WARNING!!! Predator Tune May Be LEAN...

YtnGT · Nov 26, 2004

I just finished installing a wideband O2 meter. That is the good part. The bad part is that the predator tune (r50b) is causing a lean condition. It is not bad enough to cause detonation in my case but it was leaner than I would like. At 3000rpm WOT the a/f was 15 it dropped to 14.5 by 3700rpm and finally made it to 13.5-13.7 by 4500rpm.

I installed the factory HP tune (without making tuning changes) and the a/f is a nice steady 13.5 from 3K up (sometimes it drops to 13).

FYI wideband O2 kicks arse

raykrv6a · Nov 27, 2004

YtnGT said:
I just finished installing a wideband O2 meter. That is the good part. The bad part is that the predator tune (r50b) is causing a lean condition. It is not bad enough to cause detonation in my case but it was leaner than I would like. At 3000rpm WOT the a/f was 15 it dropped to 14.5 by 3700rpm and finally made it to 13.5-13.7 by 4500rpm.

I installed the factory HP tune (without making tuning changes) and the a/f is a nice steady 13.5 from 3K up (sometimes it drops to 13).

FYI wideband O2 kicks arse

The Ford HP factory tune was damn rich (10.5-12)on my car at WOT. This is the tune that came with the car and tuner said this was to keep the cats from getting too hot. When I installed the Predator tune, it was 10's-11. This was on a DynoJet and probably a tailpipe sniffer. Both tunes were lean at idle, but that's to heat the cat's up faster. Least that what the tuner said. I believe we set the af to 12.5-12.9 on mine and then adjusted the timing.

I believe I'm running 50a in my predator. I wonder if the tunes change much between versions. I don't want to have to buy dyno time everytime I download a new version.

jstreet0204 · Nov 27, 2004

I'd be willing to bet that MAF is what is leaning you out.

raykrv6a · Nov 27, 2004

jstreet0204 said:
I'd be willing to bet that MAF is what is leaning you out.

Good eye. Missed that.

billyfe390 · Nov 27, 2004

jstreet0204 said:
I'd be willing to bet that MAF is what is leaning you out.

Your right it is.

YtnGT · Nov 27, 2004

I am using the stock MAF... The C&L MAF was only used at the track. The 14.07 sec 1/4 time was using the C&L MAF & magnaflows. I guess my sig could be misinterpurted. My air intake is completly stock down to the air silencer.

I will go and install the predator performance tune again and see if I get the same results.

BTW nice guess on the MAF if I was using it and the predator tune I would be running even leaner.

billyfe390 · Nov 27, 2004

YtnGT said:
I am using the stock MAF... The C&L MAF was only used at the track. The 14.07 sec 1/4 time was using the C&L MAF & magnaflows. I guess my sig could be misinterpurted. My air intake is completly stock down to the air silencer.

I will go and install the predator performance tune again and see if I get the same results.

BTW nice guess on the MAF if I was using it and the predator tune I would be running even leaner.

As with anything diablo it will be lean.

and yeah your sig is a tad on the misleading side.

YtnGT · Nov 27, 2004

I just reinstalled the preformance tune and it is doing what I initially described... Leaner than stock but that is what it is supposed to be doing. I guess it would be kind of hard to produce more power without being leaner.

It just bothers me being at 14 a/f & WOT 4000rpm... But other times it manages to get down to 13.5-13.7 a/f at WOT 4000rpm.

I just wanted to warn people that they could be running leaner than they might like by using the "canned" performance tune.

I think I will modify the stock tune, more timing.

YtnGT · Nov 27, 2004

raykrv6a,
If your tuner used a tailpipe sniffer (wideband O2) and you do not have an o/r H or X pipe the cats will skew the a/f readings.

With my stock tune the a/f loves to be between 13 & 13.5. I would immagine that most stock GTs are arround 13-13.5, there would be no need for the factory to run them at 10-12 a/f. That would reduce power and increase emissions. You might want to concider a wideband a/f gauge (Innovative LM-1 $350 or Dynojet Wideband Commander $500). Then you would know for sure and wouldn't have to listen to your tuners excuses. "to keep the cats from getting too hot"

raykrv6a · Nov 27, 2004

YtnGT said:
raykrv6a,
If your tuner used a tailpipe sniffer (wideband O2) and you do not have an o/r H or X pipe the cats will skew the a/f readings.

With my stock tune the a/f loves to be between 13 & 13.5. I would immagine that most stock GTs are arround 13-13.5, there would be no need for the factory to run them at 10-12 a/f. That would reduce power and increase emissions. You might want to concider a wideband a/f gauge (Innovative LM-1 $350 or Dynojet Wideband Commander $500). Then you would know for sure and wouldn't have to listen to your tuners excuses. "to keep the cats from getting too hot"

It's just the standard late model DynoJet. Really don't know how it measures AF ratio. Maybe in the calibration it compensates for the cats. Don't know.

