Me and my brother just installed his new Apexi boost gauge in his EVO and after going for a cruise to test it out we both thought it was boosting low.

it is claimed that it runs 19.5 @ 3500rpm and then tapers off to 16psi..

what the gauge read was-
1st gear- hitting 18psi around 3500 and rapidly tapering to 14
2nd hitting around 15-16psi(breifly) tapering to 12!
3rd+4th holding around 14-15psi

did some basic snooping around the engine looking for an easy fix problem. everything was a-ok so then i hit up lancer forums and found nothing...

just wondering if anyone knows anything about this, throwing in a profec-b shortly

 

pressure drop throught the IC migt explain 1 psi. where did u T the vac source from?

 

12psi in second = 4psi less than it should, not 1psi...

and if mitsubishi didnt account for I/C pressure drop they're pretty stupid.....


vac was t'd between the intake manifold and the FPR

 

damm dude I was trying to help no need to be a smart ***

 

Dont jump on his back for helping you out, and no, all car companies tell us the truth

 

Probably the BOV leaking, just like the 2nd gen Eclipse one used to.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FredoSP &raquo;</TD></TR><TR><TD CLASS="quote">damm dude I was trying to help no need to be a smart ***</TD></TR></TABLE>
He wasn't really jumping on your back, except that your post is kind of obvious and thus pointless. I don't think ANY manufacturer would quote pre-IC pressure as the boost level, because that would just be completely dumb and unimpressive, they want their cars to sound as 'cool' as possible, thus quoting crank HP, as opposed to wheel HP.

Are you running low-octane gas? The car comes with an electronic boost controller (determined by the ecu) so maybe it lowers boost, as well as pulling timing? Try getting new gas and resetting the ecu (probably just disconnecting the battery).

Also, a possibility, some cars (such as the SRT-4, I believe) have a target power, regardless of absolute boost. The SRT-4 should feel the same at 3000ft as at sea-level because it actually raises the boost! I think some Audi's are this way, as well. I doubt this is the case, but maybe the car 'thinks' it's making enough power, even though it's not at it's proper boost level!

If everything is in proper order, just slap on an MBC and call it a day.

 

Try getting the vacuum source from somewhere else?

 

Wasnt trying to be an *** fredo, i didnt insult you...


-Always filled with 93 octane gas.

-"The car comes with an electronic boost controller (determined by the ecu) so maybe it lowers boost, as well as pulling timing?" - YES, but it is supposed to hit 19.5, and then by redline taper to 16 while pulling timing.

ECU has been re-set multiple time

Car is equipped with a Forge BOV, so it shouldnt be leaking

Car also has a K&N intake, which could be causing some overrich condition because of the MAF sensor giving off a different reading....... doubt it though

"Also, a possibility, some cars (such as the SRT-4, I believe) have a target power, regardless of absolute boost. The SRT-4 should feel the same at 3000ft as at sea-level because it actually raises the boost! I think some Audi's are this way, as well. I doubt this is the case, but maybe the car 'thinks' it's making enough power, even though it's not at it's proper boost level!" - Thats possible, I havent read anything about that on the EVO yet

"If everything is in proper order, just slap on an MBC and call it a day." -in the next couple months its getting Profec B, 3" Turboback, and Dynoflash'n the ECU... should make around 300awhp - im jealous


thanks for the help guys

 

dave, we read up on lancer forums about the Tap on the boost gauge and tapped it where the lancer guys were getting the best readings, between the I/M and the FPR..... im gonna find out where mitsu taps for the boost gauge (if you buy the factory option gauge package)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jerseykid609 &raquo;</TD></TR><TR><TD CLASS="quote">tap a source in the high pressure zone anywhere before the ic </TD></TR></TABLE>

For the boost gauge, or the MBC?

You want both to come from the manifold, that is all the matters.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boltz &raquo;</TD></TR><TR><TD CLASS="quote">
Car also has a K&N intake, which could be causing some overrich condition because of the MAF sensor giving off a different reading....... doubt it though</TD></TR></TABLE>


Nope, not possible. Don't worry about that.

 

Anywhere that has a signal right from the intake manifold will be fine.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boltz &raquo;</TD></TR><TR><TD CLASS="quote">dave, we read up on lancer forums about the Tap on the boost gauge and tapped it where the lancer guys were getting the best readings, between the I/M and the FPR..... im gonna find out where mitsu taps for the boost gauge (if you buy the factory option gauge package)</TD></TR></TABLE>

 

Forge BOV's are junk for our evos. Get rid of it, they have had big leaking problems

 

A manual mbc and a good blow off valve should fix that problem.
You will have steady boost.
EVIL

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by C-Murdock &raquo;</TD></TR><TR><TD CLASS="quote">Forge BOV's are junk for our evos. Get rid of it, they have had big leaking problems</TD></TR></TABLE>

not that i dont believe you, but do you have proof?

 

I have heard nothing but great reviews about Forge BOV in scooby's, this is the first bad one I've heard yet...

 

me too.... thats why we otped for forge...

we were going to do a hks ssqv and reroute it to the intake but we ended up going with forge

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kpt4321 &raquo;</TD></TR><TR><TD CLASS="quote">


Nope, not possible. Don't worry about that.

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

It has something to do with MAF readings. Go read some WRX forums; LOTS of them have problems with their aftermarket intakes, thus the reason people just do a drop in filter.... unless you upgrade the turbo

 

i'd return the car back to stock, and if it doesen't boost to 19.5 PSI, have the factory fix the problem.

It very well may be that your modifications to it have caused it to lower boost pressure.

I also HIGHLY doubt that the stock blow off valve will leak pressure unless it is defective, if its a factory peice i would imagine it would at the very least, hold at LEAST 22 psi of pressure without opening up.

 

good call, its a shame we had to break the stock air-box to get the MAF out

there was nothing we could do about it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lazerus &raquo;</TD></TR><TR><TD CLASS="quote">if its a factory peice i would imagine it would at the very least, hold at LEAST 22 psi of pressure without opening up.</TD></TR></TABLE>

the first gen eclipse bov's could hold around that pressure without leaking when the were crushed.... the stock EVO bov is like the second gen eclipse bov, plastic....

that doesnt mean that it leaks at 12psi like the second gen ecuffs, just that it is possible because they are very similar and for all i know they could be the same piece


speaking of which, im going to get my buddys stock 2nd gen bov, and compare the spring to the evo bov

 

if a stock EVO BOV is leaking pressure at stock boost, it's defective.

otherwise every evo would leak boost, or they would have a re-call on the part. Factory boost leaks wouldn't be good for mitsubishi.