Not sure if this has been discussed. But recently my 987 S has a pretty weak cold start. Doesn't appear to be a cranking issue because it cranks just fine. But once the spark hits the fuel it just sounds too normal like a regular car. I have a loud custom exhaust with no cats and it used to sound like the earth stopped whenever I started it. But now it's pretty dismal. I've done lots of work on it the past year and barely drove it. Had to charge the battery during all the work. I might think it's the battery but it cranks just fine. Any thoughts? I'm looking for any excuse to upgrade to an antigravity battery but I just don't feel it's the issue. I want that ferocious cold start again 😁
I doubt its the battery. Maybe a mouse nest inside the muffler(s)? How much has the car been driven since you noticed the issue? I'd get it out for a good spirited drive to see it you can clear the cobwebs (or whatever) out.
BTW, that powerful throaty sound on a cold start (for about 30-45 seconds) even happens, to some extent, with a stock exhaust. II believe it is a combination of ECU and various sensors that open up port(s) on the intake and exhaust. and raise the idle RPMs It is possible that your mods might of affected this logic.
Agreed, Im not sure how the battery could have anything to do with this? The cold start rumble is caused the the ECU temporarily changing the exhaust valve timing and fuel richness in order to rapidly heat the cats for emissions purposes. Its literally causing a fireball in the cats for a few moments, so even a perfectly stock car with regular quiet exhaust will sound more raucous for about 20 seconds or so on cold start
It's how I wish
PSE
sounded open all the time but going on another summer trip this year it's good they erred to being nicely quiet. As it is on the highway you are not listening to tunes unless you dial up ear damaging levels.
I've only driven the car for a few hundred miles. Mufflers are clear of any obstruction. I think it could be an ecu thing as the battery was disconnected for a long while. Maybe it just needs to relearn. Hopefully I'll get that sound back.
Do you have 30-45secs of high rpm rich idle on a cold start?
If not, the mixture may not be enriching properly.
After much searching, I found my
987.2
base
Cayman
has a thermister mounted on the passenger side engine bank between the intake port risers. It senses ambient temperature and, when it's nippy it enrichens the start cycle.
Costs $50 or so and a 10 minute replacement.
You can check the thermister by measuring resistance when cold (e.g. refrigerator) or warm (room temp). I forget which way it goes, but if it doesn't change, it's broken.
I do have high idle after initial startup. So I'm guessing the thermistor is fine. But thank you for the tip!
