Jazzmeson

iTrader: (5)

Sad for me to say, but it seems like my engine is on its way out. 2005 RX-8 Shinka with 51,000 miles on the original engine is starting to show symptoms of low compression. I'm currently not having any issues starting the car, but there are occasional long cranks taking between three to four seconds before it fires up. Another issue is that I've been having idle problems on start up, especially when the engine is cold.

Mods and Maintenance:

Mazda Upgraded Starter
BHR Ignition
NGK Spark Plugs at 50K
Throttle Body Cleaned
MAF Sensor Cleaned
ESS Sensor Cleaned
Everstart Maxx Battery Replaced at 36K
Castrol GTX 5W-30 Every 3K
Idemitsu Premix 0.5 oz Per Gallon of Gas
ECU Reset and 20 Times Brake Pedal Reset
Recently Replaced Upstream O2 Sensor W/ Bosch OE Style (Original Denso sensor threads were stripped after header install)

Other Mods:

TurboXS Header
BHR Mid-pipe
Borla Cat-back
AEM CAI

One odd situation relating to the idle is that it will hang around 2100 RPM on a cold start and suddenly drop to 1000 - 1100 instead of a gradual and slow drop as it warms up.

Today, I started the car again after letting it sit overnight and after a recent car wash. Idle suddenly dropped again from 2100 to 1100; all of a sudden the car started to rev up to 1500 RPM then down to 1000 and up to 1500 and then 1000, then dropped to 600 and back up to 1000. After I let it warm up, I turned the car off and started the car again and it fired right up, but the idle dropped down to 500 - 600 RPM before it returned to the normal 900 idle.

After that situation, I started the car once more about a half an hour later and the car started perfectly normal again without any RPM fluctuation. Yet.I am sure that the problems will return again very soon.

Experiencing all these symptoms has lead me to conclude that the engine is giving up. With all the preemptive mods and maintenance I've done, there is no other reason for my car to be acting this way aside from neglect from the first owner I'm guessing. Admittedly, my biggest mistake was not getting a compression test during the warranty period which is now expired.

I just felt like sharing my recent experience so far and it seems like the only solution for me is to save up and get a rebuild when the engine completely surrenders. I would greatly appreciate suggestions from you all on what other factors I could possibly look into, otherwise feedback on rebuilds would be great too.

Thanks everyone!

Brettus

iTrader: (2)

I wouldn't be thinking worn out engine unless I knew the compression was down.


* BHR coils need a dwell change to be as good as stock coils on startup. They are worse than stock otherwise.
* Try monitoring your water temperature via the OBD and see if it is stable . If not , that could be the idle fluctuation issue .

Jazzmeson

iTrader: (5)

Ah, I see. I had no idea that the dwell change played an important role on start-up times. I was starting to wonder why I always had consistent start ups on OEM coils.

I'll definitely look into reading the water temperature as well, just need to find myself a an OBDII scanner.

Reading this response makes me want to finally invest on an Accessport!

Chapsy

Not meaning to thread-jack, but what do you mean by "Dwell Change"?

I've been pondering getting a BHR system for my 8 in the future, and it would be handy to know about this if it's crucial to getting the coils working properly.

thanks.

j9fd3s

dwell is the time the points are closed. an ignition system works by charging the coil, and then when the points/transistor opens, the coil fires.

so dwell is the time that the coil is charging, and if you had the thought that the charge time was related to the spark power, you would be 100% correct.

the dwell time is expressed in milliseconds (ms), and the stock Rx8 runs around 2ms.

the GM coil being larger needs more than 2ms of charging time to have the same output as the stock Rx8 coil. so if you want to run the GM coils, you need to change the dwell in the stock map to make it an improvement.

the coil thread - RX7Club.com

Loki

iTrader: (1)

I ran BHR coils for 2 years on stock electronics, no perceptible difference between stock coils, BHR coils at stock dwell, and BHR coils with adjusted dwell (via AccessPort). Don't take this as gospel, but don't let dwell stop you from getting BHR coils. Peace of mind and all that.

tpb7463

iTrader: (1)

I wouldn't conclude anything without a compression test. That's the definitive test.

And I second what Loki mentioned about BHR coils--ran them for a year without a noticeable difference before I finally found a second-hand Accessport.

Fuel pressure (and fuel pump health) is an important metric on this car. A fluctuation in pressure could account for what you're seeing.

Brettus

iTrader: (2)

I accept that these coils on stock dwell can 'do the job' and not cause issues . However , they wont be as strong as stock and if there are other issues they can definitely contribute such that start-up does become difficult. I have confirmed this several times over on different cars.

Jazzmeson

iTrader: (5)

Hey guys, just wanted to give an update on the situation. My car still acted a bit funny for a few weeks with constant idle fluctuations until I tackled down every single factor I could think of; funny thing is they are such simple fixes that I should have looked into already...

My positive battery terminal had tons of corrosion; I used a wire brush and cleaned off CHUNKS of powder.

