ArchangelX

At least that's what the people at Mazdas & More told me.

I had a CEL light come on yesterday..and I don't fool around with stuff like that. If something happens I want to know why and how immediately.

So I took it to them to have a diagnostic done on it (Took them 3 1/2 hours and I got charged $250 bucks. )

This is what the findings were/are:

Okay...now after talking to these guys, they pretty much said that they suggest a rebuild (planned already) simply because the compression was so low. Next, they suggested that it's possible that it's just a bad temp sensor which would run about 60 bucks plus 68 an hour for labor charge. OR worst case scenario, my ECU is fuxored and working strangely.

They suggested a downpipe would fix my boost problems immediately, but the boost could possibly destroy my engine because of the age and compression problems. They said my turbos are probably pushing only 7psi right now.

On the plus side, they really like the car, and said it was the cleanest and most well kept RX-7 they had seen this whole year. They said it was a definetly nice deal. There was also another black FD that had just finished having some work done on it.

They quoted me $3500 dollars for removal, rebuild, and re-install, plus incidentals.

That's an amazing price for all of that...but it kinda makes me wonder how "decent" the rebuild is. They also had a 20B sitting on the showroom floor on a packing crate, and said it took about 20 grand to install.

Questions:

What do you think of my situation? What would you do?

How much longer do you think my engine will last if I baby it?

And have any of you ever dealt with Mazdas & More? I think they were formally known as Rotary Power.

I'm still planning on going with Jeff and Pineapple racing for the rebuild and work...I was just freaked out by the CEL. Is it safe to still drive my car?

Thanks for the help guys...

By the way..I also got the Sumitomos on..and my god..for cheap winter beater tires, they made a DRASTIC improvement over the bald-*** tires that were on it before. My ride quality is SUBSTANTIALLY improved, quiet, and my car doesn't feel like it's going to fall apart when I hit a bump now. I didn't know tires could have THAT much of an affect on bump absorption.

spurvo

Tires are possibly THE most important part of the suspension, IMO. But then, I'm an idiot..

You are boosting low because you still didn't replace the y-pipe coupling, right? Get one from Mazda or similar source. Your boost will return. And I quote, "... never underestimate how much pressure 10 lbs really is..."

You might try marvel mystery oil/pettit gas additive to help compression. If that don't work, search the ATF treatment.

Did you replace the O2 sensor, or did the problem just go away? Doesn't help a LOT, but makes the engine smoother and more confident. And for $36, why the hell not?

Get a re-test of the thermo sensor when engine warmed to the point the fans come on with the lights on. That's 210F.

GET THE DP!!

End of my useless advice! The rebuild is obviusly in the offing, but wou should be able to baby it through the winter if you make sure you're oil is clean (no MORE carbon buildup) and be kind when you fix the turbo leak

ArchangelX

Okay...my car is completly stock OEM all the way, so no, I don't think that's been done.

The engine bay is pretty immaculate, all the hoses are brand new Mazda OEM from what it looks like. Even the Rat's nest is well taken care of. The original 8 year owner REALLY took great care of this car.

Y-Piple coupling? I'll have to check that out. I've already purchased an HKS DP (I don't need shiny stainless steel on something that's under the car and there's too many opinons about what's the best downpipe anyways).

02 Sensor? Does that have something to do with the CEL light? Ah...so just replace it so that it's getting better readings. A good idea..it's probably shot after 97,000 miles.

I just changed my motor oil and plan on changing it every 1500.

As for the boost...shouldn't I try and keep it the same..will more boost kill my engine due to it's compression problem?

Thanks for the "useless" advice....it's not so useless to me.

13brv3

As for the DP, stainless isn't just for looks, especially on a rotary engine. A mild steel pipe will be rusted and gone looooooong before a stainless one. I've heard some people say 6 months for a mild steel, but I think it would last longer than that. You do have the option of getting it ceramic coated, which will reduce temps even more. There's really no longterm substitute for stainless on rotary exhaust.

