Over Fueling 408

[overdrive915]

I have a 2001 LS1 Stroked to 408 with 1 3/4 inch headers with open exhaust no mufflers. The engine overfuels a lot ( black smoke clouds ) under quick/hard acceleration.
My tuner informs me that the O2 sensors are registering .1 volt to low ( .841 volts at WOT) on avarage and that the computer now assumes that the engine is lean and compensates by overfueling.
The 02 sensors are located in the middle of the collectors
He has tried to retune the car app 5 time and still no joy , he is using EFILive .
Is there any way that we can change the 02 readings , maybe aftermarket sensors or do I buy efilive and try myself with the help of efilive forum.

[SSpdDmon]

O2 issues at wide open throttle stem from normal driving. They only carry over to WOT if normal driving is lean. The stock O2's are ignored at WOT. If he's tuning your 408 based on the stock narrow band oxygen sensors (which are only good at detecting a 14.7:1 AFR), I'd run away real quick. If you're running open headers and he still has you in closed loop, I'd run even faster.

[Black02SS]

I agree. He really needs a wideband to tune the car WOT. SEVERAL have heard me say this, but to me tuning a car without a wideband is like building a motor without a torque wrench. Sure it can be done but do you trust it and know it is done right??

[overdrive915]

Thanks for the info will get hold of him and ask questions as per you advice

[dfe1]

Thanks for the info will get hold of him and ask questions as per you advice

You're wasting your time. If he hasn't been able to correct the problem by now, he really doesn't understand tuning. With the set-up you describe, he should have the system in open loop in which case the O2 sensor readings are irrelevant. SSpdDmon hit the nail on the head- run away.
Fast.
Really fast

[Doc]

If you do decide to get into tuning you have come to the right place. You will get great advice here. You will have to do your homework and put in the time and money. You will be rewarded for your efforts. If you don't have the time or cashe then look for an alternate tuner with as many referals as you can get. In the short term, you might want to consider a mail order tune from a sponsor just to be safe.

[overdrive915]

Thanks for all the feedback. I am convinced and have ordered EFILive from my agent in the U S A and should recieve it in about 2 weeks as I will still be able to use it on the trasmissions side of things.