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

 

You doing something stupid like venting your BOV to atmosphere with a MAF sensor in place?

 

whaaaaa pssshhhhhhhhhh

 

nope, not running a blowoff.

 

that would make him run rich during shifts. metered air out, corresponding gas still goes in.

 

Are you using a Uego wideband? My does a real quick blip to 10 sometimes after a shift...but mine is like super fast...

 

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.

 

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.

 

i vote gremlins

 

100% agree...not running a BOV IMO is honestly retarded regardless of boost levels.

 

rad days then, thanks for the thoughts, ill get my hands on one and hope that will help

 

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.

 

mine does the same.

 

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

 

have you tried anything to get it to stop? did anything even help a little?

 

^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?

 

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.

 

no because the event lasts for maybe 1/2 of a second.

 

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.