2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

1500rpm shake

Old May 9, 2015 | 04:14 PM
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1500rpm shake

So I put in a new turbo, removed some emissions, and put bigger injectors in. When I got it put back together it was a hotbed for problems (rough idle, no boost etc). Well I've got one last problem. The car shakes whenever it's between 1500-2000rpms. The whole car kind of lightly vibrates. The steering wheel shakes and it's really annoying. What could this be? Sorry if I'm long winded.
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Old May 9, 2015 | 05:16 PM
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If this only happens when in gear and moving, look to the driveshaft u-joints.
If it happens in neutral while sitting still, look at engine/transmission mounts.

If it shakes all the time no matter what, quit feeding it meth.
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Old May 10, 2015 | 06:31 AM
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How are you controlling your bigger injectors? And what "emissions" stuff did you remove?
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Old May 11, 2015 | 12:35 PM
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I removed my Sub zero system, My egr, Air pump, my ACV plus some cylindrical thing on the intake manifold that had a leak. I got rid of my pulsation dampener and put in a new Fuel Pressure Regulator.
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Old May 11, 2015 | 12:36 PM
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it happens whether im in gear or not
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Old May 11, 2015 | 01:25 PM
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roTAR needz fundZ
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Again, you went with bigger injectors, are you running stock ECU? If so thats probably your problem
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Old May 11, 2015 | 09:19 PM
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I'm in the process of installing an s-afc. I installed bigger secondaries. The shaking happens long before the secondaries kick in so that shouldn't matter....and it says the a/f ratios are in the 13's when it happens
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Old May 11, 2015 | 11:38 PM
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roTAR needz fundZ
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But did it do it before you did the list above? Or after? If after than one of the things you did is your cause
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Old May 12, 2015 | 09:17 PM
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after. Could a turbo make the car shake like that? Maybe it's off balanced?
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Old May 13, 2015 | 04:44 AM
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If a turbo were ever that far off, it would grenade itself long before shaking a car... go back and double check everything you did.
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Old May 13, 2015 | 01:41 PM
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Originally Posted by WyomingTII
Well I've got one last problem.
meaning it idles as it should and produces positive pressure now?

The car shakes whenever it's between 1500-2000rpms. The whole car kind of lightly vibrates. The steering wheel shakes and it's really annoying. What could this be? Sorry if I'm long winded.
Clokker mentioned checking the mounts. did you have to move the engine for any reason during this installation? if so, you may want to check and make sure you didn't damage a mount.

also, did this new turbo necessitate a new downpipe, and if so, how close is it to the firewall?
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Old May 13, 2015 | 02:30 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by barkz
go back and double check everything you did.
this one.
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Old May 13, 2015 | 02:34 PM
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One more oddity to add, did you take off or replace the water pump during this procedure? If you replaced it, the pulley boss could be pressed on slightly off causing the vibration. If you didn't replace the water pump but also didn't put the water pump bolts back on in the right order, this will also cause shaking at a specified RPM.
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Old May 14, 2015 | 02:40 AM
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What's the right order for the water pump bolts or whatever your talking about. I only removed the fan. The downpipe isn't any closer to the firewall than stock. How far would I have to move the engine to damage the mounts? I did drop a washer that went into the passenger side mount. I replaced my pressure regulator and removed my pulsation dampener. I removed emissions. There are no vacuum leaks. And I put in a new turbo. Thats it. Also I think the shaft is slipping inside the compressor wheel...how do I fix this? Thanks all
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Old May 14, 2015 | 03:41 PM
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Originally Posted by WyomingTII
How far would I have to move the engine to damage the mounts?
no telling. it depends on what condition they are in to begin with. for example, when i removed the engine from my FC, the passenger side mount literally fell apart.

Also I think the shaft is slipping inside the compressor wheel...how do I fix this?
SAY WHAT???
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Old May 14, 2015 | 07:14 PM
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I meant, how do I fix the compressor wheel being loose on the shaft without getting a new wheel?...... or is that the only way?
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Old May 15, 2015 | 12:58 PM
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the compressor in the turbo i mean
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Old May 16, 2015 | 12:01 AM
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i understood what you said. i was simply drawing attention to it. it needs to be addressed. is it causing the whole engine to shake? i am very doubtful of that, but i'm sure stranger things have happened.

the point is it should be doing that. at best, it can't do it's job. at worst, it will eventually become shrapnel. fix it (or have it fixed) and yes, it would have to come apart.
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Old May 16, 2015 | 02:43 PM
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Well it's not slipping on the shaft. It's still making a low pitched howl, like a police siren.
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Old May 16, 2015 | 03:09 PM
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Originally Posted by WyomingTII
Well it's not slipping on the shaft. It's still making a low pitched howl, like a police siren.
wow. please understand that i'm not trying to be a tool here, but is it slipping on the shaft or isn't it? you need to be absolutely clear on this. was it slipping and stopped or was it not slipping to begin with? if you think there may an issue, it's best to pull everything back apart, check it all out and then start from scratch.

also, you're saying that it's "still" making a howling noise. when did that begin and did it coincide with the shaking you described in your original post? when you asked earlier if the turbo could be the cause, was it making the noise then?
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Old May 16, 2015 | 03:29 PM
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i figured there might be another thread out there.

https://www.rx7club.com/single-turbo.../#post11911304
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Old May 18, 2015 | 09:29 PM
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It's always made noise and shook ever since I out the new turbo in. I doubt they are related though. I don't know if the compressor wheel was ever slipping on the shaft, but it isn't anymore. The shaking and howling are still there but I now know that it's not the compressor wheel slipping on the shaft. What else could the noise be? It doesn't smoke except on start up and that's the motors doing, not the turbos
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Old May 22, 2015 | 12:17 PM
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Check the fan/water pump and make damn sure it's all together correctly. When in doubt, just switch to an E-fan and be done with that stupid clutch fan.
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Old May 23, 2015 | 06:43 PM
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Does this shake happen when revving in neutral or when driving?
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