Well got the car dynoed today and had the A/F ratio read while I was there. The car is running really rich on top end and a friend of mine said that the O2's should correct this. Now my ? is that I thought that the O2's were only used for part throttle applications when in closed loop and the reverted back to the program when it reached WOT and ran off of the original programm. Who is right?

 

You are correct.

You need to lighten up the Power Enrichment table to affect the WOT mixture.

N/A ... around 12.7 - 13.0 to 1 is about good.

For Supercharged and Nitrous ... 12.0 to 1 is about good. A little richer won't hurt, might loose a couple of HP, but it will be safer.

Hope this helps

LWM

 

well your both right.

the o2s are reading the a/f ratio in pe mode (its not open loop) but the values are not being used. but the o2s could be adding fuel in pe mode or thet may not. it depend on the LT blms before you went WOT. if the blms are below 128 then the only fuel being used is what is in the PE table. but if the blmsare above 128 then it will add the same amount of fuel to the pe table as it was to the car before you WOT. so you could be runing 11.7 to 1 (factory setting) or richer depending on the o2s before you go wot.

the o2s will not correct for anything in WOT.

 

It is running 12 to 1 between 2500 -3000 then leans out for a minute then from 3700 -4400 it is back around 12 to 1 then richens up from there on finally at 6500 around 11 to 1. I would say this is way to rich what kind of power do you think I will pick up by leaning it out.

 

If memory serves, a Z06 on the dyno made 350 hp at the wheels, the A/F ratio was 12.0 to 1. They leaned it out to 12.6 to 1 and picked up 13 hp at the wheels.

GM does set their cars up on the conservative side. After all, it's in their best interests to do so.

I do remember my own car, an LT1 S/C car, stock internals with the stock Vortech FMU, the A/F ratio was a stunningly pig rich 10.5 to 1, and it made 395 rwhp, we put on a Super FMU and leaned it out to an A/F ratio of 11.8 to 1 and proceeded to make 423 rwhp, that was a gain of 28 hp ... not bad.

My present set up is also S/C and the A/F ratio was 12 to 1

Hope this helps

LWM

 

I went from 10:1 to 12.4-12.6:1 and picked up 15rwhp/17rwtq.

 

Ok so with a better tune I could get to 345 - 350 rwhp. Well should ?I send my graphs back to Bryan at PCMForless so he can adjust my program or go with my local shop so it can be perfect. The only problem is that my local shop wants $600 for a dyno tune and it will only cost me $75+ with Bryan and it will not be as good. What would you guys do.

 

LT1 editor or Tuner Cat ... around $200 if I remember correctly.

Lap Top computer ... you should be able to borrow one, or perhaps you already have one available.

3 pulls on a wide band dyno ... $150 - $200, and it shouldn't take more than that if you have an idea of what to do with the dyno results.

I myself went with LT1 editor ... never looked back, have used it to fine tune my set up about 20 times, well worth it.

OTOH ... if cash is short, then a PCM for less tune will definitely get you in the ball park, especially if they get your dyno data and all other pertinent information.

I don't think a dyno tune by itself is worth $600.

Hope this helps

LWM

 

Thanks where can you get LT-1 Edit for $200 there web site sells it for $550 just checking to see if there is anyone else that sells it. Tunercat will not work b/c I have an OBD2 car. PCMForless has already tried to adjust this once. When I first got my tune it was Lean so I sent him the Dyno data so he could richen it up I guess he eant o far with just wondering how it will work this time. Would love to get Lt-1 edit so I could save money save money and quite the guessing game with PCMForless.

 

You are correct about the price of LT1 editor. My car is a 95 and the price for that year is $200, $250 for the good version ... none the less, if you plan on keeping the car it is a worth while investment, and if you go that route, get the good version, the "expert" version. It has lots of features that make it much more useful.

Hope this helps

LWM