Fuzznutz

Hey everyone, I am putting a K&N FIPK in my 2005 Honda S2K. I am also putting in a Mishimoto (3 core) racing radiator. For another 60 bucks I can buy a racing thermostat, but I was wondering how these would affect the mapping CPU? Any thoughts?

mmm...vtec

I think Im pretty proficient and confident in my knowledge of vehicles, but what is a racing thermostat? I hope its not one of those thermostats that open at a lower temp because those are bad news.

Fuzznutz

It does. It opens up at 60 degress not the standard 78 or 79. I'll stay away from it if you think that is best.

2003AP1

cooler isnt always better.

spectacle

Few things. No, chaging your radiator or thermostat will not require altering the ECU mapping. Why are you changing the radiator? Is the car overheating? Is the stock radiator leaking? If there's nothing wrong with it, upgrading it won't do you any good and is way more trouble than its worth.

spectacle

Uhh why are low temp thermostats a "bad idea"?? I've been running one for over two years, not an issue. Car barely hits 200* in stop in o in 95* FL weather.

jh4db536

Do you know what the thermostat does? You want a low temp thermostat free? Just remove the stock one all together and put the cap back on.

the thermostat helps the car warm up fast by bypassing the radiator until radiator cooling is needed, also minimizes the startup (enrichment) procedure elapsed time that your ecu controls, keeps the car a stable temperature (~90celcius) as normal operating temp so it can maintain target AFRs

because a car's ecu has a lot of fuel and ignition trims (for startup, warmup, normal operations) based on coolant temperature and when your car cannot "normally" maintain the standard fully warmed up water temperature (~90celcius) then it is having a bad day.

with a low temp thermostat, the car could be stuck in 'warm up mode longer than necessary' and running richer than it should be. The car will take 15+minutes to warm up opposed to 5 minutes.

the car will drop below operating temp on a cold day or if you are going freeway speeds. the ecu is not going to like it. the car will probably idle poorly because the Idle control valve behaves differently when coolant temps are colder than operating and if the engine really is warmed up but the coolant is not at operating temp so it will be confused.

i dont think it's a good idea unless this is a race car. then yes it will be fully tuned to deal with coolant temperature compensation specific for the levels of boost/nitrous/custom sized radiator, etc.

2003AP1

Not to mention the damage in the long term to the catalyctic converter.

mmm...vtec

So many reasons colder theromstat is bad idea. jh4db536 is pretty much right. The car will never be able to go into closed loop due to the colder temp. When that happens the ECU will stay in an open loop state spray more fuel than need causing high HCs. Just cause there is more fuel doesnt mean theres more power. High HCs are a good way to destroy ur cat.It will also not let the oil get to operating temp wich will lead to sludging of the oil and thats something u really dont want. The engine needs to be at its optimal temp to run as efficant as possiable. Thats why the factory has these thermostats at this preset temp. As a certified CA smog tech Ive seen the aftermath of these so called "racing thermostats" and they are not very pleasent.