Is a compression test affected by ignition health?
 

Just called the local dealer and asked about getting a compression test done on my new to me 06 Shinka to get a baseline. Not having any issues, just want to know where I'm at now. They said the test is greatly affected by the ignition system and they won't do a test unless they also do a "zoom zoom" service which sounds like Seafoam and new plugs for some ridiculous price. From my understanding, the ignition and fuel system is bypassed during the test so as not to, you know, start the car. Is this guy full of it? Are there any common service items that affect compression test results?

run away, run away ...

ignition health does affect the compression. we had an 8 come into the dealership running on one rotor, in 2005-2006, and since it ran on one rotor, we compression tested it, and it failed, badly.

we called Mazda, and they told us to put coils and plugs in it. it didn't make much sense, but we did.

so the tech put the new stuff on the car, fired it up, and ran it for a while, re did the compression test and it passed.

i was surprised, i don't think the older engines will behave like this...

the current procedure before replacing an engine is a verified good ignition, or new, and then compression test. if it fails it gets the decarbon; zoom zoom, and then retested. if it still fails, replace engine.

so while new plugs and a zoom zoom cleaning are excessive enough i'd go to another dealership too, it is at least based on something

Is a "decarbon" Seafoam or water injection?

That could make sense. Running with good plugs and coils could have un-fubared whatever trauma that rotor might have undergone running without fire.

That wouldn't apply to Tyler's car, since he says it's running OK. That dealer must be stuck in the process of what to do when someone comes in with a bad engine.

Tyler - zoom-zoom decarbon is some kind of a solvent, like seafoam. I agree with Team - find another dealer.

Ken

Unburnt fuel causes oil film wash...and compression values can decrease.....

BUT...the first post sounds like a money maker to me ;)

Never heard of that service before... :dunno:

There's a TSB on zoom-zoom treatment. You can search for it. :)

Ken

My local dealer said they would not do seafoam (zoom zoom) unless compression results were bad. I get a bad feeling from your dealership. I also agree with run away.

Don't believe 99.4% of the things that Monchie posts.

BC.

Thanks for the info.



Really...i never heard of it. :uhh:

I know, right?
That .6% of the stuff you write is actually on topic, and actually contributes to a thread in a real way. I was just as shocked as you obviously are.

BC.

yes, it should be this way

Found another dealer willing to do it for a very reasonable $105. :) Still not sure if I should do my BHR ignition before or after . . .

Do the BHR after. If it flunks and you need a new engine, it's best to have as little aftermarket stuff as possible.

Ken

Word, that was my thought as well. Don't really think it's having any issues, but better safe than sorry. Quite embarrassed to say I didn't do this before I bought it, but I really have no reason to think there's an issue. Drives very well other than just a bit of vibration at idle sometimes that I'm not sure isn't totally normal. I suspect that's just an ignition issue as it's got 35K on it now and is on the factory ignition parts. It's at the tail end of the 8 years though, might as well be sure . . .

you got owned by monchie :lol:

They must think it affects it because when my motor failed compression they replaced the spark plugs free of charge on mazda.

Maybe you'd care to ask them how the ignition system would effect the test with NO SPARK PLUGS in the engine?! Some dealers really do make me laugh sometimes..... :lol:

Should I have been abusive when I told him to search? :rant:

Ken

Essentially a compression test is not dictated by all by ignition as there is no spark. However poor ignition quality on a RX8 can cause compression numbers to read low over time by buildup. A "decarb" includes spraying Mazdas "zoom power" into the intake ports and reving multiple times to high RPM which as the name states removes carbon buildup from the manifold, shutter valve & rotor housing. I have used both products and I can say seaform is weak in comparison lol

Find another dealer.

It's monchie, so you should of :) :lol2: