Topspeed200

I have a 2006 AT RX8 with 100k miles om the original renesis that i've owned for a little less than a year now and the problems are pilling up now. I've replaced plenty of parts, i check my fluid levels everyday, oil changed every 2000miles. coils, plugs, wires, rad, fans, trans cooler, thermostat, andwaterpump all have less then 10k miles.

For the past 2 weeks the car as been constantly flooding and misfiring like crazy. My battery was weak so i replaced that with an optimum red top and the problem went away for a few days, car was back to normal and the feel was great. One night iwent to start it after work, and it cranked and cranked and cranked i gave up and called for a tow truck. After i do the deflood procedure it starts up (after about 10 mins) but the cel flashes and there is 0 throttle response this goes on for about three minutes along with a very rough idle until it finally stalls out and becoms hard to start again. I then do the 20 brake pedal stomp, along with the deflood procedure and the car turns on and idles roughly for about a minute and the cel does not blink or turn on. After this the car runs great as if nothing was ever wrong for a day or two and then back to the same crap!

I need help! I've been reading the forums for a while now and everyone seems to have knowledge about one problem or the other but nowhere have a read the exact same thing. I had the codes read before replacing the battery and they were p0301, p0506, p0506p, p050a

RIWWP

iTrader: (2)

The two problems that exist after starting both sound like they could be either a vacuum leak, a MAF problem, or a front O2 problem.

However, neither would cause problems starting. (but don't rule out that you have 2 or more problems confusing the issue)

Have you gotten a compression test yet?

Topspeed200

Its driving me nuts, is there anyway to test any of these at home? Do these often cause flooding? I got a comression test done about 8 months ago, the mechanic said it was fine but he didnt give me any paper work to go along with it.

Ireally appreciate the reply, thanks alot man.

Topspeed200

i joined the forum today but i've been following it long before i purchased the car. I like to learn the car and i typically do all the work myself with the help of a friend if its needed

RIWWP

iTrader: (2)

"The mechanic said it was fine but no paperwork" is never anything we put any credibility into. It is usually either a cover up for failing compression or a cover up for not actually knowing what they are doing.

Get a proper one scheduled at a dealership and make sure you get paperwork. If the scores are good, that is something rule out plus solid confidence for the near future about the engine. If they aren't, you found your problem.

And yes, a compression problem could cause all of those, though it certainly isn't the only thing that could. You got all of the other basics though, so it's a reasonable next step.

RIWWP

iTrader: (2)

Reagrding doing the work at home, you can vacuum leak test the intake if you are creative and have something to either create smoke or create mild pressure (~5psi), and you use it to pressurize the intake and listen/find leaks.

I don't put much trust in other methods, like spraying carb cleaner around joints. That failed to find a single one of the vacuum leaks i've had over the years.


The front O2 sensor can be tested with OBD2 live data, like through an bluetooth adapter with the Torque app, though it isn't a simple topic to try to just casually impart.

Topspeed200

The mechanic didnt charge me a dime for the compression test, his name was jim over at jpr imports in blackwood nj. Any ideas on what i can use? Im sure icould figure it out on my own but suggestions are always welcome lol. How complicated is the o2 process.

Im sorry for all the questions, you obviously have a wealth of knowledge with rotaries And im just trying to consume as much as i can lol

Topspeed200

Just looked up the obd2 bluetooth and it's relatively cheap. Are there any specific brands that are compatible with the iphone? Im online searching as i wait for your reply.

Honestly just want my car on the road lol i've waited to get an 8 my whole life! �� i have a grand for the bhr ignition system, fuel pump, and starter. But obviously want to figure out if its a compression problem as you suggested.

RIWWP

iTrader: (2)

JPR is pretty reputable and i believe they have a correct compression tester, so you might be fine on that.

My tester is a small air compressor and tank, with a fitting that lets me plug it into a vacuum line to the intake. Then I cap off the intake where the filter is and apply 5psi to the intake track. For my MSM, I test in a couple different ways, capping different parts of the system to test them individually. The RX-8 you can't really. 9k has a custom set up using a party smoke making machine as well to introduce smoke to the intake to make finding it easy enough from smoke coming out of where any leak would be.

