Eirulisse

Yeah, I've gotten the vacuum smoke tested and it was fine. I changed the plugs myself last time (2-3 weeks ago), and I quadruple checked the leads lol... The only things remaining on the to-do list would be: 1. Replace Fuel Injectors, 2. Get another decarb/cleaning on my valves (SSV and APV), 3. Replace PCM/ECU, 4. Get a good tune.

Could an exhaust header cause any issues? Just food for thought... but it feels like just about any aftermarket header is better than the stock one (I have no idea how Mazda even thought of engineering that stock header, it makes no sense whatsoever... doesn't give the exhaust gasses any flow at all)

UnknownJinX

If anything, replace the engine first. You are delaying the inevitable at this point. Face the reality.

As for the header, the stock header is fine. If you wanna blame the lack the flow on something, blame it on the side exhaust ports. Aftermarket headers aren't as insulated as the stock exhaust manifold, so you could have some heat issues.

NotAPreppie

The greatest exhaust restriction is in the transition from the ports to the log manifold. There's nothing to gain with an individual tube header since the Renesis has no intake/exhaust timing overlap.

See here for a good breakdown on Renesis exhaust header theory:
https://www.rx8club.com/series-i-aft...thread-266914/

The general design of the manifold is fine but you might gain a couple of HP (literally, like 2-3 at 8500+ RPM) by having it transition to 3" earlier.

Eirulisse

Yeah I have a nice manifold now with better flowing tubes than the original; it's way better designed to extract exhaust gasses and collect them to the 3". It does have better throttle response and gives that nice "ghost exhaust" tone at low RPM.

I know I need a rebuild, I'm not denying it, and when the pocket fills up, I'll get it done. I'm just scared that the rebuild won't fix the problem, and I might damage the rebuilt engine if I keep misfiring.

NotAPreppie

That's why you proactively test/replace all the related parts while the engine is out of the car.

scottish

iTrader: (1)

LOL OK I'm wrong says the guy that is trying to internet diagnose via Data logging, by checking AFRs and fuel trims for what reason? to tell you he's loosing spark and or wrong AFRs and bad fuel trims?
we know that already he's told us he has misfires, fuel cut and bad compression which is obviously going to F with the AFRs and fuel trims the PCM is trying to adapt to the underlying problem.

What magical AFR values you know that tells you exactly what component is intermitanly failing you must really know your stuff surprised you haven't got this figured out already.

Dealerships can't even diagnose a component failure if it doesn't chuck a code they go straight to FSMs and start swapping parts no time wasting.

If I busted out scopes, meters and loggers to diagnose my clients issues every time I would loose them faster than I can fix there problems and I would go bust. Its the same equipment every time you get to know the common problems and fixes so you can go straight to replacing parts even if every client describes their unique and very different problem they are experiencing. In the end they are all the same nobodies problem is special.

don't we have thousands of 8s on here with identical fixes but started with a problem they claim to be unique to there car only?
Lots of these Problems and fixes are documented here on this forum but hey your problem has never been seen before ever on here right your the first.

Eirulisse cannot even tell us what is exactly wrong with his car properly because the issues he is describing are totally different each time. He fails to tell us truthfully what he has or has not done to try and eliminate any of the issues he is experiencing.

Yes every engine has blow by, good or bad its unavoidable but to use the term serious blow by to describe good old low compression on a NA motor your looking into this too hard. I really only hear peeps that are running big boost saying this because it is an issue for them. if the blow by was that bad as you are saying then the motor would have some serious starting issues hot or cold and again its not intermittent.

Me personally I would do the following

1 put my stock air box back in. fixed no? Next
2 put my Stock ignition back in. fixed no? Next
3 Put a New stock Oem Fuel pump Assembly back in. Fixed No
4 I Know I have low comp so I live in denial and look for an other problem with it or rebuild time.
5 Screw it take it to the dealer or somebody that knows what they heck they are doing.

Hmmm who knows the person who put the used motor in probably made a complete horses anus of it and totally F'd it up. oh well.

There figured out on a Sunday afternoon done but hey Loki and the rest of you guys are still staring into the Matrix looking for something new to appear.

Only trying to help since you guys have been trying for the past 7 months.

I'm off to try and diagnose an intermittent stall too but only while driving through the mountains of North Carolina only!. thoughts?
Maybe a 7 month long Data Log or just go straight to swapping the barometric sensor.
Hmmm check FSMs and hey what do you know straight to option 2 me thinks.

Anyhoos Now I remember why I stopped logging in to help people.

You guys have this though please post up next year when you figured it out and what was wrong or not as most threads like this do.



Good Luck!

