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Old 09-24-2008, 05:12 PM   #1
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Default Rich During shifts

I have a 94 w/ saab t3, probe ic, green tops, begi afpr, running 5 psi. fuel pressure for afpr is at 40 psi. now every time i shift it goes way rich, anywhere from 10-1 to 12-1. always happens, no matter if im in or out of boost. ive tried changing fuel pressures, but still happens from 35-50 psi. ive tried to search here but havent come up with anything. any suggestions? thanks Paul
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Old 09-24-2008, 05:34 PM   #2
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You doing something stupid like venting your BOV to atmosphere with a MAF sensor in place?
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Old 09-24-2008, 05:35 PM   #3
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whaaaaa pssshhhhhhhhhh
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Old 09-24-2008, 05:45 PM   #4
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nope, not running a blowoff.
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Old 09-24-2008, 07:06 PM   #5
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Originally Posted by Savington View Post
You doing something stupid like venting your BOV to atmosphere with a MAF sensor in place?
that would make him run rich during shifts. metered air out, corresponding gas still goes in.
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Old 09-24-2008, 07:16 PM   #6
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Are you using a Uego wideband? My does a real quick blip to 10 sometimes after a shift...but mine is like super fast...
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Old 09-24-2008, 07:19 PM   #7
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Originally Posted by tronik View Post
that would make him run rich during shifts. metered air out, corresponding gas still goes in.
yes, thats what he was getting at. but im not running a blow-off.
could that be the issue? the metered air gets bounced off the throttle plate when it closes, while the injectors are still spraying in the corresponding amount of fuel? maybe i should try running a recirculated BOV.
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Old 09-24-2008, 07:23 PM   #8
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yeah, i have a UEGO, but its not a quick blip. it will go really rich for 2-3 seconds. depending on how im driving (normal or sporting).
i also just noticed that it will go rich for a second everytime i let the throttle close. if i come to a light and let off it goes way rich (10-11) then go lean like normal.
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Old 09-24-2008, 07:25 PM   #9
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i vote gremlins
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Old 09-24-2008, 07:49 PM   #10
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Quote:
Originally Posted by NA8CSON View Post
maybe i should try running a recirculated BOV.
100% agree...not running a BOV IMO is honestly retarded regardless of boost levels.
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Old 09-24-2008, 07:52 PM   #11
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rad days then, thanks for the thoughts, ill get my hands on one and hope that will help
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Old 09-24-2008, 08:32 PM   #12
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holy ****, you had no bov all this time? wow
ill be surprised if your turbo is still ok
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Old 09-24-2008, 09:27 PM   #13
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Quote:
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holy ****, you had no bov all this time? wow
ill be surprised if your turbo is still ok
He said he's only running 5psi, I think he'll be fine.
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Old 09-24-2008, 09:40 PM   #14
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mine does the same.
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Old 09-24-2008, 10:04 PM   #15
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i would say it's normal to be rich between shifts because you close the throttle and still have some fuel spraying, but i think 2-3 seconds is too long and probably because of your bandaid setup with larger injectors
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Old 09-24-2008, 10:42 PM   #16
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Originally Posted by Braineack View Post
mine does the same.
have you tried anything to get it to stop? did anything even help a little?
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Old 09-24-2008, 11:00 PM   #17
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^Yup, bandaids with larger injectors and fuel pressure not bleeding off fast enough.

NA8C, fill out your signature and your profile... you used the word RAD, and in the last 10 years, the only two people I've heard use that are a Canuck and an Aussie. Put a short list of mods in your signature.

Also, you said it goes rich 10-12:1... which isn't really all that rich when speaking of forced induction. If that's the richness out of boost, what the hell are you running for AFR's in boost. You mention changing fuel pressures from 35-50psi... is that your base ~0 fuel pressure or the pressure you're seeing at 5psi?
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Old 09-25-2008, 03:17 AM   #18
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First off, i use rad all the time.
secondly, in boost i see AFR's from 14.5 to about 12.3.
first i had the zero point pressure high, then lowered it with no change in afr while shifting. but now its set to 40 at the 0 point.

is that better samnavy.
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Old 09-25-2008, 09:49 AM   #19
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Quote:
Originally Posted by NA8CSON View Post
have you tried anything to get it to stop? did anything even help a little?
no because the event lasts for maybe 1/2 of a second.
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Old 09-25-2008, 10:59 AM   #20
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You should be shooting for no leaner than about 13:1 in boost... and upwards of 11.5-12:1 towards your higher boost. The only reason your motor is still intact is because of the low boost you're running.

Begi says your ~0 fuel pressure should be about 48psi on stock injectors.... perhaps low 40's on 305's, but then you run the risk of lean-ness in the midrange, which you're getting in spades.

I would do an overhaul of the BEGi AFPR... perhaps the diaghram in there isn't functioning properly and holding fuel pressure too high for too long in vaccum.

The math for your current setup says you should run 45psi at ~0 and around 70psi at 5psi.
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