Is a compression test affected by ignition health?
#1
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?
#3
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
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
#5
Registered
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.
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
#7
I HATE SPEEDBUMPS!
#9
Yellow looks faster.
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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.
#10
Rockie Mountain Newbie
#11
I HATE SPEEDBUMPS!
#12
Rockie Mountain Newbie
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.
#13
#16
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 . . .
#21
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.
Find another dealer.
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