Loki

iTrader: (1)

If throwing parts at clients car is how you stay in business, that's nothing to be proud of. All cars this side of the year 2000 can provide you troubleshooting data, ignoring it seems like a waste of time. If you see an FSM page that describes this particular person's symptoms, feel free to link it.

scottish

iTrader: (1)

You replaced a mesh screen because it was damaged. I've only seen them damaged due to poor installation not by failure. I asked if the Mesh screens where aligned correctly with each other. don't care that you just put a new one in.

You Failed to say you had replaced the coils curtesy of BHR. did you send the whole coil kit including the wire harness to BHR for testing? pointless if you didn't. did you put stock coils and leads back on?

Didn't ask you if you knew how traction control feels or know when it is activated. what I was asking is what state is your tires in? Are they the same brand on all four corners and is tire wear on the four corners pretty close to each other post up. what suspension you are running, corner balanced set up properly stock original worn?

Well sorry to disappoint you but the dw200 and any of the aftermarket pumps that fit into the assembly will out flow the stock pump and thus increasing fuel pressure not more stable at same flow as stock. More flow more pressure more turbulence/ cavitation inside fuel bowl and also causing the pump to overheat. You put it in a unknown condition 63K mileage pump assembly. You do know there is a fuel filter in the pump assembly?
You said you had pressure issues due to what? poor installation didn't hot iron the pop off relief valve enough?
If peeps are going to stuff bigger aftermarket pumps into a stock pump assembly at least make it a New one.
Did you try a stock pump assembly or just assume your DW200 should be good cause its new?

I asked what brand and grade of fuel you use?

Are you tuned? should be for bigger fuel pump and BHR coils.

Don't care for the Data logs unless you are tuned then again still don't care.

Air temp has serious side affects on your tune. if you tuned at 25C the car isn't going to be behaving all that well at huge temp variants either side of initial tune temp.

Elevation also plays havoc with your tune too.

Driving habits your hypochondriac over sensitive rotary butt dyno is feeling a slight hesitation on up shift its probably because you shifted right where an intake valve opens up as you let off the gas. Nothing wrong with this its normal not noticeable when tuned as this is a hugh area in the tune to improve tidy up.

Based on everything else you have said you have done I'm going to say its your whole fuel pump assembly with the DW200 is your issue Im willing to bet my left nut on it.

Replace the fuel pump with a bone stock brand new OEM Mazda pump.

scottish

iTrader: (1)

Didn't say I was a Mechanic nor claim to be one but the technical theory behind diagnosing a problem can be pretty much applied to anything these days.
If you work on the same product day in day out you see the exact same issues day in day out regardless how elaborate the client put a spin on describing there issues. if you can cut through the BS and lies people tell to try and get your full attention then its no different from what the other guy with a so called similar problem. Isn't a club full of Rx8s exactly the same?

Nope your wrong if you have a failing fuel pump the PCM will not chuck a code yes you will see AFRs Change whoop tee do still doesn't tell you its a fuel pump issue. A misfire is a Misfire and AFRs and fuel trims don't tell you exactly where the problem is just that you have issues with your fuel, air,ignition or emissions systems simple unless it chucks a psychical code.

Maybe said person should take the time to read through all FSMs yes all of them to find the relevant FSMs to see maybe which one sounds/looks like the issues he is having plus all the other countless similar threads here instead of thinking he has an issue that is so unique that no one has ever seen before I'm sure mazda have covered everything on this car its called reading between the lines.

We are offering help based on our own experiences you have your way I have mine.

UnknownJinX

Regardless, I feel like this is actually a good approach.

Without replacing the engine, though, I don't think the fixes will solve most of the problems.

Loki

iTrader: (1)

Yes, exactly. So why not start with that instead of "look at these goofs staring into the matrix".

I'm not going to write out the whole diagnosis tree today, but knowing whether his fuel trims are pegged just to maintain stoich at idle, or if his trims are all over the place, or if the airflow reading is super low helps eliminate options that aren't the problem.

I think he's got the right idea, a new engine isn't going to fix any problem that isn't in the engine, could even hurt the new one. May as well learn what we can from this one.

scottish

iTrader: (1)

Errr well I didn't call you goofs you have assumed to call yourself stupid and I said to stare off into the matrix was to say your looking in the wrong place should be looking at the basics. If I remember correctly your the one that said pretty much everything I said was wrong.

Mean while my experience with this similar issue he is having is basically the same common problem that the majority of people on here say is it can't rev to redline. Cut through the Story telling BS!

Do you think a Doctor listens to every word his patient says cause as far as they are concerned they are dying? No he cuts through the BS and lies and goes straight to basics. He doesn't bust out all his medical journals and starts looking for something that he has never seen or heard of before just because the patient says so.

