Hello All,
I thank you in advance for the help!

I have an 07 CX7 2.3 turbo. The spark plugs foul after 100 miles or less of hiway driving. I've attached pics of my scanners live data read out. Shouldn't these be mainly in closed loop for efficiency? The data is from warmup to hiway driving. Scratching my head on why its mostly in open loop...no codes at all. Slight hesitation in fast idle. Stalls and sputters after plugs are fouled obviously.
Scanner graphs have the legends on the bottom left hand side.
The etc as well as map, maf, determine whether the pcm goes into closed loop. All check out fine. No codes triggered whe it finally does go in goes into closed loop for a short time. Was on the hiway on cruise control just fine before slowing down not volunteeringly to a max of 40mph. Sputtering when trying to accelerate. Cleaned fouled plugs, runs fine until fouled again. Through all of that, no codes. Pcm thinks that's just fine. Heavily leaning toward bad pcm because of the above

 

Too technical? Anybody?

 

I responding because your response here ^^^^^^
No it not to technical for me... but for you???
You are missing so many steps in diagnostic servicing I wouldn't know where to begin. And you just cleaning a fouled plug??? auh ok.

My best advise is go to a shop and have them run a diagnostic service and pull all the needed information .

At this point I do not see how anyone concludes it is a faulty ECU/PCM?

If you are interested in how to do a better ECUPCM information pull search my username and you will find many "repeated" steps on doing it the correct way!

Good Luck

 

No it's not too technical for me as I'm an ASE certified technician. Just not 1 response in 2 days so I assumed its too much i came here for ideas response, not take it to a mechanic....Maybe it's because it's a Mazda, idk. There's not much I left out. The plugs foul within 100 miles of driving. New plugs and coils. No lift or stft as it won't hit closed fuel trim. As you can see from the graphs I attached, the AFR are within range. In live data, that didn't show ect climbed with respect to temp which yells the pcm to go into closed loop. My pcm is fouling my plugs because it's not l going into closed loop. Map, maf, tps, ect, all in range where it should be. As you can see from my scan data, the pcm will briefly go into closed loop, where it should throw a code if there's a problem. But yet, no codes thrown when there's obviously a problem. 220 miles per I tank of gas and cleaning plugs is an issue. Any information anyone would like, ill get it.

I'll check the ecm link ur talking about. Would like to be thrown ideas for a solution. Thanks for the reply!

 

ok look... I see you are trying! and also ASE so here is what you need to do. Go into the ECU/PCM files for permanent DTC's. Then go look at your I/M. you should have 1 or more in fault. Then check the PCM counters for anomalous events, if there are nothing there then something is either no reporting correctly to your "pcm" , there is a bad connection (the main PCM harness) or then you could suspect the PCM

Please don't start swapping parts or replacing parts before you have concluded the exact problem or verified a part has failed.
It is also a very good idea to look at the Battery ground cable. Make sure it is clean and has good continuity.

ASE

 

Castillo, many years ago I was ASE certified, in 1999. I turned to engine builder, quality control, Gage calibration a few years after that. I do however work on all my vehicles/toys. Just stumped on this one. Never been sent to a shop going on 30 years. The coil did need replaced as it wasnt firing.
I finally had some time to look at the Mazda. There are no codes permanent or intermittent. However, there are 4 I/M monitors "not ready". I'll add a pic. Just needing to bounce ideas to a fellow gearhead as I'm stumped. Thanks for the input!

 

Well it won't let me upload the pic for some reason.

Monitors not ready after normal operating temp is reached are:
O2 Sensor
O2 sensor Heater
EGR
Evaporative System
Keep in mind the pcm is still in open loop even though at normal operating temp

I did replace the battery terminals on the cables as the idiot i bought it from had marine terminals on it. There's good contact on it now. I also unplugged the pcm, inspected all the pins to verify good contact and no broken pins.

 

You must be a night owl? lol I am off to bed as I get up at 5:30 am . But will respond to you finds tomorrow. Your post #6&7 should have had supportive findings but don’t. 🤔

 

Looking at all that you have done primarily from the last 2 postings of yours it is pointing like a problem with the ECU. You may need to consider getting a rebuilt one with a warranty?
It is not clear why your I/M are in fault and no DTC can be located. That generally means the ECU is corrupt. It is to bad your device cannot access the counters. That would confirm a bad ECU.

 

No sir I am not, I just work until bedtime I get up at 430am every morning...
I did find those monitors were "not ready", I assume because the pcm was still in open loop. I changed the battery terminals as i know how important a good connection is important for proper function of electrical components and values.