you gently feather the throttle and nothing happens, so you gently give it some more, and then it stutters and eventually comes in.

 

Does it do it regardless of fuel used at the time - petrol or lpg?

 

Only on petrol, as car won't switch to lpg until blue light goes out. Car is fine on petrol also after blue light goes out.

 

How are the plugs? If you remove to inspect, check if a particular plug seems cleaner than the others.

 

Plugs were changed 6 months ago, and the car had this occasional cold stutter before changing them. The problem is very intermittent, and the car runs perfectly when warmed up. Very frustrating not to get any codes.

 

Plugs should be NGK. If one plug looks clean/cleaner than the others, could indicate moisture in that cylinder which burns off when the car warms up. Any loss/usage of coolant?

 

No coolant loss, and plugs are denso. This problem was also present with previous NGK plugs. Im hoping to get a code but no luck so far. Previous plugs were fine when they came out.

 

.......and it doesn't do it all the time when cold, only about 1 in 10 cold starts.

 

I seem to have had some success with solving this. First I cleaned the injectors with RedEx, and added some archoil ar6200 to the petrol tank, this helped but the car was still not quite right. I recently disconnected the battery to replace damaged door mirrors, and took that opportunity to clean the front O2 sensor connector plug and socket, and also the crankshaft position sensor plug and connector. Both had quite a bit of crud accumulated on the outside. I used contact cleaner spray. Since doing this the car has run perfectly, has felt better, and today I plugged in OBDLink lx and seen that my IAM had returned to 1.00 , after being on 0.94 for quite a while. I'm not sure which of the above things worked, or maybe they all helped, but I thought I'd post the results, it may help someone in future. The crankshaft sensor plug (under alternator) seems to be in a place that attracts crud.

 

Forgot to add that I also cleaned the Pcv valve, though it didn't seem that dirty.

 

cleaning ones that got a lot of miles on them does not help, some of them get spring fatique and don't do what they should.

to me cleaning one is just something to do while waiting for a new OEM to come into ones hand. (aftermarkets may not do exactly what a OEM does, and that little thing runs the whole engine).

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that said seems like "all" the LPG Europeans here type of a need to swap plugs faster. :|

 

Yip, LPG is harder on plugs apparently, but not so much with iridium's. Mine has been on lpg since 25 k miles, got 55 k now, and changed plugs at 42k. Old plugs ( original NGK) looked fine. Plan on doing 30 k on new plugs and will check them.