Hi Guys,

I was driving home the other day, in a spirited fashion, when I felt a sudden loss of power, then awful idle and sounding like I'm running on one rotor. I got home and checked the code with the Cobb, and sure enough, it's a P0301, Mifire cylinder 1. I check the usual suspects for this, coils (thanks to Charles @BHR for helping me troubleshoot these), replaced the plugs which were pretty dirty. Still no joy, all coils intact, new plugs, and definitely getting fuel. Took it into Mazda, and sure enough, no compression on the front rotor. The kicker? The car has 11000 KM on it since it was replaced LAST YEAR with a Mazda Reman.

Now, the real part of my troubleshooting. What do you guys think could have caused this? For engine related mods, I have an AEM intake, BHR Long-tube Header, COBB tune (DIY with the guidance of Kane), and a Sohn adapter that I've been running Lucas Semi-Synthetic 2-stroke oil (for around 6 months).

Oil consumption seemed to be fairly normal, but I could never really tell if the OMP lines were full of 2-stroke oil or 4-stroke oil because of the discolouration of the lines, they looked like they had a thin line of blue oil going through them, but the lines were so brown/yellowed that I couldn't really tell. So I could have had a slow leak, that disguised the fact that I wasn't getting oil to the seals.

The tune, although DIY, was done using the method taught by Kane's course (calibrate MAF for idle, tune injectors to eliminate trims, then tune to a relatively safe AFR near RBT at 12.2, and also adjust timing at the upper end for better power). Here are the notes I have from the tune.

That timing bit means that from the 6000RPM mark at .69 Calc Load, I increased timing by 1 degree (factorially?) up to 9000 RPM per row. So 6000RPM =+1 degree, 6500RPM =+2 degrees all the way up to 9000RPM =+7 degrees.

The car is run on a minimum of 91 Octane, and driven until warm before opening it up past 4000rpm, always.

So, anyone have any thoughts?

 

What was the compression on the rear rotor?

Unlikely it was the NA tune. Even with crappy gas those parameters shouldn't cause a failure

Was the Sohn using oil?

Failures of Remans are fairly common. still under warranty?

You might be able to see what happened if you tear the motor down. ..

 

Unsure at this time, I didn't ask what the numbers were. In fact, I don't even "know" if it was low compression, the Mazda rep just said it was "gone" on the phone. I'm fairly certain that means low compression in this case, as it was pumping gas out the exhaust and I checked the ignition sources. I'll ask when I hear from him regarding the warranty.

I kinda figured that, just wanted to be sure all the info was out there.

This is my big question mark. I need a way to test/ensure the OMP and adapter are working, without leaking. My understanding of how they work is that the oil is gravity fed to the plate, and that feeds the OMP. The connection for the drive line on the SOHN keys into the drive line for the OMP. I assume that it also keys into something on the engine as well, and that works as the input to the drive line? Is there somewhere I can buy replacement OMP lines with new, untainted plastic to see if the pump works, and just run premix in case it isn't?

The rep said that once I brought in my service records, there should be no problem getting it approved. I did that 2 days ago, so I should hear back soon

I REALLY want to pay the core deposit to keep the engine, but it's a little much to spend on a broken motor, especially with a kid on the way.

 

Well, I got my car back, just doing the break in as per Racing Beat's instruction. It kills me driving under 4K everywhere.

All in all, with a new factory clutch and an oil sending unit, it cost me just shy of $1600 CAD. Not bad, considering the warranty on the parts and service last time the engine was replaced was only 12 months.

Still searching for a method to test the Sohn OMP adapter, as I really want to put it back on, but I also want to verify that it's working correctly before I do. I doubt I'll get another engine covered.

 

A SOHN adapter can't really fail ( I have never seen or heard of one failing on an RX-8 or RX-7). If you install it and it is consuming oil from the reservoir then you know it's working. But for just see what your consumption rate is just to insure that the OMP lines and injectors are working properly as they are the more likely parts to fail.

And what do you mean by oil sending unit?

 

Have you thought about replacing the lines?

 

I wasn't too sure about this one. I thought at the time, maybe it was the OMP, but it was only $145 installed, and I thought the OMP and all that was way more expensive. I'll grab the part number off of the invoice when I get home if you're interested.

And yes, I have thought about replacing the lines, I just haven't really gotten around to it yet.

 

I mean the only sending unit would be the oil pressure sending unit that feeds the oil pressure gauge. But I have never heard of one of those failing and if you paid $145.00 for that you got ripped.

 

Looks like it was that switch, which kinda pisses me off. But then again, I got a new engine outside of the 1 year parts and service warranty for $484.

I'm guessing they got that part for $20 +tax and BS fee, then charged me the hourly shop/diagnostic ($110) rate for it and the install, meaning it totals $145. Sure it's a ripoff for something I probably could have done myself, but I think I'm still coming out ahead on this deal. It does make me a little leery of going back there for minor service.

Where's the best place to buy those OMP lines? Anyone have a link handy?

 

There is an ad that shows up on this site from time to time. They are stainless steel OMP lines by mishimoto. Seems legit, but then again I'm not a scientist.

 

I bought tubing and rebuilt my own using the old banjo fittings.

 

That was pretty expensive....but it is a part worth changing. I know of a couple on Renesis that had failed and cost engines.

I lost one on an MX6 motor myself. $20 part cost an engine.

 

I was reviewing the bill, and I'm not entirely sure where the $145 was from, actually. I paid upfront for the engine and clutch to be done, then it came back and the OSU needed changing and they said I still owed $145. It may have been the service rep just telling me that there was some overage on labour compared to what I paid for everything else. As you said, the switch is invoiced as a $20 part, so it's not like they were hosing me on the price of the part.

I'm inclined to give them a bit of benefit of the doubt, as they did go out of their way to fix a wrong they had every right to ignore, being that they only offer a 1 year, parts and service warranty, and it had been 13 months. Granted, an engine shouldn't fail in 11000 km, but they were out of harms way.

 

Thanks for your input, and I'll definitely take a look, but I do have some concerns.

I'd be a bit worried about stainless steel lines, because you can't see into them. While reading, I have to say that I agree with the opinion of 9k in that the originals typically last the lifetime of an engine, and have the benefit of being clear so you can see inside them to look for trouble.