Hey guys, having an issue with my s2000 which has 156k miles. Around 3 months ago, had to replace the battery (car wouldn't start at all).
Around 3-4 weeks later, I start noticing when the car is hot ( drive somewhere, turn it off for 5 min and then try to turn it back on), it cranks very slow. It as though the battery is bad but it isn't. I then swapped out the alternator since i had a spare. Thought that would fix it but same thing happened again today when getting something to eat. Within 5-10 minutes of turning of the car, it cranks extremely slow but eventually fires. If I wait 30 minutes to let it cool down, the car is fine. Can the starter be bad? Not sure what else to look for. Battery is good. Alternator swapped and still the same issue. When cold the car doesn't experience this issue. Also have a heat shied for the battery.

Any help would be appreciated.

 

your battery is either old or getting heat bogged. remove the heat shield and see if the problem goes away.

 

I'm going to say it's probably your coolant temperature sensor.

 

The heat shield has been there for over 2 years without an issue. But I can try and remove it

Regarding the temp sensor, I'm running a Aem ems so I'm not sure if it would effect it.

 

Ah, in that case my second suggestion would be the crank position sensor. Barring that, I don't know what else it could be.

 

There have been a few posts about this same issue, try searching them out.

I had a slower cranking engine a while back only when the engine was warm, but I changed the battery and starter at the same time. It immediately improved by I don't know which part helped most, I think it was the starter but I can't say for sure. I also had an exposed header at the time and I re-installed the heat shield on the header (Mugen).

Seeing as you have a new battery I would suspect the starter. Do you have an exposed aftermarket header ? , asthat can have an effect on the battery when fully hot.

 

Billman, any ideas on what this can be?

 

Defective battery (Unlikely), bad starter (likely), or poor connection (less likely), and that is it.

Nothing else mentioned affect cranking speed. There is no sensor in the car, AEM or not, that affects cranking speed.

Easy answer since you were very discriptive Most are not.

 

Great thanks for the answer. Guess I will look into getting a new starter. Now I need to see if I tackle this on my own or pay someone. Hear the starter replacement is a pita..

 

My mistake, for some reason I thought I read that it wouldn't start at all when hot. My vote is for a lazy starter as well.