Difflockcliff

Ok I will have a look to see if I can find one this side.

So I took my car for Diagnostic and all the sensor errors are gone. Yay. But now I get an error (P0172 system too rich continuous). After they cleared the ECU the light went off and stayed off even after a quick drive. However on my way home the light came back on after 10-15min.

The car drives and idles perfectly now except for a flat spot between 1k and 2k rpm in the morning while the engine is cold. Once the car warm up the flatspot is almost gone(stil get a slight flat spot on the random ocasion)

I am not sure what is normal on a rx as this is my first rx I cannot always tell if some things are issues.

Could the flat spot be caused by the O2 sensors acting up?

Thanks RIWWP for all the help :D

Difflockcliff

Glad the car is drivable now

RIWWP

iTrader: (2)

I'm not sure what you mean by a 'flat spot'. No RX-8 I've driven (a couple dozen) has had any driveability between 1,000-2,000rpm. The only time the RPMs sit there is when slipping the clutch to get the car moving off the line, and then briefly until the speed brings the 1st gear rpms above that. In gear with your foot to the floor, the rpms will lag noticeably until about 2,500rpm, where they will start gaining more rapidly, continuing to increase the rate at which they rise until about 4,000rpm, where it will hold that rate to redline. That's a rotary for you.

Normal causal driving should have the RPMs between 3,000 and 5,000, with that shifting farther and farther up the rev range the more spirited you get. Staying below 3,000 for any reason other than idle is a good way to choke the engine to death with carbon. I normally cruised at 4,000rpm, regardless of what speed I was cruising at. The engine is most content sitting there for long periods of time.

Difflockcliff

Basically what happens is the instant I touch the accelerator the revs stutter (the revs dip down to 500 rpm sometimes lower that my battery light goes on due to low revs and then jumps up to 2000 rpm.) this happens no matter how hard you step on the accelerator or how gentle you are. that initial touch of the accelerator makes the revs dip down and with pull away this can be a pain with stop go traffic as your revs are only stable above 2000 rpm and in stop go traffic it makes a person look like a learner driver lol. This is only the case when the car is cold though it sometimes causes the car to stall but not that often. That is why I say I am not sure if this is normal with a rx. If you want I can record a vid of it.

This isnt a major issue as I just have to teach my self to be weary of the dip in the mornings

RIWWP

iTrader: (2)

Ah, ok, so basically that means that the initial gasp of air at throttle tip-in is making the engine run incredibly lean briefly, until the ECU can correct. Since this isn't a common behavior, and the ECU default mapping doesn't have this problem, then this suggests that your fuel trims are currently running you too lean, so that initial gasp of air makes you go so lean that the engine has trouble staying alive.

Since you got a code of "system too rich", this does point at a sensor malfunction. Basically, if the ECU thinks you are too rich, it has probably kept pulling fuel like crazy trying to make you run leaner, and you are running leaner, the ECU just isn't aware of it, still seeing the rich signal.

If I was in your shoes, I'd buy a bluetooth OBD2 adapter, pair it with my smartphone, clear the fuel trims with a battery disconnect, and then fire up the car and let it idle, and watch my short and long term fuel trims to see what they start doing. Also watch my commanded vs actual AFRs, to see what clues I could get about which O2 sensor was the one that the ECU was reporting the 'too rich' off of.

If I couldn't figure it out easily that way, then I'd disconnect the rear O2, reset the fuel trims again, and then repeat. If the fuel trims and AFRs stayed fine, then the rear O2 is the one with the problem, if they still go out of wack, then it's the front O2 sensor.

Difflockcliff

Ok I have tried the obd2 adapter and on bank 1 my short term trim is running on idling at -20 so its super rich. the long term is stable at -5 once i increase my idling to around 2500 rpm the long term trim drops down to around -10 and the short term trim stays at around -20.

if I have a faulty sensor and I disconnect it will I see a difference in the richness?

RIWWP

iTrader: (2)

Remember that BOTH trims are being applied. So -20 short and -5 long means -25%ish fuel is being pulled out. Likely you aren't actually that rich (you could take a whiff of your tail pipe to see if it smells like raw fuel or not), and cracking the throttle open initially is sending you far far too lean, making the engine want to stall.

