i have a 99 prelude with a greddy kit on. normally my boost gauge reads 5.5 psi when i'm on it. but recently when i floor it it goes up to about 5 psi and when i hit vtec it drops down to 4 psi. is this a boost leak or something else. at first i assumed a leak, but then when i realized it dropped at vtec i didn't know what to think. thanks.

 

bump....anybody?

 

The reason that it drops at vtec is because the enginwe is injesting more air at that point. Maybe you have a vacum leak. Thats where i would start. Is your idle surging at all?

 

what do you mean idle surging? idle seems to be fine.

 

i just got done checking everything out, and i can't see anything loose or cracked. i don't know what the hell to look for. this is really pissin me off.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nic411 &raquo;</TD></TR><TR><TD CLASS="quote">i just got done checking everything out, and i can't see anything loose or cracked. i don't know what the hell to look for. this is really pissin me off.</TD></TR></TABLE>

Idle surge meaning when you Idle it kinda goes up and down on the RPMs.

 

no i don't have idle surge at all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by notanotherSC61 &raquo;</TD></TR><TR><TD CLASS="quote">The reason that it drops at vtec is because the enginwe is injesting more air at that point. Maybe you have a vacum leak. Thats where i would start. Is your idle surging at all?</TD></TR></TABLE>


Ok that guy doesnt know what hes talking about, just cause your car hits VTEC isnt going to cause you to lose 1.5 psi off boost. It might for maybe a second but the WG line will see the dip in boost loss and tell the WG to close a lil bit so boost will go back up. Is the turbo internal or external wg? If its external, look for any ware or anything that looks out of the norm. If its internal, the flapper opening could have developed some hairline cracks that are effecting boost delivery. I would check for cracks in the WG line and look for cracks and couplers that are not super tight. If you can, do a pressure check and see if you find any boost leaks. Also, the WG diaphram could have a small crack in it cause this issue as well...

good luck

Blaze

 

thanks man. i've checked the couplers and they look all good. i'll check the wastegate this afternoon. it is internal greddy 18g

 

this is a big problem with greddy wastegates. Look into and youll see all sorts of boost drop stories. Some company makes an upgraded wastegate. Also you can put a spring on the wastegate pole to increase its pressure

 

thanks a lot. i looked and didn't see any cracks or anything. i'll look into the upgraded wastegate or spring.