Hello I'm helping my friend with his 2003 Mazda RX8, I used my Torque app on my phone to pull the codes from it, I got "P303, P302, P0200" and I also got two codes that I cant find any info on "P3701, C3100."

We where able to get the car started but its a rough idle, and the car will run for around 1 min, then just kill it self. We can get it started again with lots of cranking it will finally start, we also have to jump it with another car as the excessive cranking kills the battery. We thought that maybe the cylatic converter might have clapsed on its self, so we pulled it off and still the same thing.

Has anyone ever had these issues and can recommend the next course of action?

 

https://www.rx8club.com/series-i-tec...n-guide-26291/

 

Well, do you know any of the basics?

For example, coils, wires and plugs...?

 

We just changed the spark plugs and checked the wires. We where thinking to start with the fuel system fault code, thinking that if there was a fuel issue that would cause the miss fire

 

We know what those first three engine codes are, just not sure and as said before cannot find any info about P3701 and C3100

 

By "checked the wires", did you do a resistance test with a multimeter, and then compare that number to a known good resistance number? If it was just a visual check, it wasn't good enough.

You also didn't mention ignition coils. OEM ignition coils fail regularly, as early as 20,000 miles, with about every 30,000 miles being normal. Since I mentioned them and your reply did not, I'm assuming you didn't replace them either. I bet they are shot.

 

Knowing that there is a misfire is very different from knowing what causes it. The RX-8's engine is run on a razor's edge. The slightest failure in a rather large list of parts and conditions can cause misfires.

See this thread: https://www.rx8club.com/series-i-tec...t-here-222280/

You will need to cover every point until you find it. Dismissing a single point of failure is probably going to end up making this a wild goose chase.

 

Thanks for the guide we will start there first thing tomorrow. We did not check the resistance though, we have the ability, what should the reading be? Pretty sure they are stock cables.

 

Google search: site:rx8club.com plug wire resistance

First thread in the results list: https://www.rx8club.com/series-i-tec...in-max-225586/

post #3:

 

Awesome, so my last bit is, what about the P3701 and C3100 codes, do you know anything about them? I've been trying to Google and find the info but have been unable to find anything.

 

Unfortunately, no. Only one of your CEL codes exists for the USDM ECU, P0302, which is rear rotor misfire. The US only has 3 misfire codes, P0300 for random, P0301 for front rotor, and P0302 for rear rotor. I've never seen any of the other codes in your list. The Mazda documentation in the US dealer network (I have access to it) for the RX-8 doesn't have any of your other codes existing anywhere on a text string search.

Incidentally, if you DO come across a EU CEL code list with definitions, please let me know via PM or something, I'm interested in getting it to flesh out the CEL Code page on my personal website.

 

I was using the free torque app to do an "unverified" code scan on it, its been sitting for a few days and I just bought the paid version of the app with way more sensor data, I'll try to pull the codes again.