ive now fitted my aem uego wideband gauge and its all up and running.
engine off it reads 14.7
idle 12.9 - 13.4
driving between 11 - 14
full boost 10.0 (full boost is spiking to 20psi, holding at 17psi on vnt)
im guessing that from the tech section post, my engine is running far too rich?
im running a vnt (14psi everyday, 17-20psi when bled off), piper 285cam (std timing)
help with this from someone who knows more than me is greatly appriciated
Do you know what the spec of your carb is? That'll give an iudea as to where it'll be over fueling.
i havent a clue tbh. it was done by jp on here.
im thinkin i should just start from scratch with a std carb
If you got a standard venturi carb now have a check to see what size they are now, most are easy to change back to standard. If you got large venturi i'd change the body to standard size one.
If you found out what you got now it could be improved on rather than buying new carb.
Idle seems slighly rich but can easly be sorted with the mixture screw 13.5 is a good figure to aim for.
General driving seems slighly rich I'm pressuming the 11 is as you open the throttle? if so it's not all that bad if you only see it for a few seconds.
full boost is very rich you should be 11.5 12 afr running that rich, (10's) won't be doing your rings any favors, sounds like you need to whip the carb off and see what jets/second stage your running.
Or just turn the boost up some more!
:edit: Mark beat me to it!
is there a to do guide on what the std jets should be?Originally Posted by Markey Mark (BD)
as far as im aware its a std venturi carb. is it a case of removing the jets and gettin a set of micro drill bits to see what fits what?
i used to run throttle bodies on a 2.0 16v corsa so carbs are all new to me
once ive found a way to control the spike abit more then im hopin to run it at about 20psi, mayb more if its still fueling safe enoughOr just turn the boost up some more!
:edit: Mark beat me to it!
Yeah in the articles section there is a guide on the carb and its standard jet sizes, ideally you'd need a set of micro drill bits to measure them and then to mod them when you work out how big they need to be.
Good start that its a standard size venturi (25mm), least you could still use the carb you have then.
i do have another carb but i believe thats been played with also, but i know the base of that one is knacked as it had a self tappin screw inplace of the idle screw
something like these to the trick?
http://cgi.ebay.co.uk/PRO-20-PRECISI...item19bf66fa3e
I would check the calibration of the gauge firstly before condeming the carb. Check and calibrate the se nsor in free air.
totally agree make sure you have free air calibrated the sensor, and the gauge.
Standard Jets should be
1.25 a/c
1.0 1st stage
1.0 2nd stage (non removable jet)
1.20 Main jet
25mm Venturi
Ok here is a quick guide to what jets to modify:
Needle jet - this can be increased in an attempt to stop the carb fuel bowl from emptying normally when running higher boost than standard (Dependant on setup) and normally only required when a high lift cam is in use that allows higher rpm's.
The 1st stage (the removable screw in jet that is inside the triangle enricher section) is only 1mm - if this has been increased then it'll get too rich when you give it alot of throttle, before boost comes on. Some tuners used to swap this jet around with the a/c! cheap skates, it made the fuel curve bloody horrible.
The 2nd stage only comes alive after a few psi of positive boost (This is where jetting is required).
Normal driving is a real pig, that NEEDS a smaller main jet (so stay standard as long as you can)!
The air corrector does't make a huge difference at normal driving rpm's, it has more effect on boost and higher up the range.
It's just a case if trial an error, playing with actuator pre-load & the little vane control thread once you have loosened the grub screw first. I doubt it will ever be perfect but you will get it close, I stil have a 1psi spike which I can live with
Did you mention you run 14psi daily and then turn it up for high boost 17-20psi (with spike). No point in having a low and high boost setting either matey, ditch the in car controller if that's what you have got
Even with your spike matey you will be able to still fuel for that by just leaving the jetting a little richer so if you am for 11.9's @ WOT ' the 17psi once the spike has dropped you should will have a little extra fueling to compensate for the spike.
What boost were you running when you got those AFR's readings?
Last edited by James5; 01-11-2010 at 16:57.
Id free air calibrate the sensor as said above, you should see 20.8 or roundabouts with engine off (cold engine)
from memory aem state there is no need to free air calibrate, ive never done mine
the readings were taken on full boost 17psi (20psi spike)
i didnt calibrate the sensor.
from cold with engine off im reading --- and the outter ring reads the very last red marker, although when you first turn the ignition on it reads 14.9 then goes up to ---
Fair do's sounds ok then mate
thats ok then. im sure i read somewhere about the different modes you can choose on the back of the gauge but im sure it said just to leave it on with its on. c1 or something?Fair do's sounds ok then mate
guess i'll just have to wait for my drill bits to arrive and get measuring on the jets
if you got this from Chirs at EFI then it doesnt need any calibration at ALL, i asked the same question when i got mine
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