Disable high Rev cold start

[mad_sb]

Originally Posted by regal

My car idles at 900 rpm from a cold start in the single digit (5 degreees F), is that not normal? maybe explain the long warm up time? The car is 100% stock.

nope not if you are talking about a soaked cold start. In other words, if the car sits over night you go out and crank it, the initial crank should kit up to 1500 rpm and hold that for 20 - 30 seconds before it drops out of the initial high idle. After that, the idle target is controlled by the coolant temp vs idle target tables. Depending on the ambient temps, and thus coolant temps, the 2nd stage high idle (before full operating temp) may be just under 1500 rpm or as low as the warmed up idle target of 750.. just depends on coolant temp.

Sounds like you have a tune that messed with the cold start routine or fault with the cold start system. Might also check coolant levels and make sure there is no air in the system and check your thermostat is not stuck open.

[regal]

Originally Posted by mad_sb

nope not if you are talking about a soaked cold start. In other words, if the car sits over night you go out and crank it, the initial crank should kit up to 1500 rpm and hold that for 20 - 30 seconds before it drops out of the initial high idle. After that, the idle target is controlled by the coolant temp vs idle target tables. Depending on the ambient temps, and thus coolant temps, the 2nd stage high idle (before full operating temp) may be just under 1500 rpm or as low as the warmed up idle target of 750.. just depends on coolant temp.

Sounds like you have a tune that messed with the cold start routine or fault with the cold start system. Might also check coolant levels and make sure there is no air in the system and check your thermostat is not stuck open.

Thanks I a ready changed the thermostat, wasn't it. In hindsite it reaches op temp at about the same spot every day. I bought it new though so I can't imagine the ecu being messed with. Will bleed the coolant it does point to air entrapment.


thanks.

[FR-S Matt]

Mine definitely idles higher when it is colder outside, (30-40 degrees) and idles much lower when warmer (60+). Figure it's just trying to get fluids up to operating temperature quicker based on outside temp. I wouldn't try removing this feature.

[Nevermore]

Yeah, mine will hit close to 2k idle on start up if it's really cold outside, and if I leave it idle I don't think it gets any lower than 1500 until I've started moving.

[troek]

its fairly well accepted that the extra loud period is just to warm up the cat. i dont give a crap about my cat, i just wana be able to start my car in the morning without feeling like a jerk, while enjoying a nice exhaust set up. i WILL figure out how to remove this lol.

[mad_sb]

Originally Posted by troek

its fairly well accepted that the extra loud period is just to warm up the cat. i dont give a crap about my cat, i just wana be able to start my car in the morning without feeling like a jerk, while enjoying a nice exhaust set up. i WILL figure out how to remove this lol.

Lol, I'm with you. The thing is the cold start logic is not exposed in the rom deff's yet. You can change the base ignition timing during the soaked cold start (stock is -15 i think but it has been a couple weeks since i looked at that param) and you can change the target idle once you have exited the soaked cold start.

But you cannot disable the soaked cold start logic yet or modify the SOI point during this phase. So, you end up over shooting the target high idle, taking longer to "light" the cat off and kick down to a lower fast idle, and triggering any of a number of CEL's from post start ignition timing error to idle control malfunction. You can turn off those codes but it still does not have the desired effect of going back to a more traditional cold start sequence.

I think it will require a rom patch to disable the logic.

[troek]

Yeah i hear ya, im just hoping someone will reverse engineer that part of the ecu so we can disable it.

[Kodename47]

It is possible with ECUtek. I have it on my car and I've put it onto someone else's car too. There's a fair few tables you need to adjust though to make it work properly.

[regal]

Originally Posted by mad_sb

nope not if you are talking about a soaked cold start. In other words, if the car sits over night you go out and crank it, the initial crank should kit up to 1500 rpm and hold that for 20 - 30 seconds before it drops out of the initial high idle. After that, the idle target is controlled by the coolant temp vs idle target tables. Depending on the ambient temps, and thus coolant temps, the 2nd stage high idle (before full operating temp) may be just under 1500 rpm or as low as the warmed up idle target of 750.. just depends on coolant temp.

Sounds like you have a tune that messed with the cold start routine or fault with the cold start system. Might also check coolant levels and make sure there is no air in the system and check your thermostat is not stuck open.

