My ap2 100 000km have the same problems, battery, alternator, spark plugs news, valve adjusted, cold, start perfect, only when restart after fews minutes when hot!

 

I have a lightweight braille battery, no heatshield present.

I added oil to get it right to the F line, seems to actually have helped the problem for the most part. Im kinda suprised that half a liter makes that much of a difference.

Ill keep an eye on it over next couple weeks.

 

Battery's don't like heat - it's battery heat soak. Your battery, like mine, it starting to loose it's state of health. A battery can have 12+v but have a cell starting to slowly go bad inside.

My battery is ~3 years old and it starts up fast/quick in the morning, but if I try to start it just after driving it the engine cranks a little slower.

 

i have this problem and after putting a brand new battery in, it did Not change. Im supercharged but that shouldnt affect it, it should still be consistent. adjusting the valves seemed to help this.... im getting the head rebuilt right now.... because of the constant tightening of the intake valves! ill see when i get it back if its any better

 

After reading your descriptions, I don't think its the same issue I had. For me, cold starting was perfect, but once the engine got warm, it wouldn't crank strongly at all, as if the battery or starter was weak. However, if I kept cranking it, the cranking would speed up and eventually fire. Once the engine was cold again (approx. 15 or 20 mins) it would start perfectly. It was as if something inside the engine was resisting the motion of the cranking once everything had expanded, and the battery/starter wasn't overcoming it.

 

Have you ruled out flashpro tune?

 

It is possible I suppose that it could be the battery, I will probably buy a new lightweight battery next year, going to try odysey.

I dont think it would be flashpro tune cuz that would happen more to when the tune was done, not start up a year later right?

 

Brad you are due for a valve adjustment, particularly given the issue with overly-tight valves on 06+ s2k's. I would do this asap.

Is the oem heatshield missing between the battery and header ?, if so get one installed asap as batteries don't like heat and being that close to the header will make a big difference when the engine is hot, and it gets worse in hot temp conditions.

Run a 1/2 bottle of Redline fuel injector cleaner with a full tank of fuel. It is one of the few fuel injector products that is actually effective enough to work with one treatment (one bottle does two tanks of fuel on the s2k), it also contains an upper cylinder lubricant which has some added benefits.

I've had various forms of slow starting in the past, it seemed to improve once I got the engine heatshield issue addressed and running Redline fuel injector.

 

I would think so but I'm not sure what type of learning the Ecu does

 

Here's your problem, temperature, and humidity have a big influence in the way the car runs, and this year is not at all like last year. Also do you have egr blocked off by any chance?