I'm taking my 97k mile RX8 (2005 GT) in for a precautionary compression check before the core warranty runs out. I fully expect it to pass (no problems), and I'll report my findings. I just tested my vacuum at idle and at 2k rpms. I used the popular Actron $25 gauge plugs in at the VFAD nipple:

Idle: 16-17 in Hg
2k Rpm: 22-23 in Hg

The compression check is on Monday, and like I said, probably will pass just fine.

Service History:
- Oil changed every 2k miles. I used 5w20 until all the Mazda tsb's and the recall came out then switched to 5w30. Mostly dino, sometimes Valvoline Syntec depending on what is cheap at the time.
- Premix starting around 30k miles. Used Lucas UCL, then shortly after been running Idemitsu.
- 50k miles built my own LS2 coil conversion using MSD wires and the *correct* LS2 coil connectors.
- Coolant and brake fluid changed 1x/year.
- Plugs changed every 25k-35k miles.
- Tranny/diff fluids 1x/year with Redline or Eneos.
- I jsut pulled the cat d0wn to have a look and its in perfect shape as far as I can tell. No blockage on the front element. That's with basically 70k of premix.
- Periodic decarbs are done either at plug change or swap in old plugs. Used seafoam or the mazda stuff.

Has good power and running 90% freeway the low fuel light comes on right around 300 miles. Car has good power, and idle is smooth most of the time. Once warmed up it does this little flub/cough/shudder (not quite a misfire, but you know what I mean) that they all do every couple seconds, and that causes the idle to vary by 50 rpms or so. This one just seems to be slightly more pronouced. Plugs have 15k on them and were just cleaned.

That's about it. I'll post back when I have some compression numbers or if anyone has any questions before then.

 

Make sure they note the rpm's the compression was done at.
Good luck, but seems like you'll do fine.

 

keep us posted with what you find out. seems like you really have tried to care for your 8 so it'll be interesting to see the numbers.

 

We're waiting........

 

I'l be sure to get all the info including rpm's. I called around and one dealer wanted $180 for the test...crazy. The test is scheduled for Monday.

One dealer wanted $180 for the test and acted like I nuts to want the precautionary test done...lol. The dealer I went with charges $90 and knew exactly what I wanted.

 

Keep us posted. The outcome sounds promising. Your premix profile is very similar to what I started with when I got the car @ 104k. Used LUCL for 1k and been using Idemitsu ever since (3k). Its promising to hear about how well the cat is doing.

 

We recently had a 2005 auto with 105,xxx miles pass with flying colors. No premix, bone stock.. Sometimes you get lucky..

 

I'm fine with lucky...lol.

But really, besides weekend autox's lately, its 90% highway driven and gets redlined a couple time a day. I usually do a decarb every 10-15k or so, so its stayed pretty clean in there. Actually when I last cleaned off the plugs, they had very little ash/carbon on them. Just a quick spritz of brake cleaner and a quick scrub with a toothbrush and mostly clean.

When I had the plugs out, i peared as best as you can into the housing. The rotor faces looked pretty clean...actually metallic shiney. Last decarb was 10k ago.

So, like you said, got lucky with this one I guess. Its always ran strong and clean.

Glad to hear of another Series 1 passing no problem!

Results coming in the morning!

 

Ok results are in...
Front Rotor:
7.3, 7.4, 7.2 @ 282 rpm
Rear Rotor:
7.7, 7.7, 7.9 @ 276 rpm

Interpolate that over to 250 rpm by looking at the graph and we get:

Front Rotor:
6.9, 7.0, 6.5 @ 250rpm
Rear Rotor:
7.3, 7.3, 7.5 @250rpm

So, front rotor out of spec low and i think the variance may be out. Lemme go dig up the specs.

 

Where did you get your compression test done?

 

I live in Indianapolis now....but it was done at Tom Roush Mazda.

 

Dammit. 5 hour trip not really worth it.

 

Were ya going to offer some support? haha

I've got a copy of the factory service manual and it shows how to interpolate the numbers. I'm thinking the dealer just saw numbers of 6.9 at the higher rpm and thought it was ok. Time to go explain how it works i guess.

 

Just got off the phone with the dealer. They are going to call Mazda NA and give them the compression numbers. So, if they read the graph like we do, looks like its new engine time. The dealer has been very good about hearing me out. I'd say probably the best one here in Indy.

 

I was hoping this place you got the $90 compression test was local to St. Louis, hence your reported location, you deceiver you.

 

Oh sorry! LOL I did buy the car from Bommarito St. Peters....I usually had great service there.

 

Does everyone get the run around on engine replacements?

 

UPDATE:

New engine coming my way under warranty. It should be here in a week and a half or so. The first dealership was being dishonest and obviously didnt want any warranty business....long story there. I took it down to the next dealer, and they were all over it. They did a decarb, and here are the compression numbers post decarb:

F: 6.6, 5.9, 6.6 @ 282
R: 6.9, 7.1, 7.1 @ 287

So very worn out. Before I took the car in to this dealer, I ran it low on fuel and refilled with NO PREMIX. I'm sure that brought the numbers down, and wow could I tell a difference in the way the car ran. It felt pretty gutless and the idle was all over the place. It also sounded really lame.

With premix and a very low compression motor:
1) It never stalled
2) Idle moved around by 50 rpms or so, but was smooth
3) I thought it felt a little whimpy
4) I still got over 300 miles to a tank highway! That is one of the reason i thought I had a good engine still.

So, in other words guys, take your car in for a compression test before the 100k core warranty is up, even if it runs just fine. Dont run any preix in the tank you take it in on. It could be down on compression and you wouldn't know it otherwise if you make a habit of running premix in every tank.

 

Meh, I'm paranoid right now that @ 66k miles I may have relatively low compression on my engine. It's very annoying that there could be little - if any(!) - symptoms.

My suspicion is currently from a weird apparent "misfire" (a sort of hesitation - no flashing CEL observed) on a weekend cruise lately, and afterwards my butt dyno has been telling me things just feel slightly slower in general. I've never had any issues with the engine; no flooding, hard starts, nada. Maybe it's time to take up premixing?

Owning this car since brand new I believe I made some of the newbie mistakes for short periods of time early on, thinking these might have attributed to a lowering of compression; e.g. revving a cold engine to warm it up (to avoid a cold shut down), and not waiting for a proper warm-up before pushing the engine. I am kicking myself right now for not getting one of those personal compression testers. The best I have to go off of at the moment is a dyno number post-ignition tune-up 20k miles ago (182 hp, stock).

Gah, now my mind is all over the place about this again.

 

182 stock is actually slightly above average for a stock 6 port

 

Yea; I've been informally using my dyno numbers to track the approximate "health" of the engine. I was in a good comfort zone then; this month, not so much. I might be plunking down for another dyno run shortly, although I would really prefer to do a compression test. What sucks is that every time I mention getting a compression test done at the dealerships around here, they freak out... then later quote me stupid high prices.

 

Do you have access to one of those vacuum gauges? If so, what is your idle vacuum?

 

So i'm on about 87,000 miles, bought the car with 81k, about 6 months ago. If I go for a compression check and need a new engine under warranty, what will i need to provide them with (paperwork wise) to get the engine replacement?

 

what are the numbers suppose to be at?

also quick of topic question....when i sometimes start/shut my car of it beeps like 3-4 times?.....

im at 85k and im thinking i should go get a test.

thanks

 

No, I do not. Are these vacuum gauges easily accessible (not crazy expensive, available @ local stores)? I've been looking into performing a vacuum test, but am coming up with very little detail on how to exactly perform it. Could anyone possibly point me to a DIY of sorts?