I found out that one of my spark plug wires weren't fully seated on my BHR kit. I thought I pressed the wire terminals enough before... Until now, I pressed them again and one of them "clicked" into place.

I cleaned the MAF and ESS again and reset my battery and did the ESS profile reset as well.

The last thing I found that was a bit of a bonus is that I had an exhaust leak which was causing a really loud rattlesnake like noise every time I stepped on the gas. It turns out that my gasket between the header and mid-pipe wasn't sealing properly and replacing it with another OEM one fixed the noise.

So much fail I caused from the course of my own actions, Lol.

Results?

A happy running RX-8. :D Idle is really stable and doesn't dip below 800 anymore and cleaning the terminals resulted in really fast starts every single time. (Only takes one to three turns to start most of the time) I bought a Flex Innovations grounding kit as well to help stabilize the electronics and idle a bit more.

Jazzmeson

iTrader: (5)

Alright guys, just wanted to update you all on the situation.

Car has been acting up again the last several weeks. My throttle response was poor after a long highway drive to and from SevenStock which made me assume that it was the fuel pump; I replaced it with a Walbro GSS342 and it improved the response quite a bit, but still didn't fix the hesitation issue.

Now, for the real problem. When going up a hill or trying to maintain a steady speed requiring a bit of load, the car starts hesitating/skipping/shaking around 4000 - 4200 RPM in EVERY gear and you can hear a lot of popping noises in the exhaust that sounds similar to popcorn in a microwave. The car also occasionally stalls at stop lights and it struggles to hold idle every few seconds, then finally stabilizes after several fluctuations.

P.S. No CEL. Car accelerates fine without any hesitation at WOT and has no hot start issues with the upgraded starter. I also don't have a catalytic converter so it's definitely not a clogged cat.

Things I ruled out already:

-Checked for vacuum leaks and couldn't find anything.
-Cleaned the throttle body.
-Cleaned the SSV.
-Cleaned the MAF
-Cleaned the ESS followed by the NVRAM reset and an ECU reset.
-Swapped my BHR ignition back to stock.
-Checked plugs that are about 2000 miles that are light brown and no signs of fouling.
Replaced the fuel pump and cleaned the sock which had no debris in it whatsoever.

Remaining factors to consider:

Bosch upstream O2 sensor may be defective?
Possibly a leaking exhaust manifold/header allowing excessive air causing the O2 to have abrupt readings? (Although, I don't really hear any leaks as far as I can tell)
Fuel resistor?
A faulty or bad MAF giving inaccurate readings?
Agency Power pulley install could be upsetting the ESS?

Next steps being taken:

-Getting a compression test done in a few weeks.

-I'm currently going to find a diagnostics tool that can get some logs of my car soon (Something I should have done in first place along with a compression test).

Any other factors to consider? Thanks guys, much appreciate everything and I hope this thread will help other forum members who may be in the same situation as well.

TRexRampage

Only had my Rx8 for few weeks and I've found that the emmisions on this car suck! Still love the car just a new beast to beat. First thing I did was download the service manual....RotaryHeads.com - Mazda RX-8 PDF Technical Manuals FE3S

I would still get the compression test, but until then use the manual to test components for proper function. Sometimes cleaning isn't enough. There is also a quick diagnosis chart that may help. As far as a OBD scanner, I just got one from harbor frieght that cost me 70 bucks! Worked fine for me even let me do a I/M test before taking it for inspection.

Good luck! The last 20 years with my 2nd gen were fun and agrivating, but I'm still 100% Rx.

tpb7463

iTrader: (1)

Compression. Test. A lot of extra guessing is being done because engine health hasn't been verified.

If the fuel pump improved things, what about cleaning your injectors?

Jazzmeson

iTrader: (5)

Hey thanks for that, I'll definitely check it out and do a bit of reading. I'm not ready to give up on this car yet; hard to find a car that offers so much around the same price range.

Jazzmeson

iTrader: (5)

The fuel pump did improve things, but not significant enough to really consider it as a remedy. Tried using Techron and numerous hard runs and didn't help either. I may consider pulling them out and inspecting, but knowing how clean my filter sock was, I doubt that could be the cause.

I definitely agree though, compression test is definitely the way to go from this point. That's definitely my next step along with diagnostics before taking anymore unnecessary actions.

CrazyJek

Just curious... You don't have a cat, or an accessport. All your sensors and the computer have been reset. How is it you have no CEL? Without the cat your downstream o2 sensor should be tripping am I right? Or am I missing something...

Also...goodluck. My thread is right below yours with my own problem. I just gutted my clogged cat and engine response is much better but my clutch literally just went. Honestly...no luck. I'm bringing mine in for a compression test as soon as that's fixed. I suggest you do the same as a failing engine can and will cause you lots a problems.

Jazzmeson

iTrader: (5)

Well, I used to get a CEL occasionally for my midpipe, but for some reason I haven't gotten one for the past month ever since I reset the battery. From what I know, the rear O2 sensor is inconsistent in throwing a CEL anyway and also has nothing to do with my A/F mixture so I'm not worried about it tripping. I'm worried more about my upstream O2 because I replaced it with a Bosch one along with a header and a several weeks later is when the situation started showing.

