need a little help.....
i just installed a hks intake and 5zigen catback exhaust....but for some reason my boost only reads about at 1.0 right now....but before the install running stock it was boosting 1.26....is this normal...?? or am i loosing boost some where...

 

If you are running stock boost controller, Then it's normal for not having full boost due to the extra air that the MAF is reading, thus telling the computer to bleed out the wastegate.

 

Could maybe try and reset the ECU and see if that helps too.....or buy a MBC or EBC and that will take care of that no boost problem :-)

 

anyone got other opinions...?? after i resetted the ecu the boost went to 1.06 intead of 1.0....so it helped a little bit....so does that mean if i want to boost more i'll have to buy a boost controller or get the car tuned??
thanks for any info...pretty new to this....

 

To get more boost, yes you'll need to buy a boost controller. And if exhaust is all you have, you won't or can't really "tune" anything without an SAFC, or some type of computer mod.

 

when I just installed my Apexi filter I lost 1psi of boost in every gear, same thing happened to my friend. We don't know what exactly is causing this. We just put in a MBC and problem solved.

 

Before you knock yourself out.. Be certain the MAF sensor is seated properly and not leaking air.. Make sure your DV (Diverter Valve) hoses are on tight, and the vacuum lines are connected since it was likely you had to move it or remove it to get at the stock parts to get the HKS Intake installed.

Changes like this should not normally cause boost to read lower.. a really wacky MAF reading could cause the ECU to think its overboosting and cut boost, but I don't think thats your problem.

First, A complete aftermarket exhaust system, downpipe and Cat (or Cat Delete) should actually cause an increase boost slightly and it will spool slightly earlier. Double check everything and verify everything. Also if you removed the diverter valve, be certain that when you reinstalled it, that it went back the way it came out and isn't reversed.

Our stock boost solenoid works by bleeding a set amount of pressure from the wastegate actuator through a solenoid. Therefore anything that can effect the pressure in the intake tract (a boost leak, less restrictive exhaust, etc) can effect the overall boost. My experience with this stuff is that it doesn't affect boost all that much (to the negative) so verify what you had done.

Also, be sure your boost gauge is working correctly. Its possible your boost is actually normal and the gauge is reading incorrectly. Many people have that problem if they splice into the DV line on the valve cover to tap for the gauge. Does the car feel weaker than it did before? (Within reason, honestly with no other modifications, the filter mod may make the car feel weaker anyway)

 

couple of things...if you just install a catback you could lose some boost due to no more butterfly valve on the muffler. Now if you installed a full turboback especially w/ testpipe you would be gaining boost. Also, boost is affected by temperature so when you got your 1.26 bar did you get it on a cool day? having said that, 1.0 bar is definitely low even if your mods affected your boost so it's worth checking your connections, clamps, gauge etc.

 

Oh yeah, good point, I forgot about that..