Just bought an evo! having issues though... - EvolutionM - Mitsubishi Lancer and Lancer Evolution Community

Notices
Evo General Discuss any generalized technical Evo related topics that may not fit into the other forums. Please do not post tech and rumor threads here.
Sponsored by: RavSpec - JDM Wheels Central

Just bought an evo! having issues though...

Reply

 
 
 
Old Jan 11, 2018, 01:50 PM
  #1  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Just bought an evo! having issues though...

So the car has an AEM wideband and digital boost gauge. The car boosts to about 20psi (manual boost controller) just fine, and the gauge reads boost fine as well.
Problem is, my idle vacuum is anywhere from -8 to -4 inhg, and I'm running rich basically all over the place. anywhere from 12-13.5 idle and cruising, and 10 or below under boost. Already replaced front o2 sensor.

I did a boost leak test at roughly 26 psi and the only leaks I could find is the bov (it's a go fast bits deceptor bov, definitely an older model though) and the oil cap was leaking quite a lot of air, so much so that I had to hold it down to hear any other leaks.
Both leaks got really bad over 25psi, so I don't see any issues currently driving at 21.

Also, the car doesn't run like ****, which is weird with such a huge vacuum leak.

I already tried changing the power source for the gauges.

Is there a way to check vacuum on evoscan? I'm thinking maybe the gauges are bad.

Any ideas?
mct9891 is offline  
Reply With Quote
Old Jan 11, 2018, 05:23 PM
  #2  
Evolved Member
iTrader: (17)
 
hutch959's Avatar
 
Join Date: Nov 2004
Location: Chattanooga, TN
Posts: 603
Thanks: 0
Thanked 18 Times in 18 Posts
compression and leak down test
hutch959 is offline  
Reply With Quote
Old Jan 11, 2018, 05:41 PM
  #3  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Originally Posted by hutch959 View Post
compression and leak down test
did a compression test when I bought it, all good there.
mct9891 is offline  
Reply With Quote
Old Jan 11, 2018, 06:26 PM
  #4  
Evolved Member
iTrader: (68)
 
BluEVOIX's Avatar
 
Join Date: Mar 2007
Location: IL
Posts: 1,945
Thanks: 0
Thanked 18 Times in 16 Posts
What mods do you have other than the mbc and gauges? Does it have CAM’s ?
BluEVOIX is offline  
Reply With Quote
Old Jan 11, 2018, 09:21 PM
  #5  
Evolving Member
iTrader: (1)
 
Evo47's Avatar
 
Join Date: Mar 2014
Location: Murica
Posts: 127
Thanked 3 Times in 3 Posts
Bad tune?
Evo47 is offline  
Reply With Quote
Old Jan 12, 2018, 12:26 AM
  #6  
Evolved Member
 
Join Date: Aug 2011
Location: somewhere
Posts: 529
Thanks: 0
Thanked 1 Time in 1 Post
Originally Posted by mct9891 View Post
did a compression test when I bought it, all good there.
what were the compression numbers?
babaz7 is offline  
Reply With Quote
Old Jan 12, 2018, 01:40 AM
  #7  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Originally Posted by BluEVOIX View Post
What mods do you have other than the mbc and gauges? Does it have CAMís ?
TBE, intake, upper and lower intercooler pipes, mishimoto radiator, no cams.
mct9891 is offline  
Reply With Quote
Old Jan 12, 2018, 01:42 AM
  #8  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Originally Posted by babaz7 View Post
what were the compression numbers?
~125 across the board. It's a 9, so I've read these numbers are normal.
mct9891 is offline  
Reply With Quote
Old Jan 12, 2018, 04:54 PM
  #9  
Evolved Member
iTrader: (17)
 
hutch959's Avatar
 
Join Date: Nov 2004
Location: Chattanooga, TN
Posts: 603
Thanks: 0
Thanked 18 Times in 18 Posts
wonder if your TB butterfly is leaking badly?
maybe that why it doesnt have any vacuum and your boost leak check is pushing a ton of air in the motor.

or thinking more... (out loud)... maybe a IAC valve is faulty
hutch959 is offline  
Reply With Quote
Old Jan 12, 2018, 05:01 PM
  #10  
Evolved Member
iTrader: (10)
 
Pal215's Avatar
 
Join Date: Apr 2008
Location: San Diego, CA
Posts: 1,869
Thanked 102 Times in 96 Posts
This sounds like a tune issue to me. Have the injectors been changed since you bought it?
Pal215 is offline  
Reply With Quote
Old Jan 12, 2018, 05:20 PM
  #11  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Originally Posted by Pal215 View Post
This sounds like a tune issue to me. Have the injectors been changed since you bought it?
Nope, I checked via ecuflash and compared to a stock rom, basically only things that were touched is the high octane fuel and ignition maps. Even loaded a stock (tephrav7) rom and still the same thing.
mct9891 is offline  
Reply With Quote
Old Jan 12, 2018, 05:21 PM
  #12  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Originally Posted by hutch959 View Post
wonder if your TB butterfly is leaking badly?
maybe that why it doesnt have any vacuum and your boost leak check is pushing a ton of air in the motor.

or thinking more... (out loud)... maybe a IAC valve is faulty
Would that cause rich cruising as well?
mct9891 is offline  
Reply With Quote
Old Jan 12, 2018, 05:26 PM
  #13  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Update, now it's saying 0 vacuum, unless I give it some gas it'll fluctuate between 0-4 inhg. I pulled the line off the sender unit and there was indeed vacuum. Thinking maybe it's a bad sender, but that still wouldn't explain the richness.
mct9891 is offline  
Reply With Quote
Old Jan 12, 2018, 06:58 PM
  #14  
Evolving Member
iTrader: (24)
 
wht95scort's Avatar
 
Join Date: Sep 2007
Location: NJ
Posts: 252
Thanks: 0
Thanked 7 Times in 5 Posts
Possibly a bad sender happens quite often with the aem gauges. You can hook up a mechanical gauge to verify. Can get a cheap one at harbor freight.

as for the rich condition large vac leaks, larger injectors are installed and not scaled right. If you still have Evap on the car possibly the canister is saturated with fuel.
wht95scort is offline  
Reply With Quote
Old Jan 13, 2018, 02:16 AM
  #15  
Evolving Member
Thread Starter
 
Join Date: Sep 2011
Location: New Brunswick, NJ
Posts: 192
Thanks: 0
Thanked 1 Time in 1 Post
Originally Posted by wht95scort View Post
Possibly a bad sender happens quite often with the aem gauges. You can hook up a mechanical gauge to verify. Can get a cheap one at harbor freight.

as for the rich condition large vac leaks, larger injectors are installed and not scaled right. If you still have Evap on the car possibly the canister is saturated with fuel.
Would the car run like crap if there was that much of a vac leak?
mct9891 is offline  
Reply With Quote

Thread Tools
Search this Thread
Quick Reply: Just bought an evo! having issues though...


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.