Tuning AFR - quick question - Tuning Forum

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Tuning AFR - quick question
Monday, September 24, 2007 12:34 PM
I finally got my new WB sensor so ive started to fine tune the cav. Now in WOT as soon as i hit 9lbs/wastegate opens, it jumps to like 13.5ish - leans out quite a bit. Its pretty damn close to right on the money at WOT but as soon as the wastegate opens it reads lean. Now im just wondering if because i have an atmospheric dump which is obviously before the WB sensor, would it affect the reading at all? i can see why it might, but i can also see why it wouldn't effect it. im just wondering if im seeing it lean out because of the rpm range at my max boost and its just coincidence or what... im starting to richen it up there, as ive only run about 2 logs and im updating the tune again tonight. and today i kept it our of boost because its within reasonable limits until WOT after 9lbs. still need to fine tune it but its getting there. any suggestions?




Re: Tuning AFR - quick question
Monday, September 24, 2007 2:46 PM
13.5 is WAY lean for a turboed car at any amount of boost!! thats crazy lean...

waste gate opening is not why you are lean, i had an open dump and it never leaned out the a/fs

add fuel! raise your fuel pressure if its to low, tune! richen it up a lot more then that as a starting point... atleast i would..

what size injectors do you have?
what do you have your fuel pressure set to?
stock pump?
how far from the downpipe is the wideband? what kind is it?

the more info you give the more peeps can help good luck man



|Forged 8.9:1 Wiseco Pistons|Forged Eagle Rods|HPTuners|60trim|Tial Wastegate|
|Precision Intercooler|2.5" Exhaust|2.5" Charge Pipes|630CC Mototron Injectors|
|Stock: Fuel Pump, Transmission, Manifold, TB, Head, Head Gasket, Ignition, Suspension...|
Re: Tuning AFR - quick question
Monday, September 24, 2007 3:12 PM
An atmospheric dump or a reroute past the sensor will move less gases across the sensor, but it in no way changes the mixture ratio. Like Acer said, you are either maxing out your injectors or you need to tune more.


-

"Youth in Asia"...I don't see anything wrong with that.
Re: Tuning AFR - quick question
Monday, September 24, 2007 7:14 PM
lol - not man, chika btw

i understand its lean thats why im richening it up. like i said, its close to perfect until like the w/g opens. im sure its coincidence as i still have a few areas to work on. basically idle/boost is what nees adjustments. normal driving its right on. i was just wondering if it could at all affect it. also like i said, its being tuned - its not at all done, thats why im babying it as much as i can as well as havent brought it to the track/dyno yet. lol its no where near done.

i have 36lb injectors (cobalt ss/sc stockers)
stock pump
inovate lc1 wideband
its right at the part of the DP where it bends to go under the engine... so maybe 2 feet down from the header give or take
hp tuners

still workin on it - slowly but surely - havent had alot of time. just noticed that when i was logging yesterday to tune it. ive since adjusted it a lil. have a ways to go but thats what its about.

last post till Oct lol...



Re: Tuning AFR - quick question
Monday, September 24, 2007 8:53 PM
do you have a afpr? an afpr can help tune your idle alot it should be lower then what you were running stock (55psi way to high) i ran about 40 from what i remember, or 35.... quick search will tell you....

it leaning out when the wastegate opens up is not a coincidence it leans out when it opens because when its opened, you are at max boost, putting the car through its highest need of fuel, which will make the worst parts of your tune shine.... like needing more fuel

the wideband should actually be about 8 inches away (further towards the back) from that bend... i think it increases the life of the sensor itself and increases the accuracy of the reading... but run a search to find that one out too... im 90% sure though...

lastly.... your a girl? give me a call chika chula




|Forged 8.9:1 Wiseco Pistons|Forged Eagle Rods|HPTuners|60trim|Tial Wastegate|
|Precision Intercooler|2.5" Exhaust|2.5" Charge Pipes|630CC Mototron Injectors|
|Stock: Fuel Pump, Transmission, Manifold, TB, Head, Head Gasket, Ignition, Suspension...|
Re: Tuning AFR - quick question
Tuesday, September 25, 2007 6:00 PM
Quote:

An atmospheric dump or a reroute past the sensor will move less gases across the sensor, but it in no way changes the mixture ratio.