Thank you and I read your thread as well hoping for someone to post a solution. I wish you luck as well in your situation! The only hope we both have is a compression test, and unfortunately I have to get rid of my car if I find out that the numbers are low since my car is out of warranty.

Posted From RX8Club.com Android App

nycgps

iTrader: (1)

it does not always trigger a CEL, it sounds weird, but if the sensor doesn't see an "issues" for whatever reason, then ECU will think there isn't any

the rear O2 sensor is not as smart as you think, they just monitor the content in the exhaust stream, or it could be bad and stuck in some "hey, everything is fine" mode, I seen that before in couple of Rx8 I fixed.

GK1707

iTrader: (10)

This is true I've had the Agency power midpipe for almost 10k miles now and no CEL for the cat. It's popped up about twice (when I scraped the exhaust flange on speed bumps) but when I clear it with a handheld scanner doesnt come back.

Jazzmeson

iTrader: (5)

Yeah, the rear O2 is something I also automatically ruled out for that same exact reason. I just find it strange that I still don't have hot start issues and these symptoms only happen around 4,000 and never triggered a light; although, maybe there is a pending code stored waiting to be checked. From what I also remember, a healthy spinning upgraded starter can still mask low compression. (Can someone verify this? I was never absolutely sure, I just remember reading it from a thread somewhere)

nycgps

iTrader: (1)

You can't "mask" a low compression engine with a new starter, if it's bad, it's bad, if it falls below like say, in the low 6 or 5.x range, you still gonna have a hard time starting it. EVEN with a brand new even faster S2 starter.

a Slow starter always make starting an engine harder. it's sad that Mazda raised the compression requirements of 13B-MSP without giving it a faster starter in the first place. I would say this is an engineering oversight.

Jazzmeson

iTrader: (5)

Ah got it, thanks a lot for clearing that up. I have the upgraded starter and I had a recent track day around 3,000 miles ago with the weather at 101 degrees with stock ignition coils. My car always fired right up after turning it off and turning it on around 5 to 10 minutes after a session; it still currently fires up within a second or instantaneously.

So, there is still hope after all. I'll report back again in this thread with compressions results. If everything passes, I'll definitely start looking into electrical/sensors next.

Thank you and to everyone else as well!

j9fd3s

my friends truck, which uses the same sensor, had one go bad, and it didn't stop working, it just got slow. so it ran fine, and the symptom he had was pinging under load, followed by a CEL for system too lean.

we put the laptop on it, and everything looked totally fine, but the long term fuel trim would creep up until the CEL came on.

new AFM fixed everything.

however i would say that while a new AFM/MAF is cheap, i'd see if i could borrow one from someone. basically every Mazda from 2003-now has the same sensor, and a bunch of toyotas too, so you don't need another Rx8 friend.

also Mazda updated the sensor, the old one is a ZL01, and the new one is a L321.

the really dumb part is that they had a bulletin to replace the starter if the car came in with a "hard start" problem, and since all three of my Rx8's had been to dealerships under warranty with a "hard start" complaint, but none of them had the starter i'm going to say its a dealer fail...

the dealership i worked at from 05-08, we replaced as many starters as we possibly could, Mazda payed for it, and we needed the money!

Jazzmeson

iTrader: (5)

Very interesting, thanks for your input. I do remember paimon posting a thread/poll about faulty MAFs; it would definitely help if more people chimed in about getting theirs replaced and fixing their idle/hestitations.

I just looked under the hood and my MAF is ZL01. The sensor has been cleaned numerous times within the last year and half of ownership, so it is definitely possible that it may be on its way out. I've always wanted to see if a new MAF would fix any problems, but I've already spent money on a fuel pump which barely did anything and would rather not spend on anything until I get a proper diagnosis. (Man, would an Accessport be so handy right now, Lol)

I actually like the idea of borrowing a MAF from a different RX-8. I'll probably give that a shot as long as my friends are willing to let me remove it from their RX-8s.

If I may ask, the dealership you worked at, do you recall replacing any faulty MAFs?

j9fd3s

its funny, the same sensor was used on the protege, mazda 3, rx8, etc and we used to replace the protege and 3 sensors all the time (they still stock 3-4 of them), but we rarely (if ever) had to change one on an Rx8.

it may be that ND has some quality improvement in 2002-2003, but the part number didn't change until sometime in 2006 (i think, we could look i'm sure there is a bulletin for the 3)

so since the MAF is pretty easy to borrow, id try that before spending $$

Jazzmeson

iTrader: (5)

Another thing I wanted to add is that since there are a lot more Mazda3s compared to RX-8s, perhaps the failure rate could be higher because of the amount of people who own/drive them everyday compared to our cars. Just a guess or assumption, haha.

I'll definitely borrow a friend's MAF soon and see if it changes. If not, the fight continues until I have time to get a compression test! Thanks for the suggestion again.