klatt

Hi All,

Haven't posted in a while, just because I haven't had to. After having the car for 14 years (2007 6-speed, 133k miles, 40k miles on Mazda reman) I generally know every little weird sound and odd idling / starting issue and have been through them all a few times. This one is a bit of a pain though.

A few weeks ago, the car randomly started idling goofy and wanting to stall. I checked the codes and there were P0172 (System too rich, Bank 1) and P0335 (CKP Sensor A Circuit). I had just driving through an industrial part of town with some bad roads after just raining so I figured maybe there was some metal on the ECC.

Pulled it off, seemed pretty clean to me, but I tested the resistance (normal) & cleaned it none the less. Did the 20 break pedal stomp and car ran fine for a bit.

I'm thinking now that was just because it had reset the sensor data and fuel trims because a while later it started up acting up the same way, except one more new code: P2097 (Post Catalyst Fuel Trim System Too Rich Bank 1).

Okay, so I'm wondering about an O2 sensor, though I replaced the downpipes sensor only a couple years ago. Either way, I figured I'd check the ECC one more time though since it's so easy.

Tested the resistance again on the ECC. Normal. Following Step 4 on troubleshooting P0335 (DTC P0335 ) I was able to see that terminal A (I think..) showed continuity on the engine block.

I haven't been able to get back out to work on the car but I've been checking the forums and the only person that I can see that's mentioned this specific scenario is here: https://www.rx8club.com/series-i-tro...ooting-252874/ however I don't see a resolution.

I see a lot about people saying that the wires for the ECC are shielded and super sensitive, as well as that they _aren't_ shielded.

Also, there are talks about having to replace the entire wire harness for the car, which honestly is not something I want to do, so I'm wondering if anyone has any ideas.

Can a new line be run? Can I pull that one out of the harness? I'm going to try to test the continuity to ground inside the car at the PCM like scitmon did in his thread above, but other than that, and the harness I'm going to look at the O2 sensors.

Any thoughts?

TIA all,
Frank

klatt

Forgot to mention that it was indeed running rich. AFR was running ~11 since the codes.

0-TO-100_Real_Quick

https://www.rx8club.com/series-i-tro...t-idle-194505/

klatt

Thanks, though I'm not sure if you saw above, that I've already cleaned the ECC and done the 20 brake pedal stomp (oil gauge blipped and all). Not my first time doing that but the issue came back, along with the O2 sensor code...

The other interesting tidbit is that I'm getting a ground on one of the terminals of the ECC which the shop manual says to look at first. The harness looks alright from what I can see....

0-TO-100_Real_Quick

I posted that link because it offered a few other troubleshooting items to look at, like coils, cat, plugs, MAF, O2 sensor, etc. Other people have had similar codes pop up at once, and turns out the ESS wasn't the smoking gun. If you're convinced the ESS is the culprit, keep going down the rabbit hole. Check continuity at different places in the circuit. If there's a short somewhere, you'll find it eventually, and then you'll have to replace either an electrical connector, the ESS, or a harness.

I'm not electrically savvy myself, but if it were me, I'd start with cleaning the electrical connectors for the whole circuit. Our power steering connectors are notorious for failing, and I'm pretty sure the ESS has very similar connectors.

TeamRX8

iTrader: (25)

then you should have known better than to go full noob starting a new thread rather than adding this to an existing one.
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klatt

Ah gotcha, thanks 0-TO-100_Real_Quick! Yea, I had been in that thread multiple times hah, which is what partially has me thinking the other O2 sensor or MAF, though I did just clean that with a new filter not too long ago - new coils, plugs and wires too all within probably less than 5k miles on them. What also had me thinking the ESS is because those other code says to check P0335 first if that is being thrown too.

I honestly didn't think the ESS could be causing the same issue again except for the fact that this time when I took it off, I tested the connection and with the short to ground Mazda says to replace the harness. Like I said, I hadn't been able to get back out to work on it so I figured if anyone had any experience with shorts to that sensor since like you mentioned, I'll just have to keep going a long and checkin - which I'm not looking forward to. Hopefully, I don't have to replace the harness.

True, and they just get brittle and dirty after 14 years of winters and summers in NJ. Next thing though will be to take a look through the circuit and clean connectors, then the O2 sensor and maybe clean out the MAF again since that never hurts.

klatt

While it's useful for ideas like real_quick said, his fix didn't work for me. He also doesn't have the ground short on the connector or P2097 for the 02 sensor.