Your the Doctor that has just busted out his journals looking for something new that doesn't excist and he is the patient that says he is taking his meds correctly but isn't.

so cut through his story telling since he can't get his story correct.

In a nutshell 'CANNOT REV TO REDLINE'

Don't care what rpm don't care what time of day or year don't care.

Lets check the easy common and basics first that usually causes can't rev to redline.

Simple Yes No Answers starting from the top.

1 stock tune? Yes/No
2 Is Cat clogged? Yes/No
3 Put stock air box back on? Yes/No
4 Put stock coils and wires back on? Yes/No
5 Put New Stock OEM fuel pump assembly Back on? Yes/No
6 Maf clean? Yes/No
7 ESS Clean? Yes/No
8 SSV free and clear? Yes/No
9 front O2 sensor replaced? Yes/No

Car is back to factory Now and should be fixed regardless of a low compression motor.

There done the basics if he can't answer all of the above in that order then there is no point carrying on.

If he has then you are up now you can start your data logging and looking for you needle in the hay stack.

Good Luck!

Eirulisse

Scottish if u've been reading this thread carefully, like I said, most of the questions u asked are already answered. All basic troubleshooting approaches have been tried and taken care of. Again, if u would have read this thread, u wouldn't even ask if my CAT is clogged because I said I don't HAVE one. Same w/ the MAF cleaning and ESS cleaning. I mentioned above that I replaced my MAF... Also, a failing fuel pump should mean car is running lean, not rich. The problem is, these symptoms are NOT constant. So I cannot label it as "cannot reach red line", because 2/3 of the time I can. I CANNOT blame it on temperature, because it will happen when 20C, it will happen when 30C, or it won't happen at all that day. As for replacing parts back to stock, I'm sorry, but that's not a problem here. I've been running my car w/ the AEM intake for 2 years now, same w/ the BHR kit, and these problems have started only last fall. I also don't need to send BHR my coils for testing if they sent me a completely new and upgraded set... that's just nonsense... I'm not tuned either.

Thank you Loki.... I managed to record a run this morning as I was going on the onramp. It happened after shifting to 2nd, working my way to 3rd and a little bit into 3rd gear. https://www.dropbox.com/s/d3f0j9chzd....csv.xlsx?dl=0

I noticed the read AFR that my app picked up was EXTREMELY low, we're talking low 11's... so something is making it run rich at random times, but cannot figure out what. The fact that it's running rich (if that's what the data log can be interpreted as), also eliminates the problem of fuel injectors not doing their work. A malfunctioning fuel injector should make it run lean, right? So again, based on the logs, if they can be interpreted as running too rich, then spark isn't an issue either.

I'm wondering if it could be the premixing? But I've been premixing for over a year before these issues started. Can't be my air filter, just cleaned that a month or 2 ago....

Loki

iTrader: (1)

I wouldn't worry about premixing, if it's a 1:100 or 1:200 mix, that's not enough to get in the way of combustion.

The fuel trim is not labelled, so it's not clear if its long term or short term. Ideally we need both. Also I'm not sure why it says Fuel trim bank 1 sensor 2, but we need bank 1 sensor 1 (the primary 02 sensor used to set trims). B1S2 is the post-cat sensor, it's not really used for setting fuel trims.

As mentioned earlier, it would be really good to get a few seconds of data from the car idling while warm. What I'm trying to determine is if it's running rich because it thinks you're getting more air than you are, and doing that with a log that includes gear shifts and other things is very difficult. Just a nice steady 5-10 seconds of the car idling at operating temp, nothing else going on.

Also on this run you're operating in open loop (because you're at full throttle) so the commanded AFR and measured AFR go out of sync (commanded AFR is only used during closed-loop operation).

My bet at this point is that if you look at short term and long term fuel trims (for bank 1 sensor 1) on a warm idle, they will be quite high because the car is pulling in extra air somewhere, such as a vacuum leak, and it has learned to apply those fuel trims through the rev range, resulting in overly rich operation. If we find that's not the case, we can explore other options. If it is the case, then the fix is simple, just find the leak

One other thing I didn't think about before is you could do the 20-time brake pedal stomp procedure to clear the eccentric shaft position sensor profile. That can cause misfires (although more consistently than you're experiencing them). Key to "on", car off, mash the brake pedal repeatedly until the oil pressure gauge sweeps on its own. See if that helps.