@mad_sb I changed the thermostat (OEM and the old one never ove heated anyway), bled it, the car still has the shitty stock 2012 ECU/ROM and after sitting over night below 15F it idles at 900rpm for 10 minutes it takes a about 13 minutes of driving 2k-4k rpm to fully warm up. The car is 100% stock. The temp guage works and holds steady at 50% once warmed up. At -3F one morning it idled at 900 rpm and didn't stumble at all smooth as butter.


I'm not about to go the dealer only to be told the latest flash (with the DI fix) is unavailable so I guess this is the final straw in getting BRZ Edit or trying rom/raider/ecuflash. Any other advice?


Thanks

[arghx7]

Originally Posted by regal

@mad_sb I changed the thermostat (OEM and the old one never ove heated anyway), bled it, the car still has the shitty stock 2012 ECU/ROM and after sitting over night below 15F it idles at 900rpm for 10 minutes it takes a about 13 minutes of driving 2k-4k rpm to fully warm up. The car is 100% stock. The temp guage works and holds steady at 50% once warmed up. At -3F one morning it idled at 900 rpm and didn't stumble at all smooth as butter.


I'm not about to go the dealer only to be told the latest flash (with the DI fix) is unavailable so I guess this is the final straw in getting BRZ Edit or trying rom/raider/ecuflash. Any other advice?


Thanks

Are you starting it with the engine in neutral or in gear (guessing it's a manual)?

[mad_sb]

Originally Posted by regal

@mad_sb I changed the thermostat (OEM and the old one never ove heated anyway), bled it, the car still has the shitty stock 2012 ECU/ROM and after sitting over night below 15F it idles at 900rpm for 10 minutes it takes a about 13 minutes of driving 2k-4k rpm to fully warm up. The car is 100% stock. The temp guage works and holds steady at 50% once warmed up. At -3F one morning it idled at 900 rpm and didn't stumble at all smooth as butter.


I'm not about to go the dealer only to be told the latest flash (with the DI fix) is unavailable so I guess this is the final straw in getting BRZ Edit or trying rom/raider/ecuflash. Any other advice?


Thanks

So, after sitting over night in 15 degree temps, as soon as it fires up it immediately drops down to 900 rpm? No 20 - 30 seconds of 1500 rpm loud fast idle before it kicks down to 900?

Once warmed up fully, does it idle between 650 and 750?

If it is doing what it sounds like your describing I'm at a loss. If it really doesn't do the normal cold start sequence it should throw a code for sure, possibly multiple codes. Since it does not sound like it's coding either, your best bet might be to take it to the dealer (as much as that sucks) if you can make it stock enough. Even if they don't fix it they can at least document it in case it becomes a bigger issue latter on. It would have to sit over night and they would need another car for a cold start comparison.

Lemme know if you figure out what the issue is, sounds interesting for sure.

[troek]

Originally Posted by Kodename47

It is possible with ECUtek. I have it on my car and I've put it onto someone else's car too. There's a fair few tables you need to adjust though to make it work properly.

i dont think these tables are available in RomRaider yet.

[Td-d]

Originally Posted by Kodename47

It is possible with ECUtek. I have it on my car and I've put it onto someone else's car too. There's a fair few tables you need to adjust though to make it work properly.

Care to share which tables?

[regal]

Originally Posted by mad_sb

So, after sitting over night in 15 degree temps, as soon as it fires up it immediately drops down to 900 rpm? No 20 - 30 seconds of 1500 rpm loud fast idle before it kicks down to 900?

Once warmed up fully, does it idle between 650 and 750?

If it is doing what it sounds like your describing I'm at a loss. If it really doesn't do the normal cold start sequence it should throw a code for sure, possibly multiple codes. Since it does not sound like it's coding either, your best bet might be to take it to the dealer (as much as that sucks) if you can make it stock enough. Even if they don't fix it they can at least document it in case it becomes a bigger issue latter on. It would have to sit over night and they would need another car for a cold start comparison.

Lemme know if you figure out what the issue is, sounds interesting for sure.

yes 900 from the get-go. The only thing not stock are 16" WRX winter tire wheels sans the air pressure senders. I think I may buy the equipment to flash to the latest factory tune as my only trip to the dealer was for that early CEL flash that had to do with idle. I want to be able to DIY as much as I can anyway.