Start car, revs to ~4k RPM...WHY?
 

I start my car after it sits all night, and it wants to rev to 4k RPM or even more and as it warms up, the RPMs get lower (this can take a few minutes though of course).

I know it needs to warm up and all, but why so freakin' high RPMs?

In the dead of winter, I can see why it needs to warm up to a more reasonable operating temperature, but with the nicer weather now, it still does this.

Also, it's totally eating up gas at the same time. I see this as completely unneccessary.

In my Mazda3, cold starts would hover around 1k RPM, and slowly get slower as it warms up.

I guess my question is, is this really necessary? And if not, can I adjust something to get the RPMs down after cold starts.

If this is necessary, would 1k RPM not suffice to warm it up prior to driving?

Cheers,

Ed

4K rpm?

I don't remember my car idling anywhere over 2k rpm, then it usually drops to 1.5k and afterwards it idles as usual at 800-1000rpm.

Even when very cold (Canadian winter) it doesn't go over 2k-ish.

Is the car 100% stock? If not what did you change.

Stock except for a Typhoon CAI. It sits at 4k for maybe 1 minute, then slowly trickles down to 1.5 over the course of maybe 3 minutes. It's the ~4k that is just guzzling gas and as I sit there watching, I just wonder why.

The car performs as expected at all other times. Once warmed up, I idle at 500-1k RPM.

I just think this is a total waste as the car can warm up just as well at a lower RPM.

I'd hate to bring it in to the dealer over this as they will say either my CAI is the cause, or that this is normal operation.

I've had my throttle plate stick twice on cold winter starts. I start the car and the rpms start shooting up so I blip the throttle and it comes back down. I would attribute my issue to oil in the intake track/in the throttle plate bushings that gets thick in 0 degree weather.

Your issue could be an IAC issue. Maybe a vacuum tube is giving the wrong signal or is not correctly properly. I don't think anyone else has an Rx-8 that cold idles that high. Did this start when you put the CAI on?

I remember reading somewhere that someone had some of the plastic covers off in the engine bay and some water had trickled down on a sensor, leading to the same condition you're having right now until it was properly cleaned.

This has been the 'norm' for me since I bought the car. I know this thing likes to rev, and I also know from experience that a cold started car will idle higher as it warms, but this is just rediculous!!!

Yesterday it was in the low 20's (celcius), and the car was in the sun for hours.....I cold start it and the same thing happens. Idle at around 4k for a minute or so and then down to 2k and then 1k before I go....aaarrrgggh!

I'll check out the IAC and see if it looks clean and happy. I'll also look for rust near any sensors near the throttle body.

As for the CAI, I honestly don't see it being the cause.

Thanks for the replies peeps!

Ed

yeah this thing also happens with second gens and third gens rx-7! its the stupid sub-zero system where some geneius at mazda thought that that revving a cold engine is a good thing the warm it up faster! normally if you leave your car in gear or start it in gear it won't rev up or just tap on the gas before it gets to the 3000 plus rpms! another solution is to remove the subzero reservoir!