Eirulisse

yeah, I'm fully aware of the 20-brake-stomp, have done it a few times in the past while trying to diagnose this issue... I can try to replace that to bank 1 sensor 1 (not sure y I didn't do that in the first place, good catch). If u look at the other post I made w/ the dropbox links, the really long log, at the very end, I let the car idle for 5-10 seconds before stopping the log, so u can see that information there, but I can do another one today, give me a few hours.

It definitely looks or feels like it's compensating for something, but not sure what it's doing. What makes it worse is that it's not a consistent problem, like I said, one day it will scream to redline as if it was fresh out of the box, the next it will hate its life and throw at me blinking CELs and/or reach some sort of cutoff not letting me go further. I do have idling issues, more rare though, where the RPMs would be in the proper range, but the car would just not sound happy at all. I "fixed" my idle once or twice by simply hitting redline in 2nd gear when it happened. One of those times it almost sent me to jail LOL... I changed both O2 sensors about a year and a half to 2 years ago, however, from what I've noticed in the app, idle AFR seems fine. Like I said, I'll post just an idle log for u when I get home.

Eirulisse

EDIT: OOPS, I just checked and I DO have the B1S1 enabled in the logging, but it's not picking up any readings. I deleted that column from the spreadsheet cause it had no data, so I made it more user-friendly to read when I uploaded those dropbox links. I deleted a bunch of other columns for sensors I chose to record, but didn't read any values. Either torque doesn't support it for RX8's or the ECU isn't giving torque access to that info.

Loki

iTrader: (1)

That's weird. Torque should definitely be able to read fuel trims. I'm pretty sure I've done that...
Maybe it doesn't like having too many columns or something? :s

I checked the other log, and it shows around 4.7g/sec airflow at idle, but has no fuel trim data. 4.7 is lowish for 850rpm. 14.3 AFR is also a little unusual, it should idle at a perfect 14.7. So it's getting extra fuel somewhere, either via excessive fuel trim (why?) or extra fuel pressure (why wouldn't it have trimmed the duty cycle back to compensate) or a leaky injector. Really curious to see the real fuel trims now.

Eirulisse

Here ya go, this one is literally just idle for like a minute or more:

https://www.dropbox.com/s/c4bn8svyor....csv.xlsx?dl=0

Here's the interesting part... I CANNOT see or record B1S1 trims... Literally (in torque), the sensors u can access for data are green highlighted when car is on and OBD plugged in. The B1S1 Trim isn't highlighted in green. So I'm assuming Torque might have layed it out in Commanded AFR (what the ECU is sending), and Measured AFR? Cause as u can see, there's a discrepancy between the 2 in the logs I provided above. The Actual must be read using the front O2, no? I also found other sensor information, including the Lambda of the front O2.

If 4.7g/sec is low at idle, I wonder what it should be at 6k-7k RPM where I seem to be running extremely rich. It could be an air filter problem then, or MAF still fouling (even though it's new). It's not a Mazda MAF. Still a Denso brand, but not Mazda, so maybe I should try to get a legit Mazda MAF. I'm also wondering if from all the flames I've shot through my exhaust, maybe my front O2 is acting up. And I noticed when I was driving home, that the measured AFR would sometimes go above 14.7, reaching 15, at a stop light and my RPM's would dip a bit below 800, and come back up as the AFR also came back to 14.x... I know rotaries for a fact sometimes dip in RPM and come back up as a normal thing, but idk if it might have anything to do w/ it. It might also be intake temperature, although in the log I just provided u, none of those dips and AFR spikes happened... See? It's extremely hard to diagnose cause it's not consistent at ALL....

BigCajun

iTrader: (1)

Do you still have the stock intake?
It might be worth it to swap it back just to see if it stops.

https://www.rx8club.com/series-i-tro...em-cai-216999/

rx8guy17

So many different answers on this thread, but it really could be an oil control ring going bad. You stated you have low comp numbers so yea maybe the engine does need a rebuild so just enjoy the car until any major problems happen if the seals are getting warned down. If you keep redlining you never know if a bad seal will eventually break and worsen the engine for your rebuild.

Eirulisse

Like I said, I'm well aware that I'm in need of a rebuild. I just don't want this issue to be driven by something else, that's y I'm trying really hard now to figure out what it is exactly, so that when rebuilt engine drops in, it won't do the same thing, potentially damaging the new engine. Today, for example, on my way to work, the baby redlined so fast and easy, it was as if it was fresh from factory.

Cajun, sry, I don't have a stock intake, never did. When I bought the car, it had the Injen warm air intake (yes, u read that right lol), and it also had a dead SSV solenoid. Fixed those about 2 years ago, replaced the SSV solenoid back then and the warm air intake for the cold air intake, and haven't had issues of cutoffs or things of the sort.