whitelight42

I have an '07 6MT with 97,000 miles I bought about 6 weeks ago. A couple weeks after buying it, it started to get hot and humid here. I began to notice the engine losing power after crusing on the highway for 30 mins or so. So hoping that it was something minor I did the following:

Checked spark plugs (like new)
Checked air filter (like new)
Cleaned MAF sensor
Oil looks good

So took it into Mazda today and here are the compression test results:
(All readings are @ 250 rpm)

Front rotor:
7.2 kgf/cm2
7.2 kgf/cm2
7.3 kgf/cm2

Rear rotor:
6.9 kgf/cm2
6.8 kgf/cm2 (failed test)
7.1 kgf/cm2

So it was only barely under the minimum allowance for 1 of 6 readings.
The tech said he recommended a new engine, new coils and wires, and new cat (because the previous owner installed a magnaflow exhaust with what the tech considers a "small" aftermarket cat.)

So I'm wondering if I were to replace the cat, coils and wires, how long would this engine last? What's especially frustrating is that the 8 year warranty expired last Feb. 24...about 4 months ago.

gwilliams6

Here is the RX8 club's compression test chart. We here all wish you had posted here BEFORE you bought your used RX8 so we could have advised you to get that critical compression test before any purchase. I hope you got a great bargain on the car for without any engine warranty left it may cost you as much as the car to get a reman or rebuilt engine. If you do go that route please let folks here know so we can direct you to reputable and relatively affordable rotary engine builders. Going through a dealer will cost you much more. And yes there are certain things you would be wise to also replace in your situation to help a reman engine last. Just let us know what you decide and experienced folks here will jump in with good advice.

A properly built reman can last as long or longer than the original engine if properly installed,broken in and maintained. There are some things to look out for like too much sealant used in remans, leaking into the cooling system and clogging it. RIWWP, one of our moderators has good advice on what to do about that once you have your engine in. Certainly have a complete new ignition installed, coils,plugs and wires. There are good posts on ignition choices in the new owners thread.

https://www.rx8club.com/new-member-f...t-here-202454/

If you need a cat to pass inspections and be legal where you live, there are some choices on that also. But if you can legally go catless that would be best for the longevity of any new engine.

BTW do you know if your compression numbers were normalized for your altitude in relationship to sealevel?

TomX8

How did you feel that it lost power, and when? Once the engine got on operating temp? How much power did you lose? How did it start cold/hot?

I'm mostly asking for myself.

whitelight42

@Gwilliams 6, Thanks for the information. I thought I got a good deal, but apparently not as good (or good at all!) as I thought. Nothing was said about the #s being normalized. The tech did say that if I changed out the cat, coils and wires that the engine could last a year or more. In fact, he told me it would probably last longer if I drove it hard, since high rpms might break up carbon deposits around the side seals, which I'm more than happy to do, except when it has these episodes of power loss. So in that year I could save up for a new motor. What's the ballpark cost of reman?

@Tomx8, I noticed the power loss only after the engine had been running about 4k - 5k rpm in 6th gear on the highway for 20-30 minutes straight. At the worst times it felt like I was running on 100 HP...maybe less, but it starts just fine whether hot or cold.

Colon Terminus

I'm confused. You're running 80-100 Mph. for a half hour and you notice a loss in power. How so? What causes you to think that? Do you have to depress the accelerator further to maintain that 100 Mph. speed? What exactly makes you feel that you're suffering a power loss?

TomX8

I could understand a power loss after it got to operating temperature, but I don't see how it can take effect 20 to 30 minutes later...

Did you atleast try a 0-100km/h (0-60mph)? After a 100 mile drive my car still has its power when I slam the pedal at traffic lights to do my engine a favor and by the feel and sound of it it's still just as happy.

Otherwise try get a date and time with your dealer, for which you can drive 30 minutes on the highway, and drive back once you feel the power loss. Then they can test the compression right away and see if it's really the compression or something else that's messed up.

Does it feel that the power output kind of dies after a certain RPM, or is it over the whole RPM range? If it starts at a certain RPM is could indicate that the exhaust is kind of full of mess, I don't know.

I just know that if the CAT/Exhaust is clogged, it can really mess up your engine. We had a Ford Fiesta from 1990 which barely did 120km/h, and when I came home I saw the CAT glowing of heat. Needless to say, the engine was already damaged by then.

Note that if you run your engine, it will get on operating temperature and stay there. But if you get into higher RPM's, the temp of the CAT can get higher too.
Honestly I don't have much of an idea what I'm talking about exactly, all I'm saying is that you should definitely check the intake and exhaust systems.

whitelight42

When I say it loses power, I mean that when I press the gas pedal, the engine doesn't accelerate even remotely close to how it did before. After the highway driving scenario and while sitting at a light, If I try to take off quickly...I can immediately tell something's different by the lower, deeper exhaust note with an unusual vibrational tone, and the car doesn't accelerate nearly as well across the entire RPM range. I have to press the gas pedal farther into the floor, much much more than normal to get it to go. After it cools off for a few hours, things are back to normal.

gwilliams6

whitelight yes you could have a clogged cat. Not wise to run it hard with any clogged cat. That just backs up more heat into your engine, not good at all. Did your tech remove and inspect the cat to see if it was clogged with the honeycomb material ?

