Vizard424

iTrader: (1)

Ok I've been searching for a couple of days and I couldn't find anything that resembles what my issues are.

So I just picked up a 2004 turbocharged RX8 that reportedly had the engine replaced around 60,xxx mark. The car currently has 68,xxx. I had the engine compression checked before I bought it and dealer told me the engine was good, but they didn't give me any numbers. I bought the car from an independent car dealer btw.

I've got the COBB AP from Mazdamaniac and only have the very base map but I
believe my issues have been persisting before I installed it. According to the AP my car sits around low 12s AFR at idle, sometimes going up to around 13. Sometimes the AFRs would drop all the way down to 11s. At idle the car sits just below the 1k rpm mark and idles very smoothly. I had check engine light for the O2 sensors and I had both of them replaced, as well as new coils and spark plugs using the RX7 trailing plugs for my leads and maintaining the factory trailing plugs from the RX8.
The O2 sensors I have are from Walker, had a really great deal on them.

I have new wires coming in but they're not installed yet.

When ever I rev really high the car would drop momentarily below idle then ease back into the proper idling speed. But when I'm driving and get on the gas a little bit the car would stall whenever I come to a stop and shift to neutral. I can restart it very easily and it idles fine afterwards. If I am not as aggressive on the gas, when I come to a stop it'll drop a bit below idle (I'll see the lights show up momentarily as if it stalls) then pick back up and go to idle.
If I keep the car in gear and shift to neutral when the rpms drop to around the 1k mark the car idles smoothly.

I was hoping swapping out the coils and plugs would fix this issue but they haven't...would getting new wires fix the issue? I've cleaned out the MAF and reset the ECU properly and that didn't help.

I'm also wondering if I should be running so rich on MM's base tune for turbocharged applications?

Also I was wondering if I had bigger injectors if that would also cause the symptoms that I'm having?
I tried getting to the primary injectors but I'm not sure exactly what I have (I could have sworn I saw red clips so I assumed they're stock) I know for sure that on the P2 and secondary positions I have the factory yellows.

Or it may possibly be a vacuum leak somewhere in the system? I traced out all the vacuum lines associated with the intake portion (the pipes and vacuum fittings from everything between the filter and the throttle body) and those weren't done correctly (but fixing them didn't change the way the car ran).

I also have an aftermarket cat welded in place of the original cat. The downstream O2 sensor was moved to after the cat.

There's also a Turbosmart BOV welded onto the charge pipe going into the throttled body.

Not sure if it has anything to do with my problem but I also have the older GReddy Profex e-01 boost controller installed but it's currently set to off.

Can anyone give any insight or have experienced something like this??
Sorry for the long post...I appreciate any help!

Vizard424

iTrader: (1)

The car drives well as far as I know, but sometimes if I'm in low gear the car rocks as if I'm jamming the gas on and off but only in 1st. I'm not sure if that's an issue because my last car would do that too and it was brand new when I had it.

It doesn't feel sluggish going off the line and seems to pick up speed well enough.

Loki

iTrader: (1)

Well it sounds like a bad tune, but have you contacted MazdaManiac with your logs to get an map specific to your car?
A certain amount of rocking in 1st at low rpm is normal, you have to be very smooth to avoid it.

RIWWP

iTrader: (2)

Sigh.

Yet another owner in the past week or two that has purchased what appears to be someone else's forced induction problem. Although you are better off than the other two at the moment.

A) If you didn't get compression numbers than the dealer was lying to you, or otherwise fabricating a response that they have no way of backing up. A rotary can only be compression tested with a Mazda specific rotary engine compression tester. There are even Mazda dealers that don't have it, so you can bet your bottom dollar that he 2nd hand dealer didn't. If they used an analog tester good enough for piston engines then it's simply not good enough. It will only show the peak value for the highest compression face of each rotor, when you need the highest pressure reading of the lowest pressure face at a bare minimum. Technically you also need to compare each of the 3 faces of a given rotor to each other, and too great of a variance and the engine is technically a failure. A bouncing needle won't give you that.

B) Turbocharged with MM's base T/C map is WAY rich on purpose, it's trying to save your engine. Included in the tuning instructions when you buy the AP is lots of warnings to not go into boost at all until you have started the tuning process.

C) idle drop to near stalling and/or with a stall for an N/A engine could be front O2 sensor, vacuum leak, MAF fouled, intake screens out of place or missing, aftermarket intake, ignition failure (coils, plugs and/or wires), fuel trims out of place, and low compression. Adding a turbo setup to the mix and your issues expand to including tuning issues, airflow issues, improper piping, or just about anything else you can think of. You need to get some clear data logs of the behavior to even have a chance at figuring out what is causing it.

