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compression test...oh noooo

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Old 11-02-13, 12:27 PM
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compression test...oh noooo

So I wanted to do a compression test before I installed the new clutch I got...i don't have a rotary compression tester so I just used a regular piston one. I followed the instructions rotary resurrection has on the website... Front rotor hit 30-35 just fine with the valve pressed in but when released it only reached 70-75..the back rotor 30-35 then 95-100....so what this means its blown n needs a rebuild? The car idles fine boost fine and hold the vaccum at 17 when idle... Any insight guy before I pull my hair out lol
Old 11-02-13, 12:46 PM
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It's not great, but it will run fine. Give her hell until it blows. It would save you $5-1000.00 if you were to rebuild it before it blows but just keep having fun until it lets go.
Old 11-02-13, 01:56 PM
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Great. That's just what I wanted to hear:\ this motor has not even 2000 miles on the rebuild (750ish mile break in) tuned in may I was told it was a strong motor, never tracked, always warmed up before wot..... This time I'm gonna rebuild it myself or try to can't get any worse then this
Old 11-02-13, 02:05 PM
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sorry to hear that . But maybe the components were just to old , did you reuse your old housings?
Old 11-02-13, 02:10 PM
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I didn't rebuild it, its a long upsetting story....

I'm very surprised by the results of the compression test. I've Been driving it quite a bit lately and I've been rather impressed. All readings on the gauges seems great even on the apexi power commander.
Old 11-02-13, 02:18 PM
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Did you have the battery on a charger while cranking, did you do the housing with the lower reading 1st or 2nd, floor the accelerator pedal? If it hot starts fine, has even bounces on all 6 with the valve pressed and shows no drive-ability problems at all I would just do as djseven says and drive it.
Old 11-02-13, 02:23 PM
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Battery was on charger, lower housing reading came first, car was up to operatin temp all but. pedal was on the floor it has minor hot start issues, I just thought it was due to heatsoakd coils. But all bounces were even
Old 11-02-13, 02:51 PM
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Could of been a loose fitting. It's odd the front rotor would have less compression. Once I forgot to open throttle and had similar results. Dying batt isn't much help either.
If its starts good while hot it's ok
Old 11-02-13, 02:58 PM
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Haha well I don't have the funds to rebuild it yet either so I'll be driving it for a while longer I hope. I've been working the bugs outta this car since I bought it
Old 11-02-13, 03:25 PM
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What kind of loose fitting would result in low compression?
Old 11-02-13, 05:30 PM
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Ummm yea so I just started my car to run to the store..first time starting it after the low compression test..well the car fired right up but idled like crap and smoked like bitch...like did the compression test pop my motor wtf!
Old 11-02-13, 06:10 PM
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Sure you got the plug wires on good and tight? Didn't somehow hit the vac line for the map sensor?
Old 11-02-13, 06:20 PM
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just dont care.

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the "heatsoaked coils" thing is generally bullshit. i think the rx8 guys started this blasphemy because they were in denial, or one of the vendors just wanted to sell some GM coils to a bunch of people with low compression.
Old 11-02-13, 06:29 PM
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Yes the plug wires are on tight I triple checked everything nothing looks disconnect.. When I started it the smoke filled my garage with the door open, n idle was terrible.. Just lovely... I thought a compression test wouldn't hurt the motor lol
Old 11-02-13, 10:25 PM
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Someone with more experience should know but is it possible the OMP loaded a bunch of oil in the rotors housing during the comp test and its burning it off now smoking and all, or possibly you didn't unhook the right fuel pump cut off relay for doing the test. i haven't done a compression test yet so these are just some ideas.
Old 11-02-13, 10:43 PM
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i followed the steps on banzai racing website..

i dont have a omp, i pulled the egi fuse and ignitior plug, both where a easy reinstall
Old 11-02-13, 11:08 PM
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if the OMP loaded a bunch of oil into the chambers, the compression numbers would have been way higher.
Old 11-02-13, 11:56 PM
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Compression test will not hurt the engine. Something was effected. Very easy to disconnect or break several wires over by the plugs. Especially near the front housing.
Old 11-03-13, 12:00 AM
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I'm going to tear into it tomorrow, i hope i can get it straightened out,
Old 11-03-13, 10:05 AM
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Originally Posted by jacobcartmill
the "heatsoaked coils" thing is generally bullshit. i think the rx8 guys started this blasphemy because they were in denial, or one of the vendors just wanted to sell some GM coils to a bunch of people with low compression.
i guess you have never worked on an RX8, or seen how many coils actually fail on those cars.. i can guarantee you that they are actually as bad as people say and sometimes don't even last 30k miles.

you might even wonder why mazda is on their 4th coil revision.

i'm also not biased since i don't make any kits and i think they are overpriced for a basic bracket, some off the shelf coils and a 10 minute labor-to-produce pnp harness for close to $500.

Last edited by RotaryEvolution; 11-03-13 at 10:10 AM.
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