For the boost, I would think a lower compression measurement would actually make it LESS likely to blow your engine with extra boost, if the problem is just worn seals. Did they say the compression was even for all sides of the rotors? You could also have cracked seals, which would be an invitation to disaster with more boost. More boost may be sort of a roll of the dice.

Also, you might add the DP, and find that you still have only 7 psi of boost, because that's not really the problem. Do you have a boost gauge?

Good luck,

ArchangelX

It can't be THAT bad.... 6 months is ridiculous.

I don't have a boost gauge just yet, and have yet to do all of the reliability mods. That's on my list of things to do..but the engine has been running for 97k without them, so who knows.

I do have a slight leak in the oil pan...what could that mean?

13brv3

...that you find oil under the car

Nathan Kwok

Leaky oil pan isn't going to affect anything. I would get a boost gauge and verify proper boost. Low compression will hurt your spoolup but you should still see 10psi. In theory a "weaker" engine that has worn seals is more likely to break an apex seal at 10psi than a new one, but its more important to verify that everything is working right before you go ahead and rebuild. You could rebuild and still have a problem with the turbo control system, so I'd fix that first. That way when the new engine goes in if something is wrong you'll know it had to do with the rebuild and not a previously existing problem.

ArchangelX

Welps...they checked out the turbos and they're fine. Both come in at the proper RPM, and they still have plenty of life in them apparently(I think the previous owner drove like a granny). I've got a boost and A/F gauge, but I just need to find time to install them.

They went over the engine pretty decently...they assured my my turbos were great, and were fine, but the boost was just low. They said I was pushing 6 to 7psi of boost on the turbos.

13brv3

Can you expand on that theory a bit. I don't understand how that could be. You may be correct, I just don't understand how.

Thanks,
Rusty

13brv3

Did they give you any more boost numbers, or just "6 to 7"? The official test gives three numbers, ideally 10-8-10. This would be punching the throttle at 3000 rpm in 3rd gear, and watching the boost gauge. You should get 10 psi immediately, then a very brief dip to 8 psi at the 4500 rpm transition, and back to 10 psi immediately. On a stock car, I believe this will fall off to about 8 psi at 7500 rpm. If you never get over 6 to 7, you likely have a turbo control problem. If you get 10-6-6 or something like that, maybe you have a clogged cat.

As for the compression test, did they use a real rotary tester that gives the compression for each face of the rotor? I'm still wondering exactly what a single number of 85 psi means.

Cheers,

Nathan Kwok

A couple of reasons why older engines break seals more easily: After thousands of heat cycles and millions (billions?) of combustions, the metal does eventually fatigue, just like any internal part of an engine, so this weakens the metal itself. As the seals wear down they tend to shift side to side, I don't know the geometry of this but apparently two piece seals don't have this problem. Of course, that can't be good. As the housings wear, if the wear is severe enough, the seals can start to skip across the surface of the housing. So why would 10psi be worse than 7psi? Well, higher combustion pressures means more stress. Some people claim that seals don't wear out, they either break or they don't break, but how it is possible to have any moving part that doesn't wear out first and then break is beyond me. I mean, this is just common sense, where else does the compression go? You rub two pieces of metal together long enough they're going to wear out, and do that long enough one piece is going to break. Of course the compression could also just get so low that the car doesn't run well so it doesn't necessarily get to that point, but if the coolant seals don't go out first, usually the apex seals do.

djantlive

Get a new temp sensor, O2 sensor and DP. That will fix all the check engine light issues. If the engine is meeting the min spec, don't bother wasting money on a rebuild yet. It's probably just boosting lower bc of the old precat.

If the car is due for coolant flush, get that done and do change other fluids are recommended by service inteval.

turbojeff

iTrader: (30)

6 mo for a mild steel DP, LOL....

Try telling that to my old TII with an old school HKS DP, installed in 1988. Still works fine and doesn't have any rust on it.

Used ECUs are cheap, around $150.