D) It's entirely possible that your O2 sensors are insufficient. If you don't have a proper wideband O2 sensor and/or an actual OEM front O2 sensor you are playing with fire. Other brand O2 sensors have anything from variable output, limited ranges, or improper voltages, and something reading wacky here suddenly and your ECU changes the fueling incorrectly thinking it's correct and boom goes your engine.


E) it's entirely possible that you have engine damage from the prior owner and the prior owner dumped the car as a trade in before getting stuck with the bill.

wcs

iTrader: (2)

Nicely done

Vizard424

iTrader: (1)

I see...I just got the COBB AP from MM but it's refusing to connect to my car (I just had it working long enough for me to flash the ECU with his base map). I'm talking with COBB at Austin atm to work those issues out. As such I haven't even been able to get MM my first datalogs yet. I also wanted to be sure I wasn't having any mechanical problems that he's "tuning" out.

I have the full GReddy turbo kit with the only thing missing is the restrictor plate that's supposed to go in between the upper and lower intake manifolds. But the intake filter is routed into the front bumper. I'm not sure which kit that is but I just recently cleaned it out and re-oiled the filter.

The car has an aftermarket wideband but it fouled out I'm assuming as it only reads 7.53 or 20.3. Does anyone know where I can get a replacement sensor?

Like I said the car idles well...just starts running funny when I start getting aggressive with the gas and I've been keeping boost as low as possible (hitting only as high as 2 psi).

To clarify I had the car taken to a Mazda dealership (the only one in town as I was in El Paso) to have the compression checked and they told me it was good. I believe they had print outs but they were given to the third party dealer as I wasn't the owner of the car. I wasn't too worried at the time because I was in contact with the shop that installed the turbo kit and they said the last time they saw the car was when the previous owner had them put in a new engine almost a year ago. I figured the compression couldn't have degraded that quickly.

Has anyone else on here used Walker O2 sensor? I haven't heard exactly anything bad about them and a buddy mechanic of mine recommended them.

Are there other indicators that I might have a vacuum leak other then the issues I'm experiencing? And how long do MAFs last in this car? With only 68,xxx miles I was hoping most of the sensors and equipment would be in good condition.

Thanks for the replies!!

RIWWP

iTrader: (2)

Sounds like you need to do some research around the modifications that you have to make to a stock GReddy turbo kit to make it viable for the RX-8, and then figure out if the prior owner made those modifications or not. A stock GReddy kit unmodified will turn into a nightmare on an RX-8.



If your wideband O2 isn't reading properly, then that is step number 1. Literally before you even pick up the keys to your car again. Get one in and in get it replaced. Check the Major Horsepower Upgrades section for options, or what other people use.


Aggressive with the gas is not <2psi. Our engine flows so much air that even light throttle can easily start boosting more than that.

Good that the compression test was done at a Mazda dealer. You still should be hunting for those numbers. An N/A RX-8's compression will 'degrade' over time. A boosted RX-8's engine goes from perfect to seal shrapnel in less than a tenth of a second. You can't use length of time since new engine as a determining factor for engine compression on a boosted 8. I'm not saying your engine is blown, I'm saying right now you have nothing other than a smooth idle to tell you that there isn't anything wrong it it, and that still could be lying. I personally wouldn't be able to sleep at night till I had those test results, to the point of getting it tested again myself.


Yes, but not in symptoms that we can just tell you. Depending on where the vacuum leak is, it could cause anything from intake valve flutter, brake boost failure, instable idle, crankcase over pressurization, lean condition, rich condition, or any combination of these plus things I haven't heard about all at the same time, or even changing from one to another over the course of a drive. Vacuum leaks turn the entire tuning process and system into a complete ball of yarn played with by a million kittens stuffed to the gills with catnip.

It's literally not worth trying to solve ANYTHING else until you have fixed a vacuum leak and/or confirmed that you do not actually have one. And since it's not worth the risk to drive anywhere with the car without a working WBO2, order a WBO2 and spend the time while waiting for it to arrive to find that leak. Part of that should be to keep working on how to get an AP connection to the ECU, since there are telltale signs in idle logs of vacuum leaks, namely the STFT being unstable and/or adding fuel unexpectedly.

N/A RX-8s can deal with most vacuum leaks on day-to-day driving without much risk or trouble, just sub-optimal operation. A boosted 8 with a vacuum leak is juggling 6 jars of nitroglycerin. All it takes it a little flaw and one is exploding at your feet.

Vizard424

iTrader: (1)

Thanks!! This is a lot of good information as I've been getting a little lost with the car. First thing I'll source a new wideband sensor. I've been going over the GReddy turbo kit stickies and I've never had an issue with my air pump continually running and since I'm not running the emanage the only modification I should look out for is the correct plumbing of the vacuum source for the wastegate?

Hopefully I can get the COBB AP hooked up and datalogging by this weekend