A good reman or rebuilt rotary engine can cost anywhere from a low of $3000 up to 5-6 thousand dollars. It depends on the rebuilder and/or source of the remanufactured engine (reman). It also depends if the core and any other parts from your current engine are still in good enough condition to be used in a rebuild. The RX8club has rebuilders and sources of remans they can recommend and some to warn you away from if you are ready to replace your engine.

You have some issues to figure out if you intend to keep this failing engine for as long as possible. Some have run a good year on an engine with your compression numbers. You may have that clogged cat; a possible vacuum leak; failing coils ,plugs and wires to mention a few possibilities. Is your engine throwing any codes? If I was in your place I would do the obvious and most cost effective, but still most important things first. Replace the coils, plugs and wires and inspect the cat and replace if clogged. That may buy you some time and many more miles with your engine. At your original mileage there are many things that need to be checked and/or find out if they were done by the previous owner or dealer. You can also try to have the engine seafoamed, that might give you back a little compression.

RX8 Club’s recommended maintenance schedule, more comprehensive and proactive than Mazda’s schedule.
30,000 miles:
- Replace Ignition coils
- Replace Plug wires
- Replace Spark plugs
- Clean MAF (mass air flow sensor)
- Clean ESS (e-shaft sensor)
- Reset ESS profile
- Clean power steering connections
- Clean battery terminals and clamps
- Replace transmission fluid
- Replace coolant (Mazda FL-22 is highly recommended)
- Replace air filter
- Replace brake fluid (fluid in the brake lines AND the clutch line)
~$300 USD in parts if you shop smartly.


every 60,000:
...all 30,000, plus...
- Clean all chassis electrical grounding points
- Replace accessory belts
- Clean OMP lines
- Replace rear differential fluid
- Replace thermostat
- Clean / Straighten AC condenser fins
- Clean / Straighten oil cooler fins
- Inspect catalytic converter
- Clean / Inspect intake valving
- Consider / inspect all points in 90,000+ as well, many items fail early
~$130 USD in parts if you shop smartly.

90,000:
...all 30,000, plus any 60,000 not yet done, plus...
- Replace coolant bottle
- Replace radiator hoses
- Replace radiator
- Replace front O2 sensor
- Replace motor mounts
- Inspect clutch pedal assembly for flex / weld breaks
~$900 USD in parts if you shop smartly.
At 100k, anything original in the cooling system is really suspect and failure prone. It represents the biggest threat to your engine.
__________________

whitelight42

The tech did not inspect the internals of the cat, only mentioned how small it is, and after doing some more research, I see what he means...this universal-style Magnaflow cat is tiny compared to the huge stock cat. I looked under the car some more and it looks like a custom weld job where they cut the stock cat section out, and welded in this small magnaflow cat from Autozone (which looks like it fits lots of other makes and models) with extra piping. So just based on its size, its apparent age from the rust on the cat-back pipes, and the symptoms, I'm ready to go ahead and buy a replacement cat or midpipe.

After researching those options, it doesn't look like many companies make high flow cats for this car, and I'm not really interested in a high flow one. I just need a new cat that's not clogged, but I can't seem to find anything but replacement midpipes. So to keep it somewhat cost effective, I'm thinking of going with the Racing Beat dual resonated pipe, even though I would rather have an actual cat and avoid the CEL coming on. Any other recommendations on a replacement cat solution?

I haven't had a CEL come on at all since I've owned the car, and I'm concerned that with that light staring me in the face all the time after the midpipe is installed, it would prevent me from knowing if and when the light should actually be coming on.

The only light that has come on was the coolant level warning light after I got my car back from the dealership, and the tech explained how the sensor in the coolant bottle goes bad, and showed me where to unplug the connection to the sensor. I'll have to keep an eye on the coolant level in the bottle every couple days I suppose.

gwilliams6

You need a good quality cat because of all the heat rotary engines produce. Cheap cats won't last. There are two levels of magnaflow cats. If you go that way again, at least get the better quality one, around $400-$600, NOT the $150 one. A Mazda OEM cat would cost a grand from a dealer, who would probably have to order it. Cats have very expensive materials inside. Yes you need a better cat than the small magnaflow universal one. I put some links below to some RX8 discussion on cats,and some searches for RX8 cats. One of them may be the small magnaflow one you have now, with is NOT good enough.