Disconnect the battery for a minute or so (negative cable), and then fire up the car and let it idle, and watch the trims again. See what they start doing.

Difflockcliff

Ok i tried two things now. I disconnected the battery for around 2 min then reconnected it. I ran obd diagnostic and now my long term trims stay on 0 and short term trim is far below -20. I idled the car a bit and then took it for a test drive while running the app. While cruising normally (around 80-120kph) the short term trim moves to 0 and stays stable there. Long term trim stays on 0 regardless of idle or cruising. Same response when I push the car to 200kph. I then brought the car back removed the rear o2 sensor and disconnected the battery for 2min and did the process again. The results are identical to when I had the sensor in.

Does that mean that the sensor is not functioning at all?

RIWWP

iTrader: (2)

The fuel trims will go to zero when driving in quite a few circumstances, it's normal.

So disconnecting the rear O2 sensor still has -20 STFT while at idle?

I looked back, and you have cleaned the MAF, so yeah, I'd guess that your front O2 sensor is failing badly.

Difflockcliff

Thanks for all the help for the newbie lol I will have a look at the 02 sensors. see if I can test both and if I get some funds together replacing one or the other.

Once i get this done I will give you an update whether it gets sorted

Difflockcliff

Hi Guys. I have been busy! I had a mini cat installed, That fixed my stuttering issue at high RPMs however the trims would still have MAJOR changes to the trims so I still had the erratic idling after a weeks driving. So I removed the front O2 sensor however on the OBD diagnostic it shows the trims staying 100% in the middle without any change. But after driving a full month the car did not get the erratic idling issue at all, but the accelerator stutter was back. But removing the front sensor seemed to have fixed my main issue however fuel economy was really bad.

I bit the bullet and got 2 new O2 sensors but now after installing them they give me errors. I have done a reset on the obd and all possible manual resets including battery disconnect and the brake pedal trick.

the spares shop told me these were original sensors for the RX8 however the connection plugs weren't the same so I had to join the old plugs to the new sensors but the sensors looked identical too my old ones and the color of the wires were the same as well.

I have tested the sensors using the blow torch technique and I get a reading of 89 on both, and all wires are def connected properly so its not a wiring issue. The sensors look like the front sensor so they "seem" to be the correct sensors.

Any help will be appreciated. See diognostic below

ShowHBK

I would check the part numbers to make sure you have the correct O2 sensors for your 8. My 02 sensor just died recently and I got myself the incorrect one and it make the car run VERY rich because it lacked the proper data to idle correctly. Ended up taking it to a family mechanic who fixed it right up.

Check out this thread for more info about the parts and make sure they match up correctly. also, I know this sounds silly but the up and down stream are two different sensors. I know the prices are different for each so make 100% sure you have the correct parts in the correct places.

https://www.rx8club.com/series-i-tro...r-same-244222/

Locker_09

Hi guys. Just wanted to get some insight before i take the car to the dealer.. So the problem is when i come to a stop and the ac is on, the idles plays around 750-1k. i turned off my AC and idle just sit on around between 750 and 1k. i tried this on a few times just to see if it really does it only when ac is on. It never stall but just the idle. Car has BHR ignition coil and new plugs replaced a year ago. 22k miles on the car, I only use 91octane gas, and air filter is also new. it does this cold or hot weather. Also no engine codes.

Locker_09

So after more searching, i didn't kow there is a TSB for the engine mount. Most of my symptoms are similar with other people having bad engine mount issue.

ShowHBK

I'm trying to understand your post...

"when i come to a stop and the ac is on, the idles plays around 750-1k."
"i turned off my AC and idle just sit on around between 750 and 1k."

These two statements are the same, just one is without the AC on. I don't understand your problem or if there even is a problem based on this. Please clarify.

