Ok im having some issues tuning this boost spike out of my greddy profec 2. I am trying to get it to hold 15psi- which I can do, but boost always spikes up like 1.5psi over the target before coming down to a sustained level.

I have messed with the set and gain over and over while keeping set gain at 0. I also turned the controller off and the gate held 8.7psi (spring pressure) solid all the way thru the powerband with no spikes so i know its a controller issue and not a boost leak.

My setup is tial 35mm gate/ revhard mani/ 3" dp

both the line goin to the wg (side) and to the controller are fed off the intake manifold/brake booster...

Like I said I can get it to hold 15psi but when the "peak boost" shows it reads 16.5psi, even though i cant see where it ever reaches 16.5psi, could it be it spikes between shifts or maybe right before the gate opens? ive had people watch the gauge and they cant see the spike

 

the only thing the greddy manual says for fixing a boost spike is to lower the set gain (but you are at 0) and to adjust the gain, it doesnt say up or down. maybe you can play with it to see whats up. i dont really understand why the last boost would say higher than what someone watching the display saw.

i know i had a little boost spike at the end of my dyno runs when i was getting tuned like right when the tuner left off it would spike, as measured by the dyno, didnt register on my defi gauge though. i dunno just thought id thow that out there.

 

Just throwing this out there but on the boost solenoid make sure the plastic cap on solenoid is not there and it is venting to atmosphere. Seen it happen before.

 

Is the person watching the boost, watching the display on the boost controller or a gauge? Ever think the gauge or display are off a tad bit?

If it is holding solid and not fluttering I wouldn't worry to much with it. Unless you see it spike up on your gauge and fall back down.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 &raquo;</TD></TR><TR><TD CLASS="quote">Is the person watching the boost, watching the display on the boost controller or a gauge? Ever think the gauge or display are off a tad bit?

If it is holding solid and not fluttering I wouldn't worry to much with it. Unless you see it spike up on your gauge and fall back down.</TD></TR></TABLE>
Exactly what I was going to say. When the boost holds fine is the gauge display the same as the controller display?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHCD16y8 &raquo;</TD></TR><TR><TD CLASS="quote">
Exactly what I was going to say. When the boost holds fine is the gauge display the same as the controller display?</TD></TR></TABLE>

i believe i read in his other post that his boost gauge is broken. so he is looking strictly at the ebc display. he is seeing steady boost of 15psi give or take a little but then the last boost feature of the profec is telling him boost maxed at 16.5psi at some point in the pull.

i dunno, im going to assume that its probably not that big of a deal. 1psi probably isnt gonna matter much anyways.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dpetro1 &raquo;</TD></TR><TR><TD CLASS="quote">

i believe i read in his other post that his boost gauge is broken. so he is looking strictly at the ebc display. he is seeing steady boost of 15psi give or take a little but then the last boost feature of the profec is telling him boost maxed at 16.5psi at some point in the pull.

i dunno, im going to assume that its probably not that big of a deal. 1psi probably isnt gonna matter much anyways.

</TD></TR></TABLE>

I think if he can't actually see it fluctuate and it reads steady, that it shouldn't be an issue.. kinda like my map sensor reading 10 psi when I am running 12 on my gauge.

 

yeah my "boost gauge" is messed up so i dont want to read off it- it reads 30" vacuum at idle lol.

So im reading directly off the ebc display, which i have in PSI mode.

Did a bunch more pulls just now and i watch the display as boost builds, i got it to where it builds and holds 15psi pretty rock solid, but my biggest concern is when i let off LAST BOOST is reading 16-16.5psi. I wouldnt really care but im just worried cause my max boost im tuned for is 18psi and i want to config the high setting for that, but im worried if i aim for solid 18 then ill be spiking to like 20 "apparently" according to the ebc....

I cant see the spike ANYWHERE but the ebc is saying its happening, my guess is right before i shift? Cause the vac-&gt;boost goes to 15 and holds, it doesnt go to 16.5 then drop to 15- it holds at 15, then after the pull the ebc is saying 16ish but i never see that....

grrr any ideas?

here is some more info: I have the solenoid inline with the top wg vac line, the NC port goes to the intake manifold, and the COM port goes to the top wg, NO is open.

Side port of the WG shares with the boost gauge
EBC Solenoid shares with the GM 3Bar

 

Can you set a warning with those controllers? Maybe set the warning at 16-16.5 and see what it does.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 &raquo;</TD></TR><TR><TD CLASS="quote">Can you set a warning with those controllers? Maybe set the warning at 16-16.5 and see what it does.</TD></TR></TABLE>

yeah you can, i set warning at 16 and had limiter (percentage it takes you down from your current boost) set to 50% and on the 15psi setting it would limit me. So i took the limiter off, left the warning at 15psi and did another pull, thing was flashing red and blue but display still read 14.9psi so im not really sure how the hell the limiter is supposed to function? I think maybe it starts warning you 1psi before the limit?

im gonna see if i can get a buddy to tape the ebc display and ill post a vid so you can see what im dealin with- its a mystery!