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 Post subject: Crazy injector AIR LEAK
PostPosted: Thu Aug 13, 2015 5:18 pm 
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Okay, this is a first encounter for me. I recently installed some used 450s, and a week or so later the motor developed some kind of vacuum leak which caused the idle to lope and rev 1.5k for roughly 30 seconds. The air leaked got traced down to the fuel regulator side of the fuel rail. Checked the hoses for the regulator and teed in boost gauge line, were fine, still couldn't find the leak. This is where it gets crazy! I happen to press down on the electrical connector tight on top of the injector near the regulator, and the hiss completely stopped using very little pressure at all. Do these things have seals inside that can rupture? The injector itself is completely seated on both ends, used new o-rings, and the rail is bolted down as specified. I am a bit concerned, since it passes air during vacuum then you can imagine what happens under boost (maybe it seals, who knows).

This isn't something which can be repaired...right?

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PostPosted: Thu Aug 13, 2015 9:42 pm 
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As much as I hate to say, I think bottom seal on the injector got flipped/torn while being installed.

Here is the question.

What brand and size/color are the seals?

I have Felpro and other companies supply seals that are nowhere near the proper diameter and overall inner/outer circumference that they should be.

Start there, because I believe this has to be a simple fix.


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PostPosted: Fri Aug 14, 2015 7:56 am 
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What about the o-ring on the FPR itself where it goes into the rail? Pressing down on the connector could put just enough pressure on that to fix the leak. Just a thought.

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PostPosted: Fri Aug 14, 2015 9:06 am 
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You would have fuel leaking out then .... not air .... correct?

FPR is wet on the rail side of the equation, and dry past the diaphragm (leverage for vacuum operation) to the vacuum line.

Hope I am reading into this correctly.


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PostPosted: Fri Aug 14, 2015 10:18 am 
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Very likely it's the lower O-rings that are leaking. Pretty common problem. You should be able to buy new ones from Mitsu.

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PostPosted: Sat Aug 15, 2015 10:38 am 
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Technically they are rubber insulators, not orings sealing the injector to the head.


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PostPosted: Sat Aug 15, 2015 11:00 am 
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Whatever. You know what I mean ;)

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PostPosted: Sat Aug 15, 2015 11:29 am 
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If that is your guys' guess, I'd like to ponder on it for a moment. If one of those injectors was completely missing its pintle, would that be enough to cause the air leak through the rubber seats going into the manifold?

I have been very reluctant to put that out there, as I do not remember which cylinder this injector got installed......amnesia!

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PostPosted: Sat Aug 15, 2015 2:49 pm 
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Quote:
If that is your guys' guess, I'd like to ponder on it for a moment. If one of those injectors was completely missing its pintle, would that be enough to cause the air leak through the rubber seats going into the manifold?

I have been very reluctant to put that out there, as I do not remember which cylinder this injector got installed......amnesia!
The pintle cap is what keeps the lower portion tightly sealed to the bottom seal, if it was cracked or missing you definitely have a leak.


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PostPosted: Sat Aug 15, 2015 9:02 pm 
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Quote:
The pintle cap is what keeps the lower portion tightly sealed to the bottom seal, if it was cracked or missing you definitely have a leak.

Okay, well....sounds about right then. Only touching the injector clip seals it though, so this ought to be interesting. Maybe I should upgrade the injectors anyway. 560s and a 2g MAF, should be ready to roll without tuning or headaches.

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PostPosted: Sat Aug 15, 2015 11:11 pm 
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Yep, the plastic pintle cap snaps over the metal portion of the bottom of the injector. Without that pintle cap the injector will be very loose in that lower seal and leak. You can buy replacement pintle caps pretty cheap on ebay. I've used the yellow ones before with no issues.

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PostPosted: Sun Aug 16, 2015 8:48 am 
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Doing a proper boost leak test will reveal exactly what is going on. Everything else is just a guess.

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PostPosted: Tue Aug 18, 2015 3:24 pm 
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Yep, the plastic pintle cap snaps over the metal portion of the bottom of the injector. Without that pintle cap the injector will be very loose in that lower seal and leak. You can buy replacement pintle caps pretty cheap on ebay. I've used the yellow ones before with no issues.
Link? This may fix my rough idle.

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PostPosted: Tue Aug 18, 2015 4:03 pm 
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http://www.ebay.com/itm/DSM-4G63-TURBO- ... ee&vxp=mtr


The ones I used were yellow but these seem to be the same thing.

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PostPosted: Sat Aug 22, 2015 8:59 pm 
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Quote:
http://www.ebay.com/itm/DSM-4G63-TURBO- ... ee&vxp=mtr


The ones I used were yellow but these seem to be the same thing.
Thanks for this link. :rock: I'm going to order some tonight.

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