everyone keeps referring to their AF across the ENTIRE range as ONE #...for instance "i'm running real safe at 11.5!"...

but shouldn't you look at more than just the final number at WOT? 11.5 at WOT doesn't mean you might not be running lean at other intervals correct? i realize i'm running a little lean in certain areas w/ my chip even though at 5400rpms i'm at 11.5...

so what exactly should we be looking for? how fast the AF drops? are they're other "markers" in the rpm range that we should consider instead of only at WOT?

 

ttt

 

Well, unless you have a wide band A/F meter installed on your truck, all you are going to be able to measure is WOT A/F on a dyno. It's good info to have obviously, but at the same time, you should always consult your tuner to go over the graph. There are several reasons for this. 1- some people just don't fully understand what it means. 2- sometimes the A/F readings aren't legit (sensors going bad, poor sampling, dyno operator error). 3- you can sometimes see things other than A/F by what the readout shows. Typically, I shoot for a specific value across the page. Sometimes customers will dyno their trucks, and they will have an A/F that's off in certian areas, and then we can use that info to tweak their chip finer.

What you really want to see is from about 300-400 rpms AFTER the sampling rpms shown on the readout. In other words, if your dyno starts at 3000 rpm, start looking at your A/F about 3400 or so. Most people will notice that A/F is always high on initial sampling, like 16:1 or so, then it should quickly drop down to actual A/F withing a few hundred rpm. If your graph does not drop down quick, that's usually a sign of the dyno A/F sensor going bad (they read slow).

Like I said though, best thing to do is discuss your reading with your tuner, so that he can explain in detail what's on there, and so that the owner has a better understanding of what's going on. The more the truck owner knows, the less chance there is he'll damage his truck.

 

thanks for the info sal. we're going back up to FLP to dyno next weekend and i will try your new reburn out. hopefully it nets me good power and runs safer than my current chip (worried it might be a tad lean at certain intervals..)

i'll scan and post the results...