ok, hrc stg II w/ fmic, cat back, sfmu (dark spring), in tank/in line pump, stock injectors, no boost controller.


so tonite i decided to "hack" my wastegate vaccuum line into the intake manifold to keep from losing the pressure drop through the fmic.

everything is running fine, holding a steady 7 psi, no fade at all (used to be 5-6 psi). then all the sudden i notice my boost go past 7, to about 10 where i caught it and let off. weird. so i make a few more runs to test things out, and again, my boost guage jumps really fast to 15, where i let off immediately. now it didnt really seem like i was pushing 15psi, and my egt's werent skyrocketing. it just seemed like my boost guage was going crazy. although i guess i didnt really let the boost get out of hand, i let off as soon as i noticed it. vaccuum is still fine @18, engine is fine, seems like all of the IC piping is fine and not leaking, compressor fitting plugged, i dont really know what else to check... i really dont know what could be the cause, but i might just route that wastegate line back into the compressor housing.

so, i dont really know what the cause of it could be. the wastegate should be dumping that pressure @7psi no matter what. sometimes its holding at 7, sometimes its spiking like crazy.

is there a locknut or screw on the wastegate itself that may be stuck closed? other than that i really am not sure what it could be. you guys have any suggestions?

tia,

md3

Are you sharing that vacuum source with anything else - like BOV, EVAP, cruise control, boost gauge, etc. I have no idea if this will help, but try giving the wastegate it's own source to the manifold - don't share it with anything else.

Do you have the standard HRC downpipe goin on? How bout the cat - gutted?


95 Eclipse RS : 5 speed
15.943 @ 86.48mph
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hrc ghetto pipe, stock cat, test pipe sitting in my room.

as for the vaccuum source, its teed right close to the mani, and its the only tee in the line. i didnt feel comfortable adding another tee to the line i have just about everything hooked to, and my bov has its own dedicated line. of the three lines on the intake mani, its the 1 on the left (evap?) i would have to check my manual as to which one it is...

could it be too restrictive of an exhaust?

Ahh you hooked it up to the 3 way tee on the mani?? Try hooking it up like I did, using the brake booster vac line, and tee it off of there. Do you know what wastegate spring they shipped you? If its the stage 2 spring, then you will see about 10 psi, since you are not using a boost source right at the compressor, as HRC uses this higher psi spring to compensate for the IC pressure drop, so you see 8 psi. But it still shouldnt spike like that..

hmm. yea, i dont have my boost controller set up yet. im going to do that tonite. hopefully that can control it. its sort of wierd, because sometimes it holds steady, sometimes it just keeps rising.

isnt that brake booster line reeeaaally big?

Yeah, the booster line is pretty big, but i just got a tee at Autozone, that fit that line, and then the third tee nipple was just small enough too fit the vac line that goes to the MBC/wastegate. Its basically a reducer tee. Then i uses metal hose clamps on the booster line connectons to the tee, and ziptied the teed off connection for the MBC line. I forget matt, what stage spring did HRC give you? If you got the stage 2 one, then a MBC will not let you go below that setting. Thats why i like the 5 psi stage one spring, that way, you can go as low as 5 psi, and use the MBC to go up from there. If you got the stage 2 spring, you may want to keep the line to the wastegate comming off of the compressor, to keep boost levels safe. Then, you can use the MBC to fine tune the boost to 8 psi or whatever.

yea, its the stage 2 spring. im not even going to use the MBC now... it pulls hard at 7 psi, and i dont want anything more than that with stock internals.

when it seems to spike though, it doesnt seem like its pulling harder... it just seems like the boost guage keeps rising. makes me wonder if there is a small leak somewhere. i should make one of those pvc leak testers like you have matt... it was running fine this afternoon though. im afraid to drop it to the floor now with the spikes though. im staring at my guages every time i step on it.

dude, just stop on over and we can put the leak tester on. Didnt we test for leaks when we installed it? Haha i cant remember

yea, it seemed good when we did it. i want to definately rule that out though.

but yea, i can swing by. ill give you a call tomorrow about it.

well, it seems like i found the problem. one of the fuel lines from the sfmu had fallen onto the vaccuum line i tapped into, and was putting just enough of a blockage in the line right at the tee to throw off the signal to the wastegate. im really lucky i didnt break anything.

it now runs absolutely perfect and holds at 7 psi steady. i should have found that right away, but it was dark... oh well, thanks for the replies all!