Jlsoccer8

I recently purchased a 2005 Mazda rx8 6spd. Car wasn't running properly when I first got it but did some work on it and got it running a whole lot better. Replaced plugs, wires, coils, cleaned MAF sensor. The only issue I'm having is that the car stalls when I first start it and take off then stop like at a stop sign. But if I start it and take off on the high way and don't stop driving it for about 30 mins the car will run perfectly. It'll idle almost normally when I'm at a stop light or stop sign as long as the engine is already warm.

NotAPreppie

I wonder if you have an odd vacuum leak or if your coolant temp sensor is bad.

Get an OBD-II bluetooth adapter and a smartphone app and have a look at coolant temperature, fuel trims and MAF rate.

Also, may not be a bad idea to see if your throttle body is gummed up.

Jlsoccer8

You're the second person that has suggested the that coolant temperature sensor might be bad. I also removed the throttle body to clean it but to my surprise it was clean as can be so I don't think that might be the issue. Anyways I'll go ahead double check for vacuum leaks and try and replace the coolant temp sensor sometime this week. Maybe even today. Hopefully that solves my issue. Thanks for the info btw.

NotAPreppie

Don't just throw parts at it.

1. Investigate.
2. Diagnose.
3. Repair.

If you're doing your own work on the car, you should get a bluetooth OBD-II adapter and smartphone app anyway.

Jlsoccer8

Got a cell the other day. Went and got it checked it came back P0410 and P0172. I'm not sure if I created the P0172 by revving the engine. where should I go from here?

Cody Helton

P0410 - Secondary Air Injection Circuit Fail
P0172 - System Too Rich (Bank 1)

The P0410 could mean a stuck valve in the throttle body, but seeing as how you've taken it out and cleaned it that is unlikely. It can also indicate a problem with your air pump. This should not affect how the car runs, all the air pump does is pump air (hence the name) into the catalytic converter at startup to warm it up faster and improve emissions. So unless you have a stuck valve, this shouldn't be your problem.

The P0172 im not too sure about, i'm no expert on the fuel delivery/control on this car but the possible causes for this code are-

A dirty mass air flow sensor overstating the amount of air entering the engine which may cause excessive fuel delivery

A bad oxygen sensor

A leaking fuel injector allowing too much fuel to enter the combustion chamber

A faulty fuel regulator, which may not be regulating the pressure of the fuel going to the engine as it should

A vacuum leak

A possible fault in the coolant system such as a stuck thermostat or bad coolant temperature sensor

Worn spark plugs/Coils

I had a system too lean code and all mine turned out to be was a vacuum leak and a dirty MAF sensor. But, when you clean the sensor use cleaner specifically meant for MAF sensors. I didn't and made my engine run terrible but after cleaning it with the right stuff it worked great.

NotAPreppie

To troubleshoot codes:

Foxed.ca - Mazda RX-7 Manuals

Click the link that says "2003 RX-8 Workshop Manual".
Click "Engine".
Click "ON-BOARD DIAGNOSTIC[ENGINE CONTROL SYSTEM (13B-MSP)]"
Search for your code. Click that link.

More info for P0410:
At cold startup, the car pumps fresh air into the exhaust manifold to help clean up emissions and ignite the cat. There is an air pump just in front of the washer fluid bottle and a vacuum operated valve. The vacuum for the valve is controlled by a solenoid mounted on the back of the upper intake manifold near the firewall (next to two other solenoids that control the SSV and VDI).

P0172 is a rich code. You're getting too much fuel for the amount of air that the MAF is reporting. This is sort of the opposite of a vacuum leak. Could be a leaky injector, bad MAF, malfunctioning fuel pressure regulator, or a few other things.

Jlsoccer8

I got rid of the P0140 code. Previous owner had connected the air pump backwards which blew the relay. I plugged it in the right way and replaced the relay so now the air pump work just fine. As long as the P0172 I can see that it could be several different things but rather than replacing all of the parts that could possibly be causing the issue is there any way to eliminate some of them as it could get very expensive to just start replacing parts?

NotAPreppie

I all I can do is point you at the FSM that I linked above.

Jlsoccer8

Okay so I did an experiment. I read that the P0172 could be related to a faulty upstream O2 sensor so I decided to unplug it and see what it did. Well the car drove and idled perfect. So I figured that if inreplaced the front O2 sensor that'd fix my issue. Well I went ahead and purchased a new one, installed it and the whole deal. Car still has the same issues when the new front O2 sensor is plugged in but as soon as I unplug it it idles perfect. What the hell is going on?

TeamRX8

iTrader: (25)

When you unplug the O2 sensor the pcm control goes open loop; runs rich, no feedback for AFR control etc.

You have to pull the battery ground cable for 20 minutes to clear the KAM memory and then reset the ESS profile (brake stomp procedure) and then it has to relearn idle on it's own after that swap. i.e. stop f'ing with it for a while...

Williard

iTrader: (18)

You could also disconnect the battery entirely and hold the brake pedal down until the lights go out...
Then do the brake stomp after you've reconnected.
Same concept, same end result, less wait time.

Travis