$3500 for the motor and R+R. I've seen receipts for around that price, doesn't include any new stuff like hoses, clutch, belts, plugs, wires, injector service, wiring, etc, etc, etc. That small stuff adds up as you might already know.

Oh yeah, DP will probably solve boost issues since they said both turbos are working.

I've heard of engines running at min spec for a while.

Later,
Jeff

spurvo

I'm really sorry. I had you confused with another guy who wrapped his y-pipe connector in electrical tape and a piece of rubber sheet to fix his split. I suck...

If I recall correctly, the loss of compression in these engines is due to carbon building up in the apex seal slots at the top of the rotors. As the carbon builds up (burnt, old oil enemy number one here, followed closely by bad, cheap, 7-11 gas and an old filter), the apex seal is less able to move up and down in it's groove as the rotor turns. Eventually, the seal sticks in the "down" position, or all the way in the seal groove, and no more compression. This can be cleared partially by a cleaning agent that doesn't dissolve/desolvate the oil in the engine (leading to REAL fun friction) but that dissolves the carbon build up and allows it to exit the engine. ATF and MMO both reportedly do this.

Of course, a broken apex seal would do this too, but these more often simply break and wedge into the rotor housing, locking the engine (or scarring the **** out of it!!)

with only 6-7 psi on the primary turbo, are you even having the secondary kick in? Shouldn't unless you make 8 minimally..

The SS DP rusts out in midwest salt road hell after the stupifying heat from the combustion of this engine burns off any hope of protective coating. In WA state, it should last a little longer... but the SS will outlast the mild steel. Why do the job twice?

OK, enough of me making an *** out of me. Boy, do I feel dumb....

13brv3

I'm with you now. Thanks for clearing that up.

Cheers,

ArchangelX

Ah...thanks for the help...this helps alot. I wish I had a mechanical engineering degree..heh.

Anyways...I only talked to the guy at the counter, and he didn't exactly flesh everything out the way I'd like it to be (plus I was waiting for ages, I fell asleep in the waiting room cuz I had been on mid-shift all night).

So I might be making more PSI that he let on. I didn't ask those specific questions you guys suggest, because I didn't know any better. That's one of the reasons I hate dealing with tuning shops, because they don't tell you everything you really need to know. I'd rather find out for myself.

One of the shop owners test drove my car, and after he came back, he briefed me on his ideas of the car. He also said that my secondary turbo was working fine. So like I said..the turbos are great.

They were REALLY pushing and urging me to keep the car stock, and just add an intake and exhaust. They said everyone who's trying to get 350 400 horses out of the stock engine reliably was pretty much wasting their time. Don't quote me on that, but they were really discouraging porting. I asked them if they did porting and they said no.

ATF & MMO? I'll have to do a search on those, because I've never heard of them.

OH..and they were selling an older 1st gen GSL with a brand new spanking engine out in their lot for $995. Is that a good deal? The interior wasn't that great, and the passenger side window didn't work, but it was in acceptable beater condition. Can't beat a new engine..I had him pop the hood of it..and it looked pretty well done as far as I could tell.

Nathan Kwok

I think the shop is giving you good advice and they seem to be giving you the straight story. A lot of times a shop will try and "dumb down" their diagnosis so the customer doesn't freak out with all the technical problems, and they have to assume you don't have a lot of knowledge. If you bounce back some of the stuff you read on the list and kind of give them idea that you want to hear all the gory details then they will probably provide more feedback. They are right that pushing 350-400hp is risky. The forum tends to represent the "bleeding edge" of what is possible with these cars, but the most hassle-free setup is really just a dp and cooling system mods, thats it. Once you start adding more mods it becomes a slippery slope. A lot of guys on the forum track their car and/or drive it extremely hard, in which case you need more mods, but for the average car extra mods add complexity and opportunity to screw something up.

ArchangelX

Ya.

It's kinda sad though...I want to have at least 300 at the wheels. Is that too much to ask?