For data, you can confirm the presence of a vacuum leak if the short term fuel trim and long term fuel trim combined is +5% or more AND you have a MAF g/s value of under 5g/s. However, this evaluation depends on your MAF and your O2 sensor health being good, and that is an unsure thing at that moment. Still, learning to read OBD2 data and interpret it is valuable, so get an adapter (wifi or bluetooth) and an OBD2 app (Torque is best for Android, unsure for iOS)


For testing the O2 sensors, the first place to start is a Mode6 test. If it fails in there, there is something wrong for sure. Otherwise, it will require 'active' testing in that you will need to watch the behavior while driving and see if you can find any clear problems. Not a simple thing, probably best to start wih some logs and go from there.

04Green

iTrader: (1)

Reading through the list if what you have tried I did not see a "cleaned the MAF" or "cleaned the ESS". No mention of resetting the fuel trims either.

The Congrats thread below has some DIYs for this.

As for and ODB2 reader, I like the ultragauge. I leave it in the car on the mount. It helped me find my vacuum leak in the stupid sight window on my frigging catch can. There is a chance I may not be over that yet.

Topspeed200

Sorry guys i stepped out for a minute. If i used some sort of jar or can with some smoke say maybe from a cigar or charcoal along with some vacuum hoses and the small air compressor the car came with, would that be decent enough to try the smoke method?

Sorry i forgot to mention the cleaning of the maf and throttle body, my mistake. Idid not try resetting fuel trims or ess but i did plan too after reading about it this morning. What problems did the vacuum leak cause in your 8?

RIWWP

iTrader: (2)

Yeah, in theory, you can breath enough cigarette/cigar smoke into a vacuum line into the intake to find it...

Being a non-smoker and all though, I have trouble making that recommendation You would need enough smoke volume to fill in the intake from the air box end of the accordion down to the engine. "A jar" wouldn't work. An incendiary 'smoke bomb' that is often available around the 4th of july could work too, although I don't think i'd want the residue all over everything.


Vacuum leaks can throw off fuel trims, AFR values, etc... The problems are most pronounced at low RPM, but can vary based on where the vacuum leak is and how big it is. A leak in an intake valve actuation line can mess with intake valve openings, for example.

Topspeed200

Its just and idea lol i figured it would be a decent idea, since i am a smoker lol. I was thinking on putting a piece of coal into some sort of fairly large tin can along with paper. Seal it up at the top drill or poke holes for the hoses, seal those with silicone at the entry point and connect one end to the intake and another to the tire air compressor, please stop me if this sounds dumb im just doing some brainstorming.

Ithought about the smoke bomb and the same thing you thought came to my mind lol.

How likely do you think a vacuum leak is? Doesnt look like the previous owner changed any vacuum lines, hoses, or much of anything for that matter.

forgive me for asking, but what exactly does ressetting fuel trims do?

RIWWP

iTrader: (2)

Your symptoms don't really fit a vacuum leak. The main thing that leaves it as an option is that performance improves after resetting the NVRAM. It's still not a good option.


Regarding the fuel trims...
Basically the factory fueling map has pre-set values to cover all RX-8s. These values are stored in a table by RPM and MAF value, so X MAF at Y RPM has a fueling value associated. But every RX-8's MAF is slightly different, the O2 sensors are slightly different. The engine's tolerances are different, etc... So no map is quite right. As the engine runs, the front O2 sensor monitors the oxygen content getting the air to fuel ratio (AFR), and the ECU applies an immediate correction to the fueling map at that location in the form of a Short Term Fuel Trim. If it sees that a given cell keeps getting a similar Short Term Fuel Trim, it will start folding that value at that location into the Long Term Fuel Trim to better optimize the fueling for that RPM and MAF point, and the engine is better optimized, more efficient, and less poluting.

However, this is all assuming that everything is in working order and that the sensor readings can be trusted. A vacuum leak is by definition when the engine is sucking in air that ISN'T passing the MAF, so the MAF is recording too low of a value. The front O2 sensor sees that it's running a bit lean, and keeps adding fuel. Of course, this is still assuming that the MAF and the O2 sensors are working right.

What happens when they aren't?

If the front O2 sensor is failing by having a hard time reading rich values, then the ECU will start adding fuel all over the place since it sees (incorrectly) that you are running line. If it's failing in the opposite direction, the opposite will occur.
If the MAF is fouled (can be common) or failing (rare) then the engine will be using a different amount of air than the MAF says it sees, so the ECU will be in the wrong part of the fueling map, and will start building incorrect trims trying to get everything back into line.

Clearing the fuel trims 'resets' the fueling map to the original factory level, where it is close to ideal anyway. If clearing the fuel trims improves things, then you have a hardware problem somewhere that is letting the ECU build the wrong fuel trims.