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This is another post on my new to me 06 Elise with a stage 2 Vision Function SC and my quest to get it right and ready for the driving season. Thus far I have found a host of things wrong such as loose fasteners, SC nosecone clamp bolt missing, alternator lower bolt stripped etc etc. I'm really glad I am going through it, things are getting fixed and I'm getting to know the car well. On my last post I detailed the intercooler bracket repair. "While I'm in there", I thought I should check for boost leaks . So I fashioned an intake plug from a plumbing cap and used a regulator to keep pressure about 12 psi. I removed and plugged the two vent lines to the valve cover and the line to the evap purge valve (more on that later). I applied pressure and like others have stated, there was air escaping from just about every hose and joint possible, some squealing, some hissing. I too was really surprised how tight the T bolt clamps have to be to seal the system. So I was down to just a few leaks now and the one(s) that worried me most seemed to coming from the manifold to head junction. Closer investigation revealed the leaks were coming from the injector bosses. So I pulled the fuel rail and had a look. The injectors are RC 550's and the square cut seals appeared fine but just in case, I subbed a new set in with same result, substantial leaks. I am used to round type injector seals that are tight to the head and injector, these appear to require a bit of squish to achieve a seal. I found the issue to be that the fuel rail spacers are a tad too long so the rail never compresses the injectors into the seals. As there is boss on either end of the spacers, I would need a lathe to accurately undercut the spacer about 1 mm and I don't have one. So what I did is add a small O ring between each injector and the seal. That was all that was needed to seal up the injectors. I think these boost (and vacuum) leaks at the injectors must have been there from day one since the VF install. And I'll bet the car was plagued with hunting idle and other vacuum leak issues.
So lesson learned, a pressure test of the system is an absolute must. I will be adding a boost/vacuum gauge to monitor this important function.

I mentioned capping the vacuum line to the evap solenoid. At first I did not and the pressure eventually overcame the evap diaphragm spring ( I guess) and air blew out the other end. I suggest removing it from the test by blocking the line to it. Luckily no harm done to it, it still holds vacuum fine.
 

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David if you put pressure into the head when the intake valves are closed it puts a lot of pressure on the injector isolators.I would replace the isolators (round rubber seal that goes on engine side of injector). These tend to dry out over time. Also the mating surface on the head must be free of debris as even the smallest piece of dirt will cause a leak. Do not shave the the Bosses! Make sure they are aligned correctly as even when seated the injectors should be able to spin a bit by hand. You can call me. I will post part number for isolators from toyota. Tommy
 

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Yep, I regularly check for boost leaks just like you did except that I remove the timing chain tensioner and unbolt the intake cam to allow the intake valves to close. I'm running the REVX kit and with 24psi, things need to be tight. I've found all kinds of leaks.
 

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Injector isolators
1258569
 

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Thanks for the great input guys. And the Toyota part #s too. I get smarter every day, or least I think I am.
 
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