high rpm cold start
 

since it got real cold here my rx8 has had a bit of a 'sputter' every 3 secs or so during a cold start until it gets to 1500 rpm but I only ever notice it after the car has been parked overnight. Maybe it's my fake coils with 3000km on them real set of C's on the way now.

But the car scared the shit out of me monday...
We had about 30cm of snow and that meant it was a snow day so at around 12pm I went to the underground garage where the car is parked which is right beside the door and the door was stuck wide open getting all this snow over my car.

I started it - it took off like a bat out of hell. It went straight to 4.5k all by itself and sputtering in the process. I don't even go that high when it's halfway to operating temp. It settled down and everything was normal. I've also read that this is a feature for the cat.

Here's what gets me though... It drove like a champ that day, power delivery was better, it just felt more alive. The biggest kicker is that it didn't even idle hard.

Now everything is back to normal meaning, it's idling harder, feels less responsive.

4500 rpm is definitely way too high, something seems fishy to me. Even under 0 degrees, staying out all night mine never exceeded 2500 or so. My guess is that something is causing the oil pressure to be considerably low and the car is trying to compensate or there is a vacuum leak or something. My suggestion would be to check oil level, check for oil, vacuum lines, etc. Sounds like it is getting too much air. Maybe check your leading plugs. Just taking a few wild guesses.

Say whaa .....

How does it know oil pressure is low?

I just topped it off with half a quart yesterday so it burned about half a quart in 700km.

It's only done it once on that day when it was below 0F. I've actually started it up after work at a similar temperature and it normally started at 2500 rpm or so.

should note that coils, sparks and wires were changed 3000km ago.

using royal purple 10W40.

I think maybe because we had a blizzard that day it froze my MS CAI filter? I've also read that the 4500 start is normal at incredibly cold temperatures.

I'll try not to hold that against you, but can't make any promises ...

It's more than likely some kind of vacuum leak, which at cold temps everything is either contracting ot getting stiff and not sealing well.

Oil pressure sender? I am assuming that its used for more than warnings lights, no?

Its a oil pressure switch not sensor.

How cold was it that day? Mine does the same thing if it's colder than -20C over night, but it's only in the 4k range for a second or two before it calms down. It does kinda wake you up when it takes off like that though. I also use a sticky heat pad on the oil pan as an alternative to a block heater, and it seems to help a bit.

Mine does the same thing. No problem starting whatsoever, but when the weather gets below -17c, it goes to super high idle (4000rpm) right from the start. I did notice that giving a tap of the throttle cancels it out and the idle drops back to an acceptable 2500rpm.

my fuel trims are within 3% variance so I don't think it's a vacuum leak. AFR commanded & achieved is 14.6 under 3700 rpm.

Probably not the best place for oil discussion but what's wrong with RP 10W40?

Synthetic is crazy expensive compared to non-synthetic, and it's totally wasted by being injected into the engine and set on fire. Since rotaries decompose oil really quickly you should be changing oil before it degrades, so synthetic is generally seen as a waste of money.

So basically it is bad because I am too rich for u guys... because I pay 20$ more for 4.5l

Royal purple - No advantage (actually a bit worse when tested) and costs way more. That's why

No, nobody gives a shit, team just wanted to point it out.

During cold starts the engine runs in open loop so fuel trims don't apply in this case

you can run any oil you want, but IMO RP oil is all marketing schlock. I've certainly run my share of them, but going to Walmart and buying a 5 qt jug of 0W40 or 5W40 Mobil1 is easy, cheap, and not any different result wise. It also helps me justify dropping $60/Liter for Castrol SRF brake fluid .... :lol:

I don't know for certain with the RX8, since it never gets that cold where I live (mine hasn't done it), but my '86 RX7 had an "Accelerated warm-up" solenoid that caused it to do this on cold starts. I think the reasoning behind it is to get the catalyst up to operating temp quickly (at the cost of revving the shit out of a cold engine and wasting a bunch of fuel :nono:)

Just wanted to add that mine does the same thing, although it's only happened 2 or 3 times, when the overnight temp got below 10 degrees F, and the car had been sitting for a day or more. RPMs immediately rev to around 4K and it then backs down to normal after 20-30 seconds.

I don't remember this happening when the car was newer, so maybe there is something going on that wasn't present before. Although, we don't have many days that are consistently at those temperatures, so it's hard to keep track.

Actually just googled this and this tread came up it's been super cold here and mine has done this every day from a cold start. Jumps to 4k on key turn for about 15 seconds then slowly settles at 1k haven't had any issues thus far.

That's what it's supposed to do, I don't see how people don't understand this. Literally every car since the late 90s does it.