He was really talking about the Ford tune. Lean to get the cat's fired and rich to keep the engine and cats cooler at wot. Said Ford does this for emissions at startup and to help reduce warranty claims for wot operations.
Full rich is common for engine cooling in light planes for example.

What would be the reason to get a A/F gauge once your tune is set? If I'm changing mods, I would buy an hour of dyno time and set the fuel and timing.

YtnGT · Nov 28, 2004

raykrv6a,
Your tuner is partially correct. Ford computer control systems have two basic modes of engine control open loop and closed loop. Closed loop is used whenever you are just driving around normal (not WOT). This kind of control strategy uses the factory O2 sensors to tell the computer if it is rich or lean of stoichiometric (14.7 a/f). The stock O2 sensors cannot tell how far rich or lean, just higher than 14.7 (lean) or lower than 14.7 (rich). 14.7 a/f is the ideal a/f for emissions and fuel economy. Closed loop control just maintains the ideal 14.7 a/f.

Open loop control is used for WOT... The computer knows that 14.7 is not ideal for WOT so it disregards the factory O2 sensors and goes rich (approx 13.5 a/f) based off of RPM, MAF, temp, etc...

If you have cats on your car your tuner needed to weld in a bung before the cats, per dynojets recommendations. See attached pic.

I really like having my own wideband O2 system.
-I don't trust most shops/tuners (most are morons)
-There is never a question of my a/f (gauge mounted on gauge pod)
-I can play with my tune and I always know where I am at
-I have a NX nitrous system and I definatly want to be rich!!!
-It just looks cool

XStanger · Nov 28, 2004

Last year when I dyno'd my car, my stock a/f ratio was high 10's low 11's. The dynotuner laughed and said you are running rich enough to support a couple lbs of boost!! I haven't installed my gears yet because I am going to buy a predator so I can tune the car, and compensate the speedo.

Seraphitia102 · Nov 28, 2004

What does lean mean?

YtnGT · Nov 28, 2004

Seraphitia102 said:
What does lean mean?

It (lean) is a relative term meaning more air and less fuel than someone would like.

Stoichiometric Combustion (gasoline engine) is 14.7air to 1 fuel. That is a ratio of air to fuel.

Air-Fuel Ratio (definition)
Air-Fuel Ratio is frequently used in the analysis of the combustion process. It is usually expressed on a mass basis, i.e.

AF=(mass of Air)/(mass of Fuel)

Seraphitia102 · Nov 28, 2004

so in other words: if I get the predator tuner, do i have to worry about anything?

BMan5150 · Nov 28, 2004

Very interesting post. I often wonder whether or not many tuners just say, "yeah, your car was running really rich" just to say they did something. Consider this hypethetical example:

You just install an off-road X or H pipe. Sooner or later, the MIL is tripped and the car goes into a "safe-mode" operation. When that happens, the ECU automatically richens up the a/f mixture because it's safer (less risk of pre-ignition, detonation, etc.) This is important because something within the emissions system is amiss. So you go to the local tuner with your check engine light on to get a custom tune/chip. Of course the car's running rich! You're running in "safe mode" which is already rich! Then they "tune" the car to bring it back to something more optimal for performance but not too lean so as to cause detonation/pinging. I'm not saying there isn't any value to getting a tune, but I'm just wondering if you can also accomplish an ideal a/f by simply using MIL eliminators and letting the stock ECU programming do it's thing once the MIL is off.

Thoughts?

YtnGT · Nov 28, 2004

BMan5150 said:
Very interesting post. I often wonder whether or not many tuners just say, "yeah, your car was running really rich" just to say they did something.

Thoughts?

That was my concern... There is not a tuner in my area that I would trust. You ask why, they wanted to measure my a/f after the cats. I informed them that the readings may be skewed by the cats and they responded that they do it all the time and don't have any problems... Needless to say they had four or five late model customer cars in the shop waiting for new engines. I am not saying their tuning abilities or lack there of caused the failures it is just something that got me thinking.

Why pay someone to do something you can do yourself...
Buy a wideband a/f meter
Buy a predator or even better SCT package
You will be set for quite some time...

Now that I have a wideband a/f meter I don't have to listen to any here say or BS. I KNOW FOR SURE and have the data log to prove it.

What I am trying to say is I don't like guessing. And the old "pay me now pay me later" saying applies.

Seraphitia102 said:
so in other words: if I get the predator tuner, do i have to worry about anything?

I did not have any detonation issues with the predator tune using 93 octane gas and 1 step cooler plugs. I guess it all depends on how much you worry.

WARNING!!! Predator Tune May Be LEAN...

YtnGT

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