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Feels like BoostLeak/Fuel Cut cant figure out

DSM_PWR

Proven Member
2,459
18
Oct 12, 2007
Austin, Texas
OK so i have done Boost Leaks tests with soapy water and have found no boost leaks...
I have 680cc with the safc about -8/-12 across the hi throttle board with the wideband reading 11:1-11:5

Im usually hitting around 22lbs-24lbs of boost with 50/50 mix of e85 and 93... but one day as im on the highway my car feels like it "hit a brick wall" at 17-19lbs. I cant figure out why its doing this and driving me crazy:cry:
 

boosted86

Proven Member
415
4
Sep 7, 2005
Weston, Florida
ok so i still cant find the problem and its even gotten a bit worse. Now i cant even go WOT on 15lbs, no matter what boost im at, the car cuts off at 5500rpm. And i have absolutely no boost leaks (trust me, ive checked).

Also, my wideband reads really lean around 14:1-17:1 through WOT which leads me to believe my injectors are going out? anyone have a different thougth? maybe fuel filter??

During cruising mode it stays steady at 14:7 and i get same gas mileage...

woo, well thats deffentily your problem, 14;7 at WOt is dangersly lean(i dont even think N/A's run that lean at Wot) your getting heavy detonation(really high) and thats why your feeling that "fuel cut feel".again as stated before, post a log. and see what your timing looks like from 4k to redline(i bet you it crazy low)
 

DSM_PWR

Proven Member
2,459
18
Oct 12, 2007
Austin, Texas
Yea you can feel timing being pullled. BUT it just started showing lean the other day. When i first posted this problem it showed 11:1 just fine and now its getting lean. Ill try to work up a log when i get a chance.

Also my bov flutters now, would that cause anything? Ive tightened it to HARD and all the way SOFT and still flutters, no leaks and the vacuum line is great:confused:
 

boosted86

Proven Member
415
4
Sep 7, 2005
Weston, Florida
if your wb is acting up on you, then i wouldent guestimate your a/f( you dont want to mess with that, and if timing is being pulled, than your getting knock,which can really only be from 3 things.;1 to lean of a a/f 2; to high of intake temps;3; phantom knock.

if your bov is going threw compressor surge, and all your vac lines are connected like you say,and you have adjusted in both directions(mine is extreamly sensitive; it has to be in the right spot not to flutter) then i would say that your bov itself is at fault(bad spring,clogged valve,etc.)

also , what do you have your bpr7's gapped to? i had similar problems a while back now that i rember, iwas on the dyno and i had my 7's gapped to about .26 and my car was braking up at top(kinda hitting a brick wall) we re-gapped them .28 and problem solved.
side notes** evos come gapped at .24 from the factory, just to give you an idea on where your gap should be at.
 

DSM_PWR

Proven Member
2,459
18
Oct 12, 2007
Austin, Texas
Ok so finally had time to run a log. This was on 14lbs no e85 just straight 93 pump. Like i said before, my sample rate suck :notgood:

RPM o2 Timing AirFlowRate
2894// 96// 11// 9.870588
3363// 98// 9// 13.96459
3945// 96// 10// 18.1584
4605// 96// 9// 23.53094
5253// 94// 12// 28.53238
5925// 92// 15// 30.77184
6539// 1// 15// 18.00833
 

DSM_PWR

Proven Member
2,459
18
Oct 12, 2007
Austin, Texas
if your wb is acting up on you, then i wouldent guestimate your a/f( you dont want to mess with that, and if timing is being pulled, than your getting knock,which can really only be from 3 things.;1 to lean of a a/f 2; to high of intake temps;3; phantom knock.

if your bov is going threw compressor surge, and all your vac lines are connected like you say,and you have adjusted in both directions(mine is extreamly sensitive; it has to be in the right spot not to flutter) then i would say that your bov itself is at fault(bad spring,clogged valve,etc.)

also , what do you have your bpr7's gapped to? i had similar problems a while back now that i rember, iwas on the dyno and i had my 7's gapped to about .26 and my car was braking up at top(kinda hitting a brick wall) we re-gapped them .28 and problem solved.
side notes** evos come gapped at .24 from the factory, just to give you an idea on where your gap should be at.

I dont thnk my wideband is off, its only a month old

I loosened my BOV all the way soft so it doenst surge anymore, although it wont blow off under low boost but its better than compressor surge. EEK!

I have mine gaped at .29, the tips are a bit grey which is wierd because i just changed them the 1st of the month. I guess the e85 really does foul them quicker
 

DSM_PWR

Proven Member
2,459
18
Oct 12, 2007
Austin, Texas
I Found the problem and just incase anyone else has the same symptoms,

It was the MAS!

My friend used my MAS and he started getting fuel cut around the same RPMs, so now i have a MAFT setup and runs great!:thumb:
 
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