Stevespeed240

Hey everyone!

I am new to this forum, but not new to Rx8's or Rotaries in general. I have an S1 Rx8 on its second renesis, and I joined the forums after many years of lurking out of desperation.

My car is a dedicated autox / track ca

It features a recently rebuilt Renesis (I installed it but paid a shop in Canada RT Machining to actually rebuild it) a new transmission (twice actually) RacingBrakes front calipers, KW Coilovers, LS Coils, bars, HKS Catback (sounds incredible... when it runs)

And yeah! I love the car even though it gives me undying hell in the reliablity department. I joined the forum cause I am at my whits end with this thing. I have diagnosed everything under the sun (including compression, its at 90psi all rotor faces cold), to fix a Misfire. I think Charles at Black Halo racing is getting sick fo me ordering parts its been going on so long.

But yeah its probably one of my more favorite cars to drive I have ever had, just wish it ran.

200.mph

iTrader: (9)

whats the actual issue? year mileage what trans/engine? has it had issues since the installed rebuild? theres a troubleshooting section but we need a lot more info in order to help

CaymanRotary

why test it cold? Those results are meaningless. You want to test on an engine warmed to operating temperature. Also, are you using a rotary tester? If the car isn't starting, it's likely flooded. Have you tried to deflood it?

Loki

iTrader: (1)

Compression goes down with temperature, so 90psi cold is... less than 90 warm. Unless that's under 200 rpm starter speed, that engine is on its way out. Probably not the cause of misfires, but for a rebuild that's bad. Did they rebuild YOUR engine or did they give you an engine rebuilt with good parts? One of those is a waste of time and money :/

Have you checked the cat?

RX-8 40th Anniversary

how many miles is on that second engine? and are you sure you have diagnosed everything?
anything reused? and is it just not starting orrr..?

Stevespeed240

Its starting and runs okay, but misfires randomly between rotor 1 and rotor 2. I was going to just post in the troubleshooting section, but It appears you have to post here first before you are let out of "are you sure you arnt a bot" prison.

I didnt do the comp test at operating temp cause I am trying to not run the engine as much as possible with it misfiring.

Mileage of the body is about 117k, Mileage on second engine is about 7,500 miles.

I am not sure I diagnosed eveyrthing which is why I came here. I did what I usually do and even had a rotary expert (albiet non renesis expert) come take a look and he still was stumped.

I cleaned the injectors
replaced the coil pack harness
Replaced the coil packs with new Ac Delco D585's
(it has a BHR LS coil conversion on it)
new plugs
new wires
replaced the e-shaft sensor
ohm'd out the ignition wires back to the ECM they are all good
Verified I had spark on all the wires by putting a timing light on them to see the pulses
I did the stomp the brake 20 times with the key in run to clear the NVRAM
Replaced battery terminals
replaced the alternator
cleaned all the grounds on the engine and the body near the engine

Stevespeed240

Also when the engine was rebuilt, we did all new seals all the way around direct from Mazda and or rotary aviation.
New housings, reused the rotors and the irons

Stevespeed240

Quick update,

Replaced the injectors, and the engine wiring harness, cleaned up the grounds (again) and cleaned up the battery terminals, as well as triple checked all the connections to the injectors and the coils,
Runs SLIGHTLY better but still misfiring nearly all the time.

Even tried pulling the "room" fuse which I believe is the fuse to the BCM? That didnt do anything.

I am quickly running out of things to try.

It seems as if the car's timing is just off completely, which with it being 100% computer controlled makes adjusting it very difficult. Does anyone know if the BHR Coils are any different from Standard GM D585 coils (aka Re-dewelled) or something? Cause I even swapped out a new harness Charles sent me and a new set of AC Delco D585 coils maybe thats the issue? I am about to get a new ECM reflashed to the car cause I am out of options.

deldran

I am new to the RX8 world, but I thought I read somewhere that if you are using LS coils you need to change dwell time in the tune. Are you using Mazda edit or versatuner?

MincVinyl

@Stevespeed240 have you checked the knock sensor? Had one of my friends helping me get my engine together and he overtightened it. Good thing I had an extra to take off my other engine. When this issue happened I also had not done the 20 brake stomps and my timing was all off, being catless the car smelled exceedingly rich. In mazdaedit my fuel trims were going +10% to +20% at some times, now fixed to 0.8% and hardly smells. With the code kicking the ecu should also be pulling timing, which in my case was furthering how far off timing was.

90psi on all faces seems incredibly low especially cold. I'd want to see the running temp compression and make sure you aren't seeing single face compression loss due to a side/corner seal. You should be fine to idle the engine up to temp and it'll heat soak while sitting still, which should give a better indication as to what is happening.

You can run the D585 coils on stock dwell with no issues, I did all through college.

Stevespeed240

I am going to check the knock sensor tomorrow morning, I have 3/4ths of another rensis sitting here that I believe has a knock sensor on it I can swap out.

SO MazdaEdit, I have heard of this, but what do you need to use it? (I am going to google it after this), but I tried to get an OFT to work on the rx8 and its like the only mid2000's mazda that isnt supported.

It was a hot comp test, and its not far off from the previous comp test, it was new housings during the rebuild but not new irons (which if I had known really hurt the compression I would have bought as well), but the previous comp test before that was like 95 on all faces 2,000 miles after the rebuild, and I am at MAYBE 7,000 miles on this new engine.
Mazda spec for a rebuild is anywhere between 75-125 with a brand new being 150.

MincVinyl

One test for the knock sensor is to simply unbolt it and zip tie it off somewhere and see if it still detects anything after clearing DTCs. Or just swapping another one and see if the code goes away.

Mazdaedit requires a dongle that is like 200$ or so. I use mazdaedit, but honestly the only reason I went with it over versatune was due to versa having an issue a long time ago with random power losses(fairly certain this was figured out by now if you want to look into it). Mazdaedit feels like a relic of software.

Stevespeed240

I will give that a shot tomorrow! Thanks a million! I’m wondering if I have a damaged D585 coil(s)
the coil harness got sucked into a pulley and sliced up one set of connections, we repaired it (by we I mean my friend Jayce who is premo at repairing electronics) and I just ordered the parts.

I was hoping there was a free version of something that was a hex editor for Mazda out there cause I have access to an OFT, EcuTek, and a Tactrix cable.

wcs

iTrader: (2)

Wow alot to digest here
Plenty of details.
I was leaning towards the injectors not being connected correctly but it sounds like you're sure that's not it.
TBH I would go back to the stock coils just remove any variables while you're trying to figure this out

Do you have a modified intake? A bad Maf can be a real headache.
I just recently experienced misfires caused by a failing fuel pump

Good luck.