Yes I know...I've searched and searched but haven't found a thread that sounds right. So here we go:

2006 6spd. 50,000 km.

She's run mechanically perfect since I got her. Like clockwork.

Anyways, all of a sudden a month ago I came back after letting her sit 4 days and she started giving me a wierd idle. Not rough really, not stalling. It revs up to 2,000 (as normal) then drops to 1,000 breifly before revving back up. Every 5 seconds, very rhythmaically. No dash lights, nothing. It keeps doing it long after the engine is warm, but slowly goes away over time (rev up to 1750, then 1500, then 1000, finally normal 750). No hesitation on acceleration.

Only happens after about 4+ hrs of sitting, and then only when sitting outside.

Took it to the dealer, they said they had no idea what the trouble is but maybe it's the IAC. They did the 48,000 major and everything was fine. Suggested I take it back and see if it goes away after I take it for a burn on the highway; of course I had no objections .

After a solid backroad run, engine light now on a couple days later. Other than the stupid idle and dash light she runs like a champion. I'm taking it back in tomorrow but I'd like to hear from the real experts here first.

 

Where are you located? What was done exactly on the "48,000 major"....parts?

 

Knowing what the CEL code is might help some...

 

I'm in Halifax, NS Canada. Warm here lately, humid. The 48,000 km major is just what the dealer called the expensive check they did. I've been too busy with work to pay much attention to the car.

@Jon: I'll post the code when they (hopefully) run it tomorrow. I was hoping someone would have a lead on this without it, I guess cuz it's been running like that for a good month and a half without any dash lights. They found no faults a week ago. I wasn't even really expecting a light at this point.

 

Dirty MAF sensor?

 

The code just helps us to narrow it down some.
Not sure about Canada, but we (US) have places like Autozone who will read the code for free.
That way you don't need to deal with the dealer.

 

I guess the saga continues. The CEL went out late last night on its own. When I took it in today, they told me that the code recorded was for a neutral switch in the transmission being stuck for a while (P0850).

As of right now, the technicians at Mazda still have no sweet clue why she idles so funky. The IAC was just a guess, buddy told me he really didn' know if that would fix it so don't bother for now.

I'm worried if it doesn't get corrected it will get worse when the temperature starts dropping and the car will start stalling out. I also don't want them to tear everything apart only to tell me they still don't know what's going on. I'll try the dealer across town when I have time.

 

The neutral switch is easy to test...
https://www.rx8club.com/series-i-do-yourself-forum-73/diy-test-neutral-reverse-switch-200453/

 

Thanks Jon this is perfect. I'll probably jack the car up this weekend and giver a look.

Some other threads point to this switch as the culprit to the idle hunting so I'll probably just replace it. I'm a little irritated Mazda just read the code and sent me on my way saying the two are unrelated.

 

any suggestions for an '04 that won't start when warm?

 

Yes...
1) Search, warm issues have been discussed numerous times.
2) '04 and early '05 are known to have a weak starters and should be upgraded.
3) Warm start issues can also be a sign of low compression.

 

thanks, I'll try a search...just bought 04 for my son (age 17) and the darn car won't start except for when cool...the poor kid just left his one-day-old car at the shop...mechanic is excellent, but not familiar with rotary engines and multitude of potential problems...

 

Look at the starter and observe the label to see if its the original or upgraded.
This DIY will help you identify it:
https://www.rx8club.com/showthread.p...hlight=starter

This is why '04 and early '05 models need it:
http://www.vimeo.com/3653485

And you might want to consider taking it to the dealer for a compression test.
The engine is covered under warranty for 8yr/100k miles.

 

I checked the link, but it was for manual transmission...his is automatic... does it matter?

 

In the link (1st post) you'll see a quote from ASH8 detailing the automatic starter reman number.
But also makes sure its a good battery.

 

I need to take this thread back for a minute.

No resistance from the switch so I'm just gonna replace it. Do I have to drop the transmission or is there a way to get to it through the interior?

 

Similar thing here. My car is fine all summer, but when it gets cold my car will rev by itself like this once my foot is removed from the clutch. If I push the clutch it goes back to idling normal, take it off and starts to rev by itself again. After it is warmed up it is fine. I had this problem last winter also.

 

Exactly same with mine...any fix for this?...I've searched but can't find one..

 

I haven't found out what it is. It hasn't done it for a while. Unless it does something to hinder performance or gets worse I'm not going to worry about it.

 

How could is it? Because mine will get close to 4000 rpms when its below freezing but that's completely normal when the car is that cold. It's just the engine warming up