Here are my modest dyno results, 233/266. 2002 yukon 5.3. I have a K&N FIPK, Flowmaster cat back and westers tune. Is that normal numbers for those mods? What is the stock HP/torque on these trucks?

dyno shows i'm running rich. Do i need to have wester tune for that? What is optimal AF for my truck?

here's the link.
http://img17.exs.cx/my.php?loc=img17&image=watkins.jpg
http://img3.exs.cx/my.php?loc=img3&image=000_0264.jpg

 

I'ld call westers and yell him about your rich situation. You are dipping to about 10.8 @ 5K, which isn't too great.

What year is the truck? I'ld think that you should be seeing about 20 more RWHP.... maybe that will be there when you get your a/f ratio straight.

 

yay man he will have to tune for that.

 

Noob question here, I told wester I had high flow cats installed, but i have'nt put them on yet. Would that have anything to do with it running rich?

 

you want around 12.7:1. that is rediculous. that pcm should be back in his hands asap and he should be explaining that one. way too rich.

 

I told wester I had high flow cats installed, but i have'nt put them on yet. Would that have anything to do with it running rich?

 

If westers knows, then he should have that covered....

But hey, with a 10.8 a/f obviously something isn't covered.

 

does anyone know if high flow cats being tuned into the pcm and not being on the truck yet would cause it to run rich?

 

From what I saw on another post, when a higher flowing exhaust system is installed, more air passes over the o2 sensor at a faster rate, and it somehow confuses the PCM.... and Westers may have changed some parameters around. However, I doubt it will effect you that much! I'ld go ahead and get those cats installed.... it can't be more than 60 bucks, and then see how it does.

 

Couple of thoughts-

I assume you made the pulls in 2nd gear. 2nd gear pulls are lower than 3rd gear pulls.

Those big wheels and tires are robbing some power.

Was this a mustang type dyno? They will show lower numbers than the typical dynojet.

Isn't it interesting that the power is near identical between the two runs, yet there is a very large difference in the air/fuel readings between them. If the readings were accurate, I'd think there would be a power difference between runs. I'm thinking the A/F readings aren't 100% accurate in this case.