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Old 14th February 2020, 07:33   #1
StewartIngram
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Rover 75 Connoisseur 2.5 V6 auto

Join Date: Jan 2008
Location: Chatteris, Cambridgeshire
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Default KV6 petrol poor starting from cold

Although generally my KV6 is fine, I have a couple of issues that are bugging me. With the warmer weather not far round the corner, I am thinking ahead of fixing these but could do with some help.
The car is a petrol model mk1 53 plate, in very good condition at around 90k miles, purchased around 14 months ago. I have since converted it to lpg - not my first - and would add that it always starts on petrol, switching automatically over to gas about 1/2 mile later.
1 - When starting first thing in the morning, it takes about 15 seconds or more of turning over to fire. Sometimes, as it initially fires, it almost stops then picks up ok. I would describe it as a faulty "choke", though obviously there is no choke as it is fuel injection! Once started it runs ok, though there is a bit of a "burbly growl" (hard to describe) until fully warmed up. During this time it will (un-noticeably) switch to gas with no change in performance. Once warmed up it purrs as normal. I would add that the temperature gauge, and heater, perform as I would expect (having lived with a KV6 since 2007).
2 - the second fault is probably unrelated, but I mention it just in case.
If I am following a lorry at say 50mph, and accelerate to overtake, normally no problem. But if I use a touch more throttle, I get the engine warning light flash. If I throttle back a tad, it goes off. But if I don't, the light then stays on. Probably a consistent 3500+ rpm. Bear in mind that I will normally be on lpg! When I check with my code reader, it always refers to a cylinder 6 problem; I have checked/replaced the plug & ignition coil there. I suspect that this is a fault with the tuning of the lpg, and when it turns warmer I'll give it a go with the laptop. But as the gas computer reads off the petrol computer, it just might be showing up a fault connected with fault 1? Yesterday I did a quick test on the open road, changing down to 3rd and switching back to petrol, with the revs kept up it seemed ok. This does point to the lpg needing a remap I reckon.

My gut feeling is that fault 1 is related to the petrol mixture available when cold - it is perfect when warm - possibly sensor related?

Stewart
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