Hi yall, here we go. Traci's second post about her RXocho.. I use to think that I was a pretty good wrench, until I inherited this bucket. She is evil, plain and simple. Sitting there in the garage smirkin at me again, stripping me of what little confidence I have left. Sometimes at night, and im outside all cuddled up with my black footed ferret ,sky watching, sometimes I can hear her taunting me..whispering.."you cant fix me, stop trying". Over and over..its maddening.. Ok here is the skinny. I inherited a 2004 rx8 (rxocho) with the 1.3L renesis high power 13B.Was supposed to be a fresh motor install, (right). Maybe I should get right to the issue...
when I got the car it would not idle after warm up. she would just flat fall on her face, but start right back up again until the next stop light. I suspected vac leak, dont remember what codes I was getting, been so long, but whatever it was led me to a 02 sensor. This is how i found out that the wiring harness wasn't original, it had been spliced in , apparently when the motor swap. Kept fighting the code, ended up being they had signal and ground wires crossed.That took care of that code but still wouldnt idle.After several months of scratching my noggin and experimenting, I came to the conclusion that my idle issue was being caused by a faulty fuel pump thingee, umm resistor,,thats the word. Bypassed the resistor and idle fuixed. Yayy me right? pfft I wish...this is where it gets good, I am now getting a p0038, indicating downstream sensor voltage output high. No other codes, car runs ok minus the cel in my face. So, follow me on this plz, and Im wrong PLEASE correct me, its how I learn. The downstream sensor does nothing in terms of vehicle performance, it simply monitors the system. Kinda like a auditor. It sits there and sniffs the exhaust stream, and the more fuel it detects (rich), it converts that into a signal, and outputs this signal as dc volts to the pcm. How am I doin? Not bad for a chic huh? neways, the code p0038 tells us that the output is higher than expected, I think, and because the numbers were so high when I crawled under and took a reading while car was running and warm, I concluded (prolly prematurely) that my system was running rich. So because of the belief that the sensor doesnt effect performance , I experimented.by leaving the 02 nsensor plugged in, but not in the stream. Just wired up and out of the way, plugged the bung,,hahah plugged the bung hole.., reasoning was, no more rich condition translates to no more p0038. Sounded so good on paper, cuz now the rabbit hole is growing again. As soon as I started driving the code came back. WTF? how can I get a fuel rich 02 code, when the sensor itself is breathing all the fresh air it wants?? Moral to the story is...IM STUMPED boys and girls Somebody pweeze take the reigns cuz I am honestly out of ideas and patience.
2004 rx8
no mods
manual trans
13b high power
p0038 heater circuit high
what ive tried, both new sensors, air intake sensor, maf sensor, checked vac leaks check plenium for leaks check exhaust for leaks

 

without looking at a diagram, are the upstream and downstream sensors connected? Could botched wire job on upstream, effect downstream heater circuit?

 

P0038 means there's a wiring problem to the sensor heater, nothing to do with the actual reading. Sometimes when installing engine/trans it's possible to pinch the harness for the rear O2. Solution would be to trace the wire and see if you can repair the damage. Given that the harness was spliced (why..?) maybe that's playing into it too.

Is that the only remaining problem?

 

yes sir, pretty much. Ideas?

 

so the code is thrown when voltage going TO the sensor is too high? Versus my original understanding was that it dealt with voltage LEAVING the sensor on its way to the pcm?>

 

Indeed, remember I was talking about the harness being pieced 2gether? The downstream was butchered, black tape different color wires entirely.. This is how I re-wired it, for all we know its me that messed up the colors. I went blue/yellow for sensor positive white/brown for sensor ground, remaining 2 black wires went to red wht and red for heater circuit. Didnt bother worrying about polarity.

 

By the way Loki..THANK YOU for chimming in

 

Ok so instead of sitting here on my thumbs, maybe ill go take a look at that front sensor wiring. If the downstream was done by a 5 year old, who know what the front looks like. Sound like a plan stan
?

 

Quickie update for anyone interested. ..I flippin hate sayin ,"yayy I got it" cuz everytime i do, another code pops up. But for all intents and purposes Im callin this one licked. And it went something like this. I took Loki's advice and took a closer look at the harness in its entirety. I aint going to fib, that was on my punch list, I kept putting it off cuz I was tired of tearing this thing down.. It got to the point to where I can tear the top off this 13b, blind folded, eating a pbjelly samich and hopping on one foot, in 3 minutes flat. Anyhow, Im sure yall can guess what happens next. For those who do not know, there are 2 grounding points under your plenium!!! Dont be a dumbass like me and over look them. Like i said, Ive had that top off atleast 15 times, and not once did I catch the grounding point with 2 old brittle wires trying to hold on for dear life. And just because Im an obsessive compulsive, I kept going down,... yum..why stop now? Off come the imjectors. Ill be ladylike and bite my tongue, lets say that Ill be paying a visit to said individual who claimed he replaced apex, coolant..seals etc..and lay these injectors on his desk. Ill drop a picture here. So In closing, Thank you for tuning in to the latest episode of... TRACI'S FUKED UP RX8. Final outcome: 2 corroded grounding points, coupled with fuel injectors leaking fuel into the cylinder, causing a rich condition which in turn set off my CEL P0038, this also explains my poopy idle and terrible gas mileage. So did i ace it?? huh huh? Thanks again...stay tuned...cheers

 

You don't have a rich condition. At least the code doesn't indicate it. All it indicates is the sensor heater or wiring to the sensor is damaged, that's all. The "high" in there is not important.

 

Told yall Ide pop back in here when I sorted it., follow this for your solution boys and girls. Alittle late granted, but like my step brother you used to,if at first you dont succeed, keep suckin. Hopefully this helps someone who stumbles across it,This will be 2 part but in all actuality they are prolly one in the same.
1st the dreaded surge. I will absolutly insist that you look for a vaccum leak. Find some ether and start sprayin, pay close attention to valves and solenoids behind intake..ssv etc. Fix the leak fix the surge. Next the stalling at stop light issue.
1st..check the ground that is under your intake plenum,you have 3 ground points, the one I referenced was one of my issues.
2nd..look at your intake air temp sensor, it is combined with your maf sensor on your model.
3rd..look at your fuel pressure, pay close attention to your gas gauge. Our models for some reason dont like to run with anything under 1/4 tank. Irregardless pay attention to your fuel at the rail.
4th..This was my gremlin..look at your fuel injector seals on both the rail and the intake. My spitters were spittin where they shouldnt have been, leaving cute little pools of gasoline in nooks and crannies.
5th..look at your upstream 02 sensor, downstream not so much.
6th. This is one of the things I ruled out first, Look under your air pump, grab that thing that looks like a mini amplifier. That is a fuel pump resistor. My reasoning was that because my bucket would shut off when it got so warm, because resistor would get hot and trip. To verify this I crossed the 2 wire at resistor with no changes. Something to think about.
lastly coolant temp sensor.
In conclusion, I pinky promise I had the exact same problem, now she purrs like a kitten and doesnt even think about stalling at stoplights. Cheers