I went to my local dyno yesterday to take my first shot at some dyno tuning with a wide band. First pass wasnt too bad as far as a/f considering how the rest of the day went. My a/f was around 14:1. So I did what I thought was logical and went to the % change to a/f vs. Rpm @ WOT and made a small change. I increased the number that was in there by 1 I think from 4000 rpm up. Well then it ran really lean. So we went the other way. And kept going the other way. By the time I had given up the best a/f I got was around 15:1 and my number from 52 or 5600 up were like -12% change. The last pass I decreased the number by -4 and it had no change on the a/f. I even made a change in the % change table vs/ cool temp in the temp range I was running in and nothing. The only thing I didnt do was make a change to the maf tables as I was advised it would not be a good idea.

Heres what I know:
-Datalogging wasnt working...program issue... so INJ D/C is out of the question but I know from earlier that at 80% tps my D/C was at 70% if that helps
-30# inj/ 45 psi of fuel @ WOT/ stock fuel pump
- LE3 heads and cam on a 110 LSA
- 02 mv on a short WOT blast and at idle are reading 800-900mv but the wide band is telling me lean and im throwing a lean bank and fuel system lean code

Thanks for any help. I'm worried about running this thing if the wideband is telling me its that lean even though I dont have any spark retard. Thought about running my fuel solenoid just to get some extra fuel in there

 

You need to add to PE to get more fuel, not take from it.

 

When I made my first adjustment I did add to it and it made it more lean. The a/f meter was maxed out and barely came down after reaching WOT. And when I took more away thats when it seemed to richen up.

 

At the dyno shop I use they will stop a pull if the A/F is that high. You should
get that figured out before you stress the motor again. Running that lean can't
be good for parts.

 

It may have been a fluke but + in the PE tables = more fuel.

often cars as they will warm up will get leaner and leaner. Thats probally what you saw.

 

Make sure your PCM goes into closed loop before you do the pull. PE tables don't seem to be used when in Open Loop.

 

Really.... I thought about that but I asked the dyno guy and he agreed that it should still use the WOT tables.

Rooster....
What I was going off of was in the help menu in tunercat they used an example of -5.1% change gives you a 12.5:1 richer a/f so we figured that taking away gives you more fuel. By the way, just for GP, the dyno guy is mainly a Ford man. We are both learning because he is looking into starting to tune chevy's but he already does fords and uses diablo sport for tuning.

Are the VE tables used in closed loop and when not in PE mode?

 

WOT AFR = 14.7 / (1 + %Change vs Cool/100 + %Change vs RPM/100)


if you put bigger numbers in the denominator you get a smaller number on the left side of the equation.

1/3 = less than 1

1/0.03 = greater than 1

By the time you drive up to speed on a decently warmed car on the dyno your usually OK. The only problems I've had is letting the car cool all the way down for a good power number and the first pull has a crazy AFR other times the car is nice and ready for the pull by the time you get it in 3rd or 4th gear.

Where are you dynoing at? We do $100 per hour with AFR here in charlotte.

 

I'm live in Newport. It's on the East coast near Morehead city and Atlantic Beach. I'll try adding this weekend and see if it will fatten up some. I appreciate it

 

No problem,

When you add some this time take bigger steps like 6-15

 

I will confirm that the positive number adds fuel in this table, I adjusted mine with a larger number Mine had originally a 7.4 from 5500 on up I was running in the lean side according to my cars O2s so I adjusted it to a 10.5 and it richened it quite a bit (too much) so I settled after lots of driving (and datamaster logging ) onto an 8.7. My cars O2s read a 750-920 (fluctuating) at WOT from 5000 on up now. I am going to try to lean it a bit , but I am going to recreate this on a dyno soon and see which way to go for power.

 

PE changes do nothing at all if you are in Open Loop, I mean nothing

I did the same thing, scratched my head, went -25 to lean her out and nothing, then I'm like ohh hmm... Tried in closed loop and what do you know every point made .1 AFR difference -10 points went from 12.7:1 to 13.7:1, tried again in open loop back to something like 11.2:1, the PE is only for Closed Loop, you want to edit AFRin open loop? Simply, either the Open loop vs. temp table to alter or the MAF table works.

 

So every pass on the dyno I have to wait for the timer to time out to get into closed loop assuming everything else is right for closed loop and then check my adjustments. That would explain a lot because liek I said the last three passes I made changes and it had no effect and I was maxed out on the lean side at idle. I'll make some big changes htis weekend unless I get to it sooner. Thanks everyone and Ill post up the results.

 

I need some clarification here the open loop WOT will be in the AF vs temp?
and the closed loop will be in the WOT vs RPM correct?

 

Also use this table that LJ made up
http://para.noid.org/~lj/PCM%20Tutorial/DynoTune.zip

It make the fuel tuning a whole lot easier.

More information at http://para.noid.org/~lj/PCM%20Tutorial/PCMtutorial.htm