I just finished swapping a JDM motor into my 91 N/A MR2. I took it for a test this past weekend. I am having a problem with the stock boost. It will not boost more than 5 psi. I have checked all the piping and vacum hoses, and did not find a leak anywhere. I increased to 12 psi with the boost controller and it will hit it just fine. does anybody know or have experienced this problem. The car runs fine, I have not checked the timing, but there is no hesitation at all. The only thing that I have not changed are the spark plug, distributor cap and rotor. I don't want to raise to boost any higher before I find out what is going with it. Any input would be appreciated.

Thanks.

Not sure what generaton engine you have, but if you did not connect the Turbo VSV you will be stuck in low boost (5-7 psi) unless a boost controller interferes.

It is a second generation JDM. I have a boost controller connected, I thought that when the boost controller is off, it should boost at least 7 psi. I never ran the engine with the TSV. I put everything together and went directly with my old boost controller from my older swap (HKS EZ). It was running 7 psi when it was off on my other engine. I noticed that it spool much faster due to the blitz down pipe. It boosted 12 psi easily when I ran it with the boost controller. I was just wondering why it was not boosting to 7 psi with this swap. The Turbo was fine, it had very little shaft play and no sign of oil leak. Is there anyway to make it run 7 psi without the TSV and the boost controller off, or should I get better boost controller to control low and high boost? I just hate to run it at 12 psi all the time. Could it be that the boost controller filter of the valve is dirty and it is preventing it to at its optimum?

As long as your engine is healthy and yo uare running 92 or higher octane, there is no problem with running 12 psi all day, every day. :D

Realistically, with everything set up right, you should be able to boost to 7 psi. Just to make sure, do you have an accurate boost gauge hooked up?

Is it possible you have a vac/boost leak somewhere?

In that case, 12 psi it is. The enigne has good compression. Did not do a leak down test because don't have the tool. I have an autometer mechanical boost gauge. I have not check to see if there is a leak. Do you know of any good electronic boost gauge and are they accurate if connected to the stock boost sensor?

I'd stick with the mechanical gauge. Not really any reason to use an electrical gauge if the mechanical one works fine.

When you first start the engine, what is it reading on the vacuum portion of the gauge? 20-inHg vac? It should be around there if there aren't any leaks. If there are leaks, it will of course be closer to 0. The engine would also run pretty rough because you would have unmetered air entering the engine at idle.