Fuel Mixture With Aftermarket Parts

[eppo37]

I have had problems with my 8 not running well for a while now. Mazda ran a diag a couple of times, and it always looked like the problem was with my fuel mixture. The car wants to run too rich. I installed the RP Supercat on my 8 back in September and didn't start having any issues untill about 2 months ago.

I pulled the supercat off and reinstalled the OEM cat a few of weeks ago, and cleared both the NVRAM and the KAM. (I only did this because Mazda kept blaming the aftermarket part) But as I expected, the problems didn't go away. Even after driving around 300 miles (mostly interstate) on the car after the reinstall. So I let Mazda have the car for a couple of weeks while I was out of town. I got the car back this morning, and it does seem to be running better. But no more so than it does every time I reset the NVRAM, which is always short lived. Mazda is saying that because the PCM learns progressively, it needed longer to work through the bad information the supercat had been sending it.

So here is where I'm looking for some input from the forum....
1) Does it sound like Mazda has a legitimate argument considering the car ran fine for 4 months with the supercat installed?
2) Has anyone else had a similar issue with the RP Supercat, or any aftermarket converter, after installing it on their 8?

I'm driving to Oneonta for a funeral this afternoon, which is little over an hour in both directions. So I'll update my post after the trip to see if the car is still running better, or if it looks like Mazda just reset the memory.

Update: It looks like I was right. Mazda doesn't seem to have done much more than reset the ECU. It was as bad yesterday as ever. It even reminded me of a couple of symptoms that had slipped my mind:

Very sluggish throttle response

Have had to drop down to 3rd to accelerate uphill - when driving around 50mph+

almost stalls at red lights - and has stalled a couple of times

Coverter gets pretty hot

Car backfires - particularly when I shift

When the A/C compressor turns on the RPMs drop, sometimes as much as 500 (tested this at low RPM though - specifically with car in neutral, dropped from 2.5k to 2k
-addition to that- when idling with the A/C on, the RPMs want to hover just above 500 and if I'm not mistaken it should move from 800 to 1k to compensate for the added drag

Car feels like it has what I can only think to describe as a "miss". It feels a little like someone touching the brake for a split second as I'm driving, The timing of it is completely erradic, and it's most noticable when I'm maintaining a constant speed. Generally with the RPMs holding very steady (between 4.5-5k)

Symptoms are always the worst in the afternoon when it's warmer. The car still hasn't thrown a CEL though.

[Herblenny]

Where did you take your car too.

I'm not an expert in 8 but possibly your O2 sensors might be damaged or might be bad. But that's just my guess based on what I been going thru..

[fikren]

Could be the o2 sensor, it could also be based on the flow of the supercat vs stock. Since the ecu is still reading off of stock programming, it may be riching up the fuel load due to the readings coming back. If you continue to have problems after you put the supercat back on you might contact racingbeat about their flash they do to see what they think and if their flash might fix the problems.

[eppo37]

Let me start by saying I am SO glad I took my car to Trussville Mazda! It looks like the 8 is finally going to get fixed. Now, lets get to the explaination.

So everything makes sense, I need to tell everyone what went on with the 8 back in January. My coil packs went bad and started dumping fuel into the cat. It got super heated (a few times b/w getting home the night it happened, taking it to Mazda, and Mazda test driving it). That's when I replaced the spark plugs, wires, and first set of coils packs It also fried the O2 sensor. Fast forward to the end of March, when all my problems started. Med Center told me my fuel mixture was off and the converter was the cause. But every test implied the converter was fine. I suggested the wiring harness could have been damaged by the heat way back when. They "checked" it, said it was fine.

Here is what I learned when Trussville Mazda called me yesterday to give me an update...
The tech told me he was getting a lot of "U" codes from the PCM (unfortunately I don't know enough to know exactly what that is). So after looking up the car's history, he checked the wiring harness on the O2 sensor. It seems I have been driving around with an incomplete electrical circuit, and no ground wire on my O2 sensor. They are going to replace the harness, the sensor, and the cat. Depending on what that does or doesn't correct, I might even get a new engine. Needless to say, I never got a compression test, but thanks to everyone for their help.