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Jester

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Hi to all,

I am trying to figure out how to make a fuel air mixture adjustment to my C4. I have changed the following K&N Tripple Cold air induction intake, Modified Throttle Body to 52mm and a granatelli Modified Mass Air Flow Sensor . I can smell raw fuel and can tell that it is running rich.

I did pick up a Hypertech Power Programmer that I intend to use but was not sure if that is what is needed to make the change. any help is greatly appriciated.

Greg : :eek

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Everyone here swears by a guy named Nic. Maybe he'll read this post and jump in to help. :thumbs

as far as i am aware, there is only one adjustment "screw" and that's to adjust idle - however, i'm told you are NOT supposed to mess with this. idle is to be adjusted via the computer - as is the air/fuel mixture.

i'm not sure the hypertech will let you program that stuff - never used one before - but Nic can tune about anything he can plug his laptop into (or your laptop if you have your own software)

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Those mods shouldn't have changed anything air/fuel wise that the computer wouldn't adjust automatically. Did you drive it for awhile to let the computer see the differences and make the changes? The O2s should see the rich setting and the computer should fix it. :thumbs Robert :burnout

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There is no mixture adj. on an LT motor. Modified or HP mass air sensors usually screw up the tune and dont add any power anyway. I would try the original maf and see how it runs. Make sure you put it in the intake tubes in the stock fact. installed clock position. Hopefully your orig. maf still has the fact. screens installed as it wont run properly without them. Do you have a modified fact. throttle body or an aftermarket unit? Mine is a bored out stock unit and when I got it back from the place that bored it out I had to spend alot of time setting the min. airflow throttle bypass (thats the idle screw that you typically dont mess with). If you have an aftermarket unit it should be fine as they come precalibrated. I would check for vac. leaks at the throttle body gask. and all the vac. lines. If you have a vac. leak the map sens. will read a low vac. level and think you need enrichment and send in more fuel. I would also try the stock airbox. On my LT4 it has the exact same hp with the stock airbox (cut lid & K&N installed) as with the stupid $300 aftermarket unit, and the stocker doesnt screw up your tune. C5's are prob. different, but late c4's have a pretty good stock airbox. Hope this helps...Joe

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Everyone here swears by a guy named Nic. Maybe he'll read this post and jump in to help. :thumbs

Thanks I hope he see's this post :devil

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There is no mixture adj. on an LT motor. Modified or HP mass air sensors usually screw up the tune and dont add any power anyway. I would try the original maf and see how it runs. Make sure you put it in the intake tubes in the stock fact. installed clock position. Hopefully your orig. maf still has the fact. screens installed as it wont run properly without them. Do you have a modified fact. throttle body or an aftermarket unit? Mine is a bored out stock unit and when I got it back from the place that bored it out I had to spend alot of time setting the min. airflow throttle bypass (thats the idle screw that you typically dont mess with). If you have an aftermarket unit it should be fine as they come precalibrated. I would check for vac. leaks at the throttle body gask. and all the vac. lines. If you have a vac. leak the map sens. will read a low vac. level and think you need enrichment and send in more fuel. I would also try the stock airbox. On my LT4 it has the exact same hp with the stock airbox (cut lid & K&N installed) as with the stupid $300 aftermarket unit, and the stocker doesnt screw up your tune. C5's are prob. different, but late c4's have a pretty good stock airbox. Hope this helps...Joe

Hi Joe,

Thanks for the info. The TB is modified so I will look into your sugestion further on that side, But I will say I did pick up some major torque with the changes it is like night and day. I will let you know what I come up with on the adjustment.

Thanks again

Greg

Those mods shouldn't have changed anything air/fuel wise that the computer wouldn't adjust automatically. Did you drive it for awhile to let the computer see the differences and make the changes? The O2s should see the rich setting and the computer should fix it. :thumbs Robert :burnout

Hi Robert,

I dont take it out much so it could be that it just has not been pushed hard enough yet, But the weekend is comming so I will take it out and throw the hammer down

Thanks

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Everyone here swears by a guy named Nic. Maybe he'll read this post and jump in to help. :thumbs

Thanks I hope he see's this post :devil

Nic's e-mail:

nicolas.desjardins@asu.edu

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