HP and A/F curve, tune questions

[03marauder]

I got my car retuned last week at Sutton Ford in Matteson, IL. Sunday we had one of our chicken runs here in Chicago. I guess as I was leaving some of the guys were saying how the car didn't sound right. I had noticed it did sound a little different after getting it retuned. Another member told me today that it did sound a little off in the low rpm's, but in the higher rpms it sounded great, and this could be due to the A/F ratio. So along with this I will post a pic of my dyno graph and the A/F ratio graph.
Now, on to the questions. The air fuel ratio is mostly around 13, but in the low rpms it is high, and it does drop below 13 at times. Since I don't know a whole lot about this does the plot of the A/F ratio look ok, or does it need to be adjusted? And the A/F ratio was taken from a bung before the cats, which they installed for me.
The other thing. Looking at the HP curve it is not flat at all, mostly on a steady rise. Can the car be tuned to make the curve more flat, or is it dependant on the car? I understand the peak is not the important part, but it is the area under the curve right, and the flatter the better?
Thats all I can think of right now, if any more thoughts come I will post them. I guess I'm just looking for the thoughts of some of the more experienced/knowing members here. After all this is the best place for info on these cars. I'm wondering if I need to get the tune relooked at if the A/F ratio is off and could cause problems. Thanks for the help.

[jobrien8]

If they took your A/F before the catalyst, they must have removed the HEGO Sensors. When they do this, the ratio is determined by a preset table in the processor, which will run slightly richer. Best determination is to check with the HEGO's installed and another bung installed. This is how it's done in testing.
As for the torque curve, I have not seen a continually increasing value from any modular engine. Usually it flats from about 2200 thru 4000 rpm. Possible that it wasn't at WOT (bad throttle position sensor?).
Best that I can tell you.

[BillyGman]

I got my car retuned last week at Sutton Ford in Matteson, IL. Sunday we had one of our chicken runs here in Chicago. I guess as I was leaving some of the guys were saying how the car didn't sound right. I had noticed it did sound a little different after getting it retuned. Another member told me today that it did sound a little off in the low rpm's, but in the higher rpms it sounded great, and this could be due to the A/F ratio. So along with this I will post a pic of my dyno graph and the A/F ratio graph.
Now, on to the questions. The air fuel ratio is mostly around 13, but in the low rpms it is high, and it does drop below 13 at times. Since I don't know a whole lot about this does the plot of the A/F ratio look ok, or does it need to be adjusted? And the A/F ratio was taken from a bung before the cats, which they installed for me.
The other thing. Looking at the HP curve it is not flat at all, mostly on a steady rise. Can the car be tuned to make the curve more flat, or is it dependant on the car? I understand the peak is not the important part, but it is the area under the curve right, and the flatter the better?
Thats all I can think of right now, if any more thoughts come I will post them. I guess I'm just looking for the thoughts of some of the more experienced/knowing members here. After all this is the best place for info on these cars. I'm wondering if I need to get the tune relooked at if the A/F ratio is off and could cause problems. Thanks for the help.I don't know what you mean when you say that the engine sounds off, or not right during low RPM's. But your engine isn't going to sound any different because of an improper air/fuel ratio, unless it was so lean that it was pinging all over the place, and in that case, you would hear the pinging. However, your air/fuel ratio isn't lean at all. It's a little on the rich side. Normal air/fuel ratio for naturally aspirated engines is 14.7. That means that there's 14.7 parts air to one part fuel. A number lower than 14.7 is rich, and one higher than that is lean.

In general, the only engines that require a rich mixture are ones with power adders (ie., superchargers, Turbochargers, or Nitrous oxide injection). Usually the leaner you go with the A/F ratio, the more power you'll get, but at the same time, the more likely that detonation (aka "pinging") will occur which would be very dangerous for your engine. BTW, if those A/F ratios were taken by using a tailpipe sensor, then you can throw those figures out the window since tailpipe reading for A/F ratios can often be very inaccurate. To get accurate A/F ratio readings, a gole must be bored in your exhaust and a bung welded in there which needs to be before the catalytic converters, since the A/F ratio readinds should be taken before the cats for accuracy. I wouldn't trust any engine tuner who uses tailpipe sensors to tune engines.

