lawt

I had exactly the same problem on my 06 C2S and managed to fix it. The above posts are correct, there is a fault in the heavy gauge B+ cable on the engine that feeds power to the starter - the fault is a poor crimp on the lug that bolts to the starter itself. This was a known fault for 05/06 cars and the approved fix is a new cable at great expense as the cable sits under the rest of the engine loom so is very difficult to access to replace. I repaired mine in situ which took about 1 hr. I bought a 35 quid hydraulic crimp tool off ebay and pulled out the air box, the throttle body and plenum. I could then remove the B+ cable end off the starter (battery disconnected) and pull it out towards the rear of the car sufficiently to get the crimp tool on. With the very powerful hydraulic tool the crimp was re-shaped and re-secured to the cable. All back together an perfect, cranks perfectly all the time, hot or cold.

My MY06 997 C2S does all you have described. When cold it cranks slower than I would expect but never to the point where I think it's not going to light up. But stop for fuel when it's hot and I cross my fingers every time, so far it's not refused to start but the cranking is so slow that it hardly manages to beat the compression on the engine. Thankfully the engine itself is very willing to start no matter how slow it cranks. I've done all the usual, checked battery, changed battery, checked charging, left it on a charger - non of this makes any difference. Eventually I decided to change the starter motor and picked one up on ebay for £75. When I came to change the starter I discovered that (1) it was b*****y hard to get at the bottom mounting bolt and (2) the main cable and rubber boot over the crimp that bolts to the starter has severe heat damage. It's clear that there's a high resistance connection which is obeying Joule's first law and generating much heat. At this point I abandoned my efforts to change the starter and had a poor effort of additional crushing the crimp with mole grips. Initially this made a huge difference and I realised that the engine had been cranking slower than designed even when cold. For about 2 month it's been perfect but in the last week things have started to slow down again. Plan B is to borrow a proper hydraulic crimping tool (16 tonnes force) and really give this a good squeeze. I'll let you know how I get on. Plan C (if needed) will be to make up a new cable from the starter down to the junction with the long cable to the front end. Can anyone tell me where to find that junction - I've not been able to track that down yet.