I'm hoping for a low 12-second car...what's the horsepower need in a 3rd Gen RX-7 to equate to that? Can I do it on the stock engine without porting?

Oh..and Nathan..I bought the Koni Yellows also..what do you think about the ride quality with them?

Right now..the stock shocks are killing me...the ride is VERY uncomfortable on uneven pavement.

djantlive

Why are you even talking about mods when your car has issues and the check engine light is on? Get it fixed asap and deal with mods later. I don't understand...

Nathan Kwok

The Konis at the softest setting are comparable to the touring dampers, imho (the shock dyno disagrees somewhat but I'll listen to my butt before the shock dyno ), so don't expect a softer ride than stock, even at full soft. However, worn out dampers sometimes become "harsh" because they aren't damping properly. When I upgraded I felt like I could turn up the dampers to a stiffer setting without making a big sacrifice to ride quality, its hard to describe, but don't necessarily equate ride "quality" with "soft", the Konis are good dampers. Also new tires tend to help ride quality out as well. As far as 300RWHP goes, the most reliable way (imho) to do that would be intake, dp, catback, IC, and boost controller running 10psi. This should get you at least close if not there. What I would do is fill up with 100octane, dyno it on the stock computer at 8psi, check the fuel ratios, then again at 10psi. This is my personal plan, I don't have a horsepower goal but I want to get as much as I can out of the stock ecu without going over 11.2:1 A/F ratio. Some pretty extensive testing done by Wade has shown the stock ecu is good for pretty much any bolt-on you throw at it (including a midpipe), but you MUST control boost at 10psi. I think most "chipped" ecus run way too rich, hurting power, and getting a standalone poses a whole new set of complexities.

ArchangelX

Dude..take some time to read the posts a little more clearly before you start flippin' out.

The mods are after a comlete rebuild.

Everything I've bought so far has been to alleviate the problems that are prevalent in the car already.

My suspension bushings are worn out, the shocks are old and creaky, the bump stops are in shreds, the brakes are toast, and the rotors are rusted plus have been resurfaced a few times already, and the pre-cat is clogged.

I purchased the following to remedy all of that:

Stopping Power:
G-Stop Steel Braided Brake Lines
Brembo Dimpled & Slotted Rotors
EBC Greenstuff Pads
Brake Caliper Paint

Suspension:
Koni Yellow Sport Shock (adjustable)
Eibach Progressive Springs
Front and Rear Bump Stops
MazdaSpeed Bushings (complete set)
Cusco Front & Rear Strut Bar(I later cancelled the rear strut bar cuz I didn't know I already had one in the car. )

Exhaust:
HKS Downpipe

Gauges:
Boost
A/F with EGT Sensor (I'll be using my GReddy A/F from my Celica)
Temp

Electronics:
Apex-i S-AFC (again..from my Celica)

The car has been running strong for 97k WITHOUT all of the reliability mods....and I'm just gonna wait till the rebuild to do the AST(which the car has a brand new one on it, anyways), FMIC, and Fluidyne Radiator.

I just want the engine to last a few more months so that I have enough cash for the rebuild. I don't plan on racing it...or even pushing it much at all until then.

The CEL light came on AFTER I had a full engine check-up at a Mazda dealership that pointed out all of the problems.

So far..after resetting the CEL light..it hasn't came on again in the two days of driving it for the work being done on it. Hell..I drove it to Sea-Tac Mall tonight from Tacoma..just to test it out. It's driving great, if a little slow cuz of the Pre-Cat problem.

ArchangelX

Thanks Nathan. That sounds like a good plan either way you go...it at least has some creative thinking behind it.

I was originally asking because I'm not sure if I should get a port or not..I want a reliable semi-daily driver that will end up as a garaged vehicle that's only for fun runs after I get a beater. At that time, I'd probably want to up the modifications on it, and make it more trackable than streetable. Get my drift?

How fast does 300WHP equate to in the qtr mile, just outta curiosity?

And with that much power being put down..do you think the car is good for the track? Would it be a good weekend warrior with that much power?