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So I noticed my 02 numbers dropped at idle, should I add fuel?

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"Turbo-T"

V6 on steroids
Joined
Jan 10, 2007
Messages
7,393
Well I just finished installing my new 3 inch straight shot exhaust, with Dynomax Ultraflow muffler and I also installed a used 3 inch down pipe.

All of this replaced a stock down pipe, which was wheezing thru a shade tree mechanic 2 1/4 straight pipe where the cat used to be, and thru a pair of (no kidding) 2 inch pipes :eek: into a pair of Flowmaster 40 series delta flows :eek: :eek: and on out the rear.

Before I removed the old exhaust I noticed whenever I started my car and until it warmed up, the 02 numbers on the Scanmaster were usually in the upper 700's.

Well today I start my car for the first time with the new exhaust. I didn't check to see what the Scanmaster was reading because the first thing I immediatley did was start checking for exhaust leaks.

However I did notice once warmed up the readings were in the 400's and evnetually in the 500 range.

If I blip the throttle it gets into the 680 range and went to 703 briefly.

Now I would guess since I have opened up the exhaust this would naturally make the car run leaner correct?

But before I take this car out on the road should I bump up the fuel curves any via the turbo tweak chip?

Also before I did all of this I checked my fuel pressure and it was at 43 PSI static, and increases 1 PSI per lb of boost.

Thanks! I'll post a video and pics later.
 
Perfectly normal for o2's to swing low while motor is idling and cruising.

Tune idle and cruise off your BLM#. If your # is running high (above 128), add fuel to bring the number down. If it's low take fuel out and the # will climb. 10 plus or minus 128 is just fine.

Tune WOT off o2# verses knock. Tune for 780-800mv at the top of third. If you see knock, richen wot in the chip. If all seems well and o2's are above 800, trim a little wot fuel.

Remember, tune idle and cruise off blm and wot off o2 verses knock.

Good luck.....:biggrin:

Rick
 
Top of third is like 4800-5800 rpm depending on your cam range but you get the idea. ;) :D
 
I just made another post on this after taking the car for a spin and learning now I can suddenly get as high as 26 PSI.....and probably higher if I really wanted to but I didn't of fear of blowing something even with the Alky going....

But I found even in 3rd at 816 mv I managed to get 5.6 KR, I immediately lifted. I did find at cruise the block learn is at 115 to 117. It's at 123-124 sitting in park in the driveway.
 
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