It would be worth your while to contact Charles at BHR, a RX8club member and trusted merchant and maker of great quality and durable ignition, exhaust and other RX8 upgraded parts.

http://black-halo-racing.myshopify.com/pages/contact-us


https://www.rx8club.com/series-i-tro...verter-222500/


49150 Magnaflow OEM Grade Direct Fit Catalytic Converter (49 State Legal) at Andy's Auto Sport

Catalytic Converter - Magnaflow New York (49150)

Yea the coolant sensors go on these cars. It is only sold with the coolant overflow bottle $125-$150. You can save the money by just checking your coolant overflow level in the bottle frequently. I had the same issue for a year, and finally bought the bottle with sensor from Mazmart (reputable and good oem parts prices).

http://www.mazparts.com/en/rx8-coolant-bottle

whitelight42

Thanks so much for the info...I really appreciate it. I'm going to try to hang on to this car, replace the cat first, and soon after coils and wires and see if that resolves this issue I'm experiencing. It's incredibly fun to drive, and reminds me of a hybrid of my former 2nd gen Rx-7 and '94 Miata...I would hate to let it go so soon.

gwilliams6

You make a huge mistake if you don't replace coils, wires and plugs on your RX8 FIRST with your mileage. Bad coils, wires or plugs can help kill your engine and that new cat. Don't put the cart before the horse. In all your posts you mention coils and wires only. Be sure you replace coils, wires and plugs together.

whitelight42

I checked the plugs and they are like brand new...they look like they were changed shortly before I bought the car. The electrodes are 100% intact with hardly any carbon on them, so after pulling them I put them back in and got a refund on the new ones I had intended to replace them with.

I can replace the coils and wires first, but shouldn't I be more concerned about all the heat that this potentially clogged cat is trapping in my motor, bogging it down? Also, since cats are so expensive, I'm just going to go ahead and get a catless midpipe for now.

Also, I was going to replace the coils with the OEM Type C coils and NGK wires.

Loki

iTrader: (1)

Ideally you want to replace all this stuff before you do any major driving on it. The clean spark plugs aren't doing you any good if the coils aren't generating a spark, and the fuel that goes unburned ends up in your cat, where it cooks off, creating the heat you're worried about. It's all tied together.

Can you see with the previous owner when the coils were changed?

whitelight42

I bought the car from a dealership (not Mazda, btw) so I don't have the previous owner's info, and I'm sure they don't intend to share that with me.

The new coils and wires are ordered and on the way...I'll be ordering the midpipe later this week.

9krpmrx8

iTrader: (46)

Why are you throwing money at parts when you already have compression numbers. You should be saving that money towards a rebuild.

whitelight42

...and if I were to throw all the money at a rebuilt motor, I guess I'm just supposed to break it in on these same old coils and wires, and with a more than likely clogged cat??

9krpmrx8

iTrader: (46)

Well you can't diagnose by guessing, you need to actually test those things to insure they are in fact failing and need to be replaced.

whitelight42

Wish I would've known that the part #s of the coils were carved into the plastic sides of them. I took a flashlight and looked real close at the side of the coil nearest the firewall and it has the part # for the Type C coil already, which came out in 2012. And the wires on my car already have 2013 stamped on them (Sumitomo).

Anyone need a set of brand new OEM Type C coils & new NGK wires??

9krpmrx8

iTrader: (46)

whitelight42

UPDATE:

2 days ago a CEL finally came on: P2096 (Post Catalyst Fuel Trim System Too Lean Bank 1)

Last night, I installed a catless midpipe with new gaskets and new rear oxygen sensor, because I thought the cat was probably clogged and bogging down the motor.

I disconnected the positive battery terminal and left it disconnected over night and after reconnecting it this morning, cleared the VRAM with the 20 brake stomp.

Well, that was a huge waste of money because it didn't help at all! It still drives like it's running way too lean (loud vibrational sound in the exhaust, low on power, struggles to climb hills, doesn't accelerate well).

What I've noticed in the past several days is that it's steadily beginning to run worse even when driving in the cool mornings, whereas it used to only have these symptoms after 30 mins of highway driving when it's hot and humid outside. So now, it runs a bit rough like this in the morning, and like total crap in the afternoons, and I think the catless midpipe actually made it worse.

Any ideas on what else this P2096 code could point to...? as to why it's running lean? Bad front oxygen sensor? Bad fuel pump? Any help is appreciated.

whitelight42

Update: FIXED!!

So after doing more research I decided to take it to the dealer for the MSP16 PCM flash, since the description of the symptoms describe what I was experiencing exactly. Got it back, drove it on the highway and back roads and through town (raced the engine several times), and then back on the highway 40 mins and then 40 minutes back. The engine never tried to stall even once, there was almost no backfiring and I only had minimal power loss going uphill. Some hills I could actually accelerate in 6th gear while going up, and one particular hill that is very long and very steep...I couldnt even climb it at 60mph, but now I climbed it at 90mph. If I drove it like this in this heat for this long before the re-flash, it would have died on me countless times, been backfiring continuously, and no power. I even got it up to 111mph while cruising along in 6th.
So anyone else who lives in hot, humid conditions..if you experience the same symptoms, get the re-flash!
Also, the dealership said "well, it probably won't make any difference since we already diagnosed it and it needs a new motor, but we'll do it anyway." Shows what they know.

UHATEIT

How much was that reflash you got done? Is there any ways of telling whether your car already has it done? I wouldnt mind getting a flash if it would help the car out.

9krpmrx8

iTrader: (46)

whitelight42

I called Mazda North America Operations and they were able to tell me over the phone whether my car had the updated flash or not, using the VIN #.

The flash was $120 plus tax...and I'm happy to say that my 8 is still running great, even in this hot humid August weather in the south.