MomMazda15

Once I start it in the A.M. (MO weather) rmps go up to 2-1 in between. After it reaches operating temp. It starts dropping past 1rmps and jumping back up causing to run rich. Engine light is one since 23rd of March. Took to dealership ran test codes came back saying compression ok 6point test ok but secondary intake air pump needed replacement. Dealer said ok for now. As of today my car wants to die every time I stopped and after reaching between 4-5 rmps no More to little acceleration happens so causes me to shift and after reaching highway in 6th gear or any other gear for that matters it studders and feels like a lot of jerking, like it wants to die instead of accelerating. Scares me. Idk what to do so took it back up to mazda and after 9hrs later the expert that "knows rx8s" says he has no idea. And it would cost 3-4 thousand to tear motor out look it over put back in and keep eliminating.... Single parent of 2... Need help!!! My friend and I looked under good til 3am and found a few "vacuums" that might need cap? Also friend said it needs oil intake block... Idk what todo only 67,000miles second engine and salvage title...

Locker_09

the first one goes up and down between those RPM. AC off, it will just sit still.

Salmonella_6

I am having a stalling issue too. Took my car to Mazda and they told me I need a new Intake Control Valve.
If they do it the cost is over $600. Where and what is the Intake Control Valve?

RIWWP

iTrader: (2)

That's a poor diagnosis. There are 4 different intake valves, with different costs. NONE of them will cause you to stall.

Stalling issues at low RPM (like rolling to a stop at a light or stop sign) are typically either an ignition failure or low compression

Stalling at speed when you clutch in and the revs aren't caught is typically a MAF or O2 sensor problem throwing off your fuel trims

'Stalling' where the engine shuts off while driving and in gear is typically a fuel pump failure.

Note I use the word "typically". Exceptions do of course exist.

wcs

iTrader: (2)

What you are seeing with the AC on is most likely the AC compressor turning on and off.

I notice a drop in RPM when the AC turns on then back off.

Some days the AC compressor will cycle quickly and other days it does not.

Locker_09

I know but before it wasn't that big of rpm drop. But anyway a good cleaning on the MAF sensor did the trick. The little bulb looking thingy is covered with dirt. Been a while since i last clean it. After the cleaning, Idle is smooth again even when the AC cycles on and off.

wcs

iTrader: (2)

The little bulb thingy is the IAT (Intake Air Temperature)

Cleaning the ESS is always a good and easy/cheap thing to do.

Glad you got it fixed.

Sed Bogan

My car is dying at idle! Please help. I have replaced coil and park plugs. All of a sudden car does if gas petal not be ping pushed

Salmonella_6

Lopk into changing EGR soleniods behind upper intake manifold. I was informed that the soleniods failure can cause stalling. My car is doing so and it is because of the soleniod.

HotIcedTea

Well, I can join the stalling club, and maybe give a little insight about my problem, which might help someone else.

Ive had a stalling problem for about a year now. It started right before I got the engine rebuilt last summer. Whenever I am going highway speeds (50mph+) and push the clutch in, or put it in neutral, The rpms drop, and don't recover. the engine just stalls out. If I'm going any slower than about 50mph, the rpms jump between 500-1500 (while slowing down) until I get to about 18-20mph, and then it evens out and idles smoothly at about 800rpm.

This issue just started randomly one day as I was driving. I can't think of anything that I did to cause it, although a bit of time has passed since it started.

2004, manual, 101k miles, greddy turbo, accessport

I have rerplaced:
-SSV
-SSV solenoid
-Neutral safety switch
-MAF
-Baro sensor
-Throttle body
-Coils (BHR)
-Plugs
-Wires
-ESS
-Clutch Switch
-Engine rebuilt less than 2k miles ago with goopy seals
-Looked high and low for vacuum leaks
-Started to replace front o2 sensor, but stripped it, and awaiting arrival of extractor socket to remove it

The o2 sensor is pretty much my last hope.
after that all I can think of is:
-battery or grounds
-air and VDI solenoids (no codes though)
-TPS maybe giving some kind of false reading?
-Tune? but doesnt make sense because started happening before the rebuild, and continued the same after

hopefully this will rule out some issues with everyone else experiencing this problem, and maybe someone has some ideas about what could be happening with mine.