TeamRX8

iTrader: (25)

sorry to break it to the “everybody get’s a 1st place trophy” generation, but neither you or the issue is exceedingly special


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klatt

I had a question. I posted a good deal of info. ¯\_(ツ)_/¯

Thank you for the information and the laugh. You saying that makes my almost 40 years-old, curmudgeon, grey-beard self feel young. I completely agree, too many trophies and too much entitlement in the world. Very few people are truly special and I'm sure none of them are posting on rx8club.com 🤣

0-TO-100_Real_Quick

Just remember to post up what worked for you, so you're not just another "full noob starting a new thread". Lol

Se7en8

I had the same P0335 issue with a rough idle. I checked continuity back to the ECU and everything checked out. The problem for me was a loose connection in the plug for the ESS. I just added a little solder to each pin to make a better connection and it resolved the issue for me.

Cheers
Mike

Meat Head

Glad you found a solution and posted the results. It helps the rest of us noobs when the loop is closed.
On the topic of noobs - it doesn’t hurt to start a new thread when many of the old ones contain pages of personality clash responses making a mess.

klatt

So, please accept my apologies for not posting my fix, but I just got it squared away a couple of weeks ago. In 2021, I had taken the ESS (I have no idea why I called it the ECC half of the time in this thread, ha) off and cleaned it. Things seemed alright for a short bit, but unfortunately, the fuel pump died before I could really confirm that the ESS issue was solved. Then I moved and got married, so, unfortunately, the 8 was sitting for a while until I had time.

I finally got it running, and the car didn't seem to have the issue anymore, so I was hoping it was a big thumbs up all around. I had even brought this thread up to reply that it was fine, but that I couldn't be sure of the specific cause. I had spoken too soon. I ran an errand on an especially rainy day, and the code came up again after running through some puddles.

I already had purchased a replacement ESS, so I put that on cleared codes and ESS reset....no dice.

Running through my previous thread, I had seen that I had previously been driving in the rain when the codes had gone off. It led me back to thinking that there was a short somewhere since it mostly happened when it was raining - water getting in some place that wasn't as sealed as it should have been. The ESS harness wires also looked a little worn, so I put some high-temp liquid electrical tape around where they enter the harness in an attempt to seal it. Cleaned the ESS harness connections, cleared codes and did the ESS reset. Codes came back after a bit.

Then I tested the ESS harness for continuity to the body and got a positive return on one of the terminals - BAD. Tested the continuity between the terminals on the PCM harness side - both showing continuity - GOOD. [If anyone has any issues reading the wiring diagram for the harness, let me know - I took photos of where I checked on the PCM harness.]

Since it was definitely showing continuity to ground on the ESS harness, I started to back-trace the wire through the engine bay. It was a PITA, but it goes up around the drivers behind the coil bracket into a larger wire harness. I removed the airbox + intake tube, as well as the coil bracket to make the wire easier to inspect. I found that a large portion of the plastic wiring harness loom had gotten brittle and broken. This section of wire was right next to the engine itself and looked to have been wearing against the engine.

I assumed it was periodically causing a short there when things got wet/dirty enough, if the engine was torqued to the right side to a certain degree, or who knows. I was running short on time/light, and it was difficult to see this area but I thought that I could see where the wires were exposing copper. I wasn't entirely sure, but since I was short on time, I decided try addressing that. I cleaned off that run of wire with the MAF cleaner that I had, covered those wires in the high-temp liquid electrical tape, and then covered that in high-temp electrical tape. Not a proper fix, but it was the best I could do for the time being.

I am happy to say that it has now been a few weeks without a single code, including driving in the rain, so I'm guessing that short against the engine for the ESS wiring was truly the issue.

It was definitely a tricky one since it was so sporadic for me, but hopefully, this can help somebody else fix theirs faster than 2 years.

klatt

It took me a while, but I got there!

TeamRX8

iTrader: (25)

my apology for having given you the noob treatment back then.

Have to respect you finally digging into it correctly and resolving the issue, and also coming back to detail the fix. Hats off to you. 🙇‍♂️
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klatt

Ha, no worries man, but thanks for the hats off, I appreciate it! We're going to be moving again and the wife agreed that the new house shall have at least 1 garage. Wrenching in the driveway in the middle of a NJ winter is not fun.

Rock10

Where are the pics and diagrams?
Thanks