Hey guys I found something weird today. My boost gauge has periodically been reading 0 at startup when its normally supposed to be a vacuum. I ordered a new gauge..put it in..and it was doing the same thing..i check the line....no vacuum...i went to the engine and pulled off the T-fitting between the intake manifold and the fuel pressure regulator....yet again no vacuum. I pull the line off of the little syllandoid looking thing on the intake manifold...and sure enough there was no vacuum.

I am semi baffled by this....I have been having sporadic engine problems that the dealership couldn;t figure out. I would be acclerating hard and all the sudden the engine would slow down..make some god awful noise and not even pull to redline in some cases.

Most of the time the gauge works...althrough i have noticed lately that its not always getting full boost either. It is possible for the intake manifold to not allow vacuum to get to the fuel pressure regulator by some sort of malfunction? We have been chasing this problem for months...they are about to replace ignition coils.

I noticed there is a syllanoid looking thing between the nipple for the vaccum hose and the intake manidfold...there are wires and a plug coming out of it. Does anyone know what this is? A sensor? A syllanoid controlling vacuum/boost pressures going to the fuel regulator? I need help! this could be the key to my car finally running right! Thanks in advance!

 

Inform your dealer there is a lemon law and make them fix your car this is rediculous.

 

I would be acclerating hard and all the sudden the engine would slow down..make some god awful noise and not even pull to redline in some cases.

I HAve this problem ever so often. I tought it was boost cut or fuel cut at first. But my selonoid is faulty is gettting replaced under warranty. There is a TBA about it to mitsu techs.

 

Yes there is a fuel pressure regulator selonoid. It is on the intake manifold right by the regulator. Im not sure why they have the selonoid, though.

 

The idle/vacuum fuel pressure solenoid is there to raise fuel pressure during certian temp's... You want to T in your boost guage before the fuel pressure solenoid...

bryan

 

Yeah, my boost gauge does that occasionally...the needle will stick on zero for a little bit before moving...no engine problems, though...I get a solid 20.5 PSI all the way up...no falloff at all...solid as a rock...

 

what are you readings on your boost gauge? How many psi of boost are you getting? Is your evo stock as far as boost goes?

 

The evo engine is stock. My engine problems have been ongoing...they replaces the wastegate syllanoid....and it seems like ever since then I am only getting 17 Psi....sometimes it boosts to 19 like it should...but only on slower acceleration...i never reach 19 on hard acceleration through 1st or 2nd. When I started the car today it read zero for a good 10 minutes while i ripped everything apart. My T fitting is in the correct location between the intake manifold and the fuel pressure regulator. The syllanoid thing I am talking about it on the intake manifold..where the vacuum line hooks to it. Well whatever the hell it is.... there was no vacuum and no pressure coming out of it when i pulled all the vacuum lines off...i am positive this is not right.

Note: I can hit the gas at a stand still and the needle still won't move.

 

mine doest do that. I just have spiking 21 and sometimes a hault in the boost. Mine i am positive is a boost solenoid problem

 

Is there vacuum right at the intake manifold? Before the electronic sensor? The guage should be hooked up right off the intake manifold. Not after any sensors. The fuel pressure solenoid is controlled by the ECU. It is between the intake manifold and FPR. It's job is to keep fuel from vaporizing in the fuel rail during hot starts, so the only time it should be activated is during certain start-ups. It could be faulty, or the ECU could be triggering it when it shouldn't be. I haven't looked on the Evo yet, so I'm not sure if the FPS is built onto the intake manifold, or is remotely located. By your description, it sounds like it is right on the manifold.

 

why dont you all just T up your boost guage at the diverter valve. no problems here for me.

 

I just bypassed the solenoid. no problems

 

I installed my T fitting according to this boost gauge install write up. Here is the picture from the website..... I have seen it installed on the next hose over too.....Perhaps I just need to move the location and it restricting vacuum there is normal?

 

I think I might just run it to one of the lines actually going to the BOV....that would be a more useful and accurate reading I think, but still at the location its currently in....is there any reason why there would be no form of pressure or vacuum coming out of it....even after driving alittle?

 

Mine is in that location and works perfectly.