[RF Overlord]

Help a brother out, here...

I was under the impression that the A/F should be richer than stoichiometric (14.7) under WOT, especially at higher RPMs, even without power adders...so it looks to me like he's running a little lean(er) than he should be...

Lidio?
Dennis?
Zack?
Bueller?

[03marauder]

The air fuel ratio was not taken at the tailpipe, it was taken at a bung before the cats. Personally I didn't know what was meant by the car sounding off at low rpms, that is just what other people told me, that it sounded different than previously. Obviously I can't hear the car from behind while I am driving it. I just know there was a little different sound to the exhaust note.

The torque curve was relatively flat, it is the top curve in the graph. The hp curve rises in the graph.

[FordNut]

Looks about right. Most tuners shoot for 13:1 at WOT, which is richer than optimal stoichiometric ratio. The PCM tries to adjust for 14.7:1 at normal throttle positions. The torque curve and hp curve look about right in the shapes below 5200. What looks strange to me is the hp curve dropping above 5200. What I normally see is the hp peaks about 5800-6000 and climbs rather than having a dip above 5200.

Apparently the tc was not locked up, so the data doesn't go down to 1500 like I normally see from my graphs.

[MitchB]

Ask Sutton what they changed. Give them your observations. See what they say.

Mitch

[Slowpoke]

this might help. I have nearly identical mods as you except for the exhaust. We got tuned at the sme place on the same dyno by the same guy.

my tune was great. no funny sound.

[Slowpoke]

i just realized that the scan was aweful and extremely difficult to read. We have a good scanner at the office - i will bring the printout there tomorrow and attempt a better scan.

[Slowpoke]

ok - here is a scan that is a little better than the one i posted earlier. Sutton's sotware prints very faint lines and they are tough to reproduce.

[03marauder]

ok - here is a scan that is a little better than the one i posted earlier. Sutton's sotware prints very faint lines and they are tough to reproduce.
Your hp and trq curves are pretty close to mine concerning the shape of them. So I should have nothing to worry about. I didn't think so. As far as the sound of the car in the lower rpms, i think that was just bogus. One of my friends who has a heavily modified Mach 1 said the car sounded better after the tune. And it appears as though the A/F ratio is just fine, from what I've seen. I'm sure they know what they are doing there for tuning, if not they would not have been recommended.

[Slowpoke]

if this was the first tune you've gotten you should have noticed a huge difference in performance after the dyno tune.

[03marauder]

I noticed a big difference in the performance. I had the tune from Alternative before, but Sutton wrote over it. I had the car dynoed a while back and was at like 256 rwhp, after Sutton did it I picked up 20 more. Alternative is just too far away for me to run up there for them to tune to the mods I've done. I just wish it would cool down around here so I can get out some night and go wide open.

[Rider90]

if this was the first tune you've gotten you should have noticed a huge difference in performance after the dyno tune.

I need to get one of them there fancy dyno tunes. After a K&N Conical, Steeda U/D pullies, and a PHP Intake Spacer I think its time. Might as well get my seat heater switches replaced...

[03marauder]

I need to get one of them there fancy dyno tunes. After a K&N Conical, Steeda U/D pullies, and a PHP Intake Spacer I think its time. Might as well get my seat heater switches replaced...
Yeah, those are next on my list. U/D pullies, intake spacer, and 4.10's. That should help nicely off the line. But then I'll have to think about a torque converter too.

[GA-Marauder]

Yeah, those are next on my list. U/D pullies, intake spacer, and 4.10's. That should help nicely off the line. But then I'll have to think about a torque converter too.
Just had T/C installed, along with shift kit and tune for more crisp shifts. Made a BIG DIFFERENCE. I know G-Techs are not the most accurate measuring devices, but I pick up almost 1/2 second improvement in 0-60 times according to it. I do know that it feels like it. My thanks to the guys at Team Ford (Steve and Mike Bradshaw, t/c and shift kit, Aric Carrion, tune) for their expertise.:bows: