Here is my idle after installing my engine. I have two codes. p0037 and p0410. The MAF sensor is 6 months old, but I have the original oxygen sensor, that was in my engine with the water in my exhaust. I am almost betting on the o2 sensor being rusted and all, but don't know if it has anything to do with the idle. Watch the video fully, as it dies as it warms up, when I start it again, it does the exact same thing. 750RPM then 1250RPM then dead. until it warms up fully and does the fluctuating idle for about 5-10 minutes then its fine all day.

 

Hunting idle.....often the clutch switch

 

yes i did do that Charles. My battery was also unplugged for 3 months, and my car usually doesn't run right for a little while after that, but it has been 400 miles now, still idle is sporatic.

 

On the clutch pedal? I did replace the clutch pedal right before my engine overheated. Is it the switch that you have to pull out all the way for it to auto adjust?

 

There are 2 on the clutch pedal....I think it is the one that adjusts that causes the problem. They are cheap to replace either way. I think you can test them with a jumper wire /unplugging them to see if the problem goes away.

 

I will have to try that then, just to help diagnose. Why would that have anything to do with the idle of the car? Isn't it just a safety switch for startup and cruise control?

 

It can cause a hunting idle just like that

 

Update:
Noticed that when the gas pedal is pressed just slightly it stops running, unsure if it removes spark or fuel or air, but it dies until foot is removed from pedal then starts to idle again. I have placed a video of it, but you can't see my foot. Also, once it warms up its fine, I have placed a video of it going from sporatic to normal. I haven't had time to try the clutch switch, I am skeptical as to why the clutch switch would cause this but going to try anyway.

 

I have it printed out at least the engine portion and all accessories and such, but I haven't rpinted that part out yet. That helps out alot, would it need adjusted or just replaced? If I short out the connector would it "fix" the issue? I am going to try this tonight if I can find time to do it. It doesn't just do this at idle though, as shown in the video, but still could be contributing.

 

Well, while I was at lunch I disconnected both switches and nothing changed, however, I did not jump the connectors since I didn't have any wire to do that with. The idle issue remained even with the switches disconnected. I don't think this is the issue. The P0410 issue I am having is sensed by the O2 sensor. The O2 sensor was flooded with water inside the old engine. Maybe that code and the idle issue is the O2 sensor? Any inputs on this thought.

 

According to the service manual there should be continuity on the air pump itself, which I just checked and there wasn't any. It said to replace air pump if no continuity. so that should fix that code, but the idle issue still stands. The disconnecting the switch did not change anything. After I checked continuity I tried to apply 12 v directly to the air pump just to see what would happen. it sparked but did not turn on. Shouldn't it turn on with 12v applied?

 

I checked the continuity on the neutral switch inside the transmission. It was good so I connected it back. This was about a month ago. I have since put 3000 miles on the reman engine, and it still doesn't idle correctly. I replaced the spark plug wires as they were almost 4 years old, going to check resistance on coils (I know even if they read good they could be bad), and see if there is a bad one. Also, going to switch the coils around to see if symptoms change. Anyone have any other ideas what this could be?

 

After all this, I had 1.3LittersofFurry come help me out, we tried his throttle body which I was suspecting to be the cause of everything, and it ran fine. One symptom I had was when you unplugged the MAF with the car running, it actually ran better and didn't die. Put his TB in and all my symptoms went away, and for ***** we disconnected the MAF and it died, needless to say, it will be fixed soon and I will have a nice ride once again.

 

Hesselrode could you provide a little more information please. i'm having a very similar problem. Fluctuating idle and a P0410 code. When you said you tried "his throttle body" was there anything special about it or was it simply a new stock throttle body? Did you end up changing our the fan for the P0410? Any additional info would be greatly appreciated. Just purchased the RX8 on saturday and on Wed I get the CEL! It's a 07 automatic. The Cat was changed in December. Again thanks for any addtional info.

 

P0410 is the code for the air pump. To test it the service manual states to unplug it and read the resistance between the two pins, it should read continuity, or 0. I didn't fix this issue as I don't need the air pump. My catalytic converter is hollow on the inside. In your case, I would either take it to mazda and have them replace it under warranty, if you are under warranty, or replace it yourself. You could score one here for probably $100 or less. It is very simple to replace also. I think it may be three bolts and unplug it. The fluctuating idle, on the other hand was a different issue. My friend came over with his 8 and we took off his throttle body and put on my car. A test that helped me diagnose my car was, with the car running unplug the MAF sensor. Within 5 seconds the car should die. If it does not it is either a. the throttle body, b. the wire harness (due to not getting a signal to and from the ecu and throttle body.) probably not the wire harness, but my wire harness came out of the car with the engine and I cleaned it. So it was suspect in my 8. When you clear the codes it can go a few hundred miles before codes are thrown. They cleared the codes and sold it to you, just like they did me lol. The air pump just warms up the cat to operating temperature quickly or environmental purposes, but since you have a cat, I believe it also increases the life of your catalytic converter with our engines.

 

Thanks Hesselrode. I appreciate the quick response. Did you change out the throttle body or just clean the old one.

 

I think cleaning it killed it, when I replaced my engine I cleaned everything. Maybe liquid got inside and shorted the circuitry in it. I am unsure. I bought one from a member here and I will have it today. I did try to clean it again to see if it would improve, but it didn't change anything. It could be clean, but I suggest a rag with cleaner on it instead of spraying on the throttle body just wipe it off. It may not be the throttle body at all either, the only code you are getting is p0410? I would suggest driving it a few hundred miles and checking the codes again. Like I said before, sometimes it will take a while for all the codes to show up. I finally got a MAF code after I originally posted this thread, which made me start digging into it. Try unplugging the MAF while it is running and then go from there, if it keeps running I'm almost certain its the throttle body.

 

Thanks. The P0410 is all I have now. I only had the car for 3 days and took it into the dealer and politely requested that they solve the problem. I've purchased 4 cars from these guys and they are going to fix it for free. Don't know if it is covered under the extended warrenty I purchased or not. They said the problem is a solinoid that controls the airflow and the motor is fine. I'll check out the manual when I get home but I seem to remember that this was one of the troubleshooting steps for the p0410.

I should have noticed the engine idle upfront but in my childlike excitement of getting the car at what I thought was a good price I wasn't as critical as i should have been. I'll drive it for a while when I get it back and see if anything else happens. Again thanks for the help.

 

You should get a compression test if it's under warranty, unless it's Mazda they probably don't know what they are talking about with the 8, half the time Mazda doesn't even know.