I just put the Innovate LC-1 and XD-16 wideband in my 04 mustang GT. I have mac CAI, Mac prochamber, Flowmaster mufflers, pullies and an Xcal2 tune. Now what I noticed is at idle, I'm seeing a start of 13.xx and rising a little to 15.xx. Now my ? is, at idle is that normal? And what should I expect safe while cruising. I haven't had a chance yet to take it out for a spin

 

Idle should be from 13 (cold start) to high 15's (warm). WOT should trim out to 13.5 to 12.5 on an NA car from 2800RPM to redline. Forced induction cars should run a little richer at WOT (11.5:1 is nice and safe) but about the same as NA at idle.

While cruising, it should be 13-15 and will probably bounce around a lot. Unless it's pinging the idle and cruise aren't terribly vital as far as safety goes and cruising at 14.7:1 isn't uncommon. WOT is where the metal meets the meat and there it should be stable and no higher than 13.5 from 3000rpm onward (13.5 is kinda lean to me but some tuners like it). Below 3000rpm you can see between 13 and 14.5 at WOT on most stock tunes.
a little rich (like 13:1) is cold start standard practice... richen it up and keep cold idle quality, when it's warm you can lean it out and the idle will stay smooth.

 

When getting your car tuned on a dyno, is it true most tuners shoot for a 12:5 A/F ratio because when you actually get the car out on the street it will be about :5 leaner than on the dyno?? I'm assuming because when your actually driving, the engine brings in more air.

 

your on this forum too?!

 

I don't think that's the actual reason for it. I've never seen a real difference in real driving @ WOT as opposed to WOT on a dyno other than intercooler temps and engine temps tend to be higher on dyno's than on the street/strip for obvious reasons. When I was learning the fundamentals of tuning my tuner/instructor told me it's just safer that way and I stopped asking questions since 12.5:1 was the standard practice of that shop.

If you get a crappy tank of gas having it a little richer is an extra measure of safety against engine damage from things like low octane causing detonation. It also tends to allow you to run maximum timing without pinging which makes more power. If you lean it out it's best to drop the timing a hair for the same reason but that usually pulls the power down a bit. So it all comes down to a balancing act.

Thanks to the mass air flow system, the fuel is delivered based on how much air actually enters the system, so ram air and things like that won't throw it off (and why really hot days kill power). Carbs are just as efficient in that respect as volume of air passing through them determines how much fuel is delivered.

 

Very good info as always. Thanks

 

Well mines around mid 12's WOT NA? So thats where I wanna be? And yes teal, I'm here also. lol

 

mid 12's is perfect from my point of view. I look for 13 on more heavily tuned cars with forged bottom ends cuz they can take a bit of pinging if they get some crappy gas. You should be quite happy with yours.