paw

iTrader: (1)

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

derek_silvy

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.

one03sierra

iTrader: (1)

yay man he will have to tune for that.

paw

iTrader: (1)

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?

zippy

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.

paw

iTrader: (1)

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?

derek_silvy

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

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

paw

iTrader: (1)

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?

derek_silvy

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.

BigTex

iTrader: (16)

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.