Cold Start Flooding T350C

[craigcaf]

I have a new problem on my 2005 T350. I think it is overfuelling under cold start. Symptoms are if you do a three of four cold starts over a couple of days, the engine start to be difficult to fire and the plugs are getting very wet. To get it going I have to take the plugs out, dry them, spin the engine over with the plugs out and the fuel pump relay removed (to expel any excess fuel in the cylinders). Then it starts. It has done about 20,000miles from new and had a major service about 1000miles ago with new plugs then. The problem seems to have started after the guy at the local MOT station overheated it during the emissions test. His equipment was faulty and he had the car held at about 4000rpm continuously for about 5 minutes, bonnet down. Anyhow, this may or may not be relevant.

When you start from cold it smells of fuel which again seems to suggest overfuelling. I have reset adaptives and throttle position sensors, but it has made no difference. The car did pass the emissions test with both lambdas working fine.

Does any of this sound familiar? Any ideas where to look for a fix.

Thanks

[m4tti]

The fueling is driven by the TPS and dynamic adjustment from the lambda reading.

Are the lambda readings definitely correct and fluctuating as expected?

Check for air leaks at cold around the throttle bodies.

[craigcaf]

Lambdas going closed loop OK when warmed, but obviously inactive under immediate cold start until they reach their own operating temps. Will check TPS again. Off the top of my head they were reading 15% after reset but I will check they track up and down together as throttle is pressed.

I wondered if coolant temp signal could be the issue. Did have a coolant sensor fault logged after the overheat, but both sensors seem to be reading OK and within a few degrees of each other when warming up and at fully warm condition since then.