When I start my 8 in the morning, revs are smooth @ ~1500-2000 for a few seconds, then I get 2 or 3 peaks to 3000 (approx. 1 second period of each peak), then smooths to nominal idle of 900 rpm.

My dealer tells me to expect the car to rev @ ~2000 for a few seconds steady, then down to idle revs. But I see these spikes that he can't explain.

Anyone else notice this phenomenon? Any insights as to what is happening and if it represents a problem?

 

I notice the same thing, though my "spikes" aren't quite 3000 (more like 2500-2700). Doesn't seem to be a problem.

 

My rpm estimates are from memory so your numbers could well be more accurate.

Why do you say "no problem"? I've never had a car go through this periodic rpm cycle on startup before .... I hope it's no problem, but so far, I'm just ignorant of what is causing it to happen.

 

FWIW, I remember the '89 RX-7 GTU I owned for a bit doing the <b>exact</b> same thing; perhaps it's a rotary ECU trick...

 

Not to 3K, but does happen to mine. Of course every little thing different in a new car is cause for concern, but it only does it maybe 3 times, then it's over. I'm mentioning it when I take it in anyway. Doesn't seem as if a new car should exhibit this 'erratic' behavior.

Maybe a little ECU tuneup would solve it.

 

Mine does the same thing early morning (when you hear it 'purr'ing)

I don't think its anything abnormal, my Toyota used to do exactly the same thing. Basically it all depends on engine coolant temperature (I think)

The cycle goes like this:

1. 2K for like 5 secs
2. 1.5K & 2K ~ 2.2K spikes (pretty fast)
3. Then goes down to 1.1K until the engine is fully warmed up.

As I said before, I have experience from my previous car. It used to do the same thing (except for the spike)

 

mine does if often on the first cold start of the day ; it's usually done by the time the 10 second wait-to-drive span is over. Nothing to fret about.

 

mine works the same way in the morning... i'm not concerned about it, it happens the same exact way every time so its probably an ecu program

 

mine spikes around 2k in the morning or when I leave work.
I guess its normal

 

Someone else mentioned this "spiking" after a cold start and said he used regular gas and it went away. I tried the same thing and the spiking also went away. I now use regular gas since I notice no difference in performance and the engine runs very smooth and quiet.

Word of warning though. I only have 2800miles on my RX-8 so if the compression improves as the engines breaks in, I may have to switch back to premium, especially if I hear pinging or other noises.

 

So you're saying that I shouldn't be such an old woman ...

Thanks for the feedback, I'll quit worrying about it. I will mention it to the dealer when I go in to get the newly released basepan installed.

 

FWIW, I've been using 87 octane for about the last 6 or 7 tanks and still have the up/down surge during initial warm-up (like this morning around 60 degrees). and another FWIW, Shell doesn't seem to increase mileage.

 

I dont think it has to do with the type of gas