Right, but it might change what the WB "sees." The wideband reports on the concentration of unreacted oxygen relative to the atmosphere. It tells you how much O2 is "in" the exhaust compared to how much is "outside." If the mixture is still reacting in the exhaust, and it's definitely a possibility that it is, dumping the exhaust might slow the reaction and show "more" oxygen. Or, if the dump is pointing at the outside of the sensor, the "outside" and "inside" ratios might be closer to equal, making the sensor show lean. Finally, the WBO2 sensor is most definitely affected by the temperature of the exhaust gases and the pressure in the pipe. A sudden change in either might throw the sensor off, depending on the particular sensor's design.

For an answer, I'd probably do a couple of very quick runs with the WB showing 13.5, then stop and pull the plugs to see if they're black, or tan, or white. The plugs tell you what's happening in the chamber. The sensor tells you what's happening in the exhaust.

-->Slow
Re: Tuning AFR - quick question
Tuesday, September 25, 2007 7:26 PM
slowolej wrote:

Quote:

An atmospheric dump or a reroute past the sensor will move less gases across the sensor, but it in no way changes the mixture ratio.


Right, but it might change what the WB "sees." The wideband reports on the concentration of unreacted oxygen relative to the atmosphere. It tells you how much O2 is "in" the exhaust compared to how much is "outside." If the mixture is still reacting in the exhaust, and it's definitely a possibility that it is, dumping the exhaust might slow the reaction and show "more" oxygen. Or, if the dump is pointing at the outside of the sensor, the "outside" and "inside" ratios might be closer to equal, making the sensor show lean. Finally, the WBO2 sensor is most definitely affected by the temperature of the exhaust gases and the pressure in the pipe. A sudden change in either might throw the sensor off, depending on the particular sensor's design.

For an answer, I'd probably do a couple of very quick runs with the WB showing 13.5, then stop and pull the plugs to see if they're black, or tan, or white. The plugs tell you what's happening in the chamber. The sensor tells you what's happening in the exhaust.

-->Slow
Very true...



P&P Tuning
420.5whp / 359.8wtq

Re: Tuning AFR - quick question
Wednesday, September 26, 2007 2:50 PM
slowolej wrote:

Quote:

An atmospheric dump or a reroute past the sensor will move less gases across the sensor, but it in no way changes the mixture ratio.


Right, but it might change what the WB "sees." The wideband reports on the concentration of unreacted oxygen relative to the atmosphere. It tells you how much O2 is "in" the exhaust compared to how much is "outside." If the mixture is still reacting in the exhaust, and it's definitely a possibility that it is, dumping the exhaust might slow the reaction and show "more" oxygen. Or, if the dump is pointing at the outside of the sensor, the "outside" and "inside" ratios might be closer to equal, making the sensor show lean. Finally, the WBO2 sensor is most definitely affected by the temperature of the exhaust gases and the pressure in the pipe. A sudden change in either might throw the sensor off, depending on the particular sensor's design.

For an answer, I'd probably do a couple of very quick runs with the WB showing 13.5, then stop and pull the plugs to see if they're black, or tan, or white. The plugs tell you what's happening in the chamber. The sensor tells you what's happening in the exhaust.

-->Slow


I can kind of see what you are talking about, if the WB sensor were placed in the dump section and not the downpipe/precat section of the exhaust. There will always be significant pressure in the downpipe regardless of how the dump section is routed. because exhaust gasses will continually flow through the turbine, but not necessarily the wastegated part. Perhaps I am not fully understanding what you are getting at.


-

"Youth in Asia"...I don't see anything wrong with that.
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