Heavy fuelling and grey smoke on startup from cold.

Hi Folks, 1998 V70 T5 Manual. As the title states when I start her up in the morning from cold she streams grey smoke that stinks of fuel from the exhaust and the tickover is lumpy as anything, once she has warmed a little (couple of minutes at most) the smoke clears and the exhaust loses its excessive fuel smell and the tickover sits solidly at 850rpm. Once the engine is warm she never smokes rattles or anything out of order. I know the ECU is on open loop mode at startup with a cold engine so can anyone suggest what may need looking at, this has been getting worse for weeks now. I ended a thread weeks ago where I was asking for help due to this plus something else, well I fixed the something else and assumed this was part of it, obviously this overfuelling when cold is separate to my previous issue. I have spent a fortune replacing parts on this car as part of a major service so all obvious things have been changed like plugs, leads cap and arm. Any thoughts welcomed. Paul.

Is yours a 97 model with a dizzy cap, if so i would start there.

Hi, Thanks, it is a 1998 and yes I have changed dizzy cap, rotor arm, leads etc. The car drives perfectly when warmed up and doesn't smoke at all, only when I initially start it from cold that it smokes, stinks and the tickover is very rough. All vacuum pipes have been replaced, new PCV system including associated pipework, I changed all this when I was chasing a fault that turned out to be my turbo actuator. I had a boost and fuelling problem and assumed they were the same fault, now that the boost problem is sorted it is obvious the fuelling is something different. All the best, Paul.

OOpps:speechless-smiley-6

What's the long term fuel trim reading after a run?

I would think that the ECU has to start somewhere when working out how much fuel to inject when the engine is cold (open loop). So it makes sense to use the long term fuel trim figure from the last run. It is an adaptive system and this is one of the adaptive settings. If you run on petrol only for a drive cycle does it run rich on the next cold start?

Hi Chris, To be honest it only occured to me today after my initial post that just maybe the slightly higher long term trim (due to LPG) could be being read at cold startup and used to fuel. Up until now I had been thinking that the ecu would in open loop refer to a base map setting and didn't consider that the base map would be influenced by the long term trim. If the LPG is running leaner than the petrol then the LPG will be pushing up the long term and then because the only time I run on petrol is on a cold startup it maybe using this figure for a base setting to fuel...or overfuel as the case maybe. I know that when I unplug the ecu even just for a few seconds my trims are set back to zero so I guess the easy test will be tomorrow morning before I start the engine I will unplug the ecu and reset the trims, then start the engine....if this sorts it then that will explain it (unless of course the fuel trims would on a long drive auto set at a minus figure in which case zero would be still too high LOL) Thanks again and I will report back either tomorrow night when I get home or the next day with my results ;-) Thanks, Paul.

I have the same trouble on my 850 AWD, but just on the odd occasion, it aint lpg, but the symptoms are exactly the same, lumpy, misfireing,tons of unburnt fuel and grey smoke, gradually smothing out to a normal run over a couple of minutes, I have recently replaced the dizzy and rotor arm and plugs due to another earlier fault which turned out to be the coil so thats been changed as well. dmw