Vibration in MPS6 clutch pedal ?

SO I have the following perfermance mods;

cat back, Standback PnP & Front mount

After running on my "everyday" tune which is set at 13psi I decided to run my 18psi which is usually running most of the time anyway. I gave it a hit and after boosting 15psi the motor would splatter like it was getting fuel or boost cut (sorry dnt know the diiference) hopefully you get the drift. Stoppping at a set of lights I notice my clutch pedal has a vibration when I begin to engage (at the top end approx 20mm or so.

Now I've read that this could be rods but also heard it could be flywheel.
What is everyones thoughts/experiences.

I could run the laptop through it to do a recording to boost it but don't want a rod going through the block.

JVICAMPS6 - I really think you are talking about two separate issues. I have a slight vibration in the top feel of the clutch pedal. Never worried about it. Unless it is severe, I doubt it is a major issue like block internals, more like precession of the throw-out bearing.

I also have an occasional issue with a sharp cut when on boost from low engine speeds and when lifting off throttle for shifts or when progress is balked. It's better managed by keeping rpm up and running the boost off gradually by gentle throttle lift before shifting. I haven't fully resolved it yet. It doesn't occur when in full cry, when the engine is handling all the boosted air, and is generally worse in traffic light situations. I'll be interested to discuss this more with in case we have a common issue. Mine only started when I fitted the FMIC. I think the long plumbing runs are part of the issue.

As an aside, I do think that 18psi is a bit much. It certainly seems to be a maximum for this turbo. More than this and you generate more heat than usefulness. I run a max of 17.5, but have my SB staged up to it.

I also have a slight vibe at the top of the clutch. (noticeably if you happen to rest your foot on the pedal while sitting at the lights) Vibe disappears well befoer the friction point is reached, so I'm not too concerned.

Thanks for that.

It may be two different issues, it just occured at the same time hence I would assume it's related
The vibration is very noticeable at engagement hence the concern.
With the boost cut or what ever it is after the 15psi, well its the first time thats happened and I should note that I tried boosting it a few more times that night and it won't go past 15psi. Its not just a sharp cut, its constant like running out of fuel bunny hopping,, doesn't wanna go anymore.

Its always been going smoothly to 18psi with no problem.

Hmmm - I see. I need to think about that for a while. Have you tried a change of tune for the SB? And did it only commence when you fitted the FMIC or did you have it before?
MPS Garage have the same setup as us, so might have something to say about it too.

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Originally Posted by Jvicamps6

Thanks for that.

It may be two different issues, it just occured at the same time hence I would assume it's related
The vibration is very noticeable at engagement hence the concern.
With the boost cut or what ever it is after the 15psi, well its the first time thats happened and I should note that I tried boosting it a few more times that night and it won't go past 15psi. Its not just a sharp cut, its constant like running out of fuel bunny hopping,, doesn't wanna go anymore.

Its always been going smoothly to 18psi with no problem.

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you need to get some logs. You may be having an issue with your fuel pump, you'll want to keep an eye on the fuel rail pressure as boost comes up.

Does it splutter when still on boost or when lifting off? If the former, then it seems more likely to be fuel cut rather than boost cut, as SC suggests.

Yea I spoke to MPSGarage and they advised that the vibration could be the flywheel and they acknowledge it could also be rods. They couldn't advise on the boost issue. I guess the only way is to take logs as suggested.

Yea it splatters on boost and wont go past 15psi and I dnt hold it.

I have had the set up on for the last yr with the same tunes with no problems.

Bent rod for sure, sorry mate:/ slight bend in the rod transfers thrust to flywheel which is then transfers through the thrust bearing. If its pulsing get it checked, my car was stock when everything turned to shit. I experienced the bunny hopping and no power early days and mazda reflashed and said car was fine.

So can you confirm/test for a bent rod?

See my long post today on http://www.ozmpsclub.com/forum/tech-...tml#post121314 re clutch vibration

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Originally Posted by Jvicamps6

So can you confirm/test for a bent rod?

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Yeah, measure the piston height throw the spark plug hole, remove sump and visually check or put oil preasure gauge and see whats happening

Cheers, So what tool is used to measure the piston through the spark plug hole?

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Originally Posted by Jvicamps6

Cheers, So what tool is used to measure the piston through the spark plug hole?

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make one, out of some thing straight and turn motor with a tool not the starter. Compair spark plugs for fowling

Use a straight brass rod for the probe. Cut the end dead square but keep it a small diameter (about 1-2mm), then gently round it off, but not to a sharp point. It is softer than steel and so won't mark or score anything in the bore. Use a micrometer to measure the OAL differences between cylinders. Make sure your probe is inserted to as to touch the identical location on each piston crown. Set TDC or BDC at zero and note the difference in the full stroke. Take multiple readings in all cases, table and average them. Preferably use a magnetically-mounted micrometer with a suitable probe extension. You can hire them. These engines are easy as the plug holes give good access. Just don't drop any shit down there.

You could also consider getting the car into one of the decent performance shops around to get them to verify it. MRT, Tunehouse, MPSGARAGE would all be able to help you out.

ok thanks, should I be driving the car? I'm not at the moment but to get to these places is it safe to drive?

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Originally Posted by Jvicamps6

ok thanks, should I be driving the car? I'm not at the moment but to get to these places is it safe to drive?

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Down to personal opinion on that one. If you do have a bent rod you are risking pushing it through the crank case... That said if your able to avoid high load you *might* get away with it.

The extremely cautious here will tell you to get it towed to be safe. Others might say just try to avoid boost while you drive it there. Entirely your decision mate, good luck. :2thumb:

If its bend, I wouldnt say its safe.. Id tow it for peace of mind.
It could be nothing.. then again it could be.
Im not a very good gambler LOL