how do i change the a/f ratio on the predator?

[badass04mach1]

well first of all im wondering what to change everything to. i ahve done the basics with it like the axle ration and all that stuff but havjnt touched the timing and fuel stuff yet. what would i change the fuel and the spark to? my mods should be listed below to help you all. someone told me a few days ago to like rais the fuel 4 or something, but im exactly sure what that means or where to go on the predator. any help would be awesome. thanks you all.

[03 OxfordMach1]

My advice would be to find a shop that has a DynoJet, and tune your car on the dyno. If you are not familiar with the Predator I would either find someone who is, to go with you to the dyno. Or find a dyno shop that is a distributor for, and or licensed with Diablo Sport.

Be sure NOT to mess with the fuel or the spark advancement(AKA timing) without having the car on a dyno. If you do it could turn out to be a very bad day the first time you go WOT.

Once your car is on the dyno and you find out your A/F mixture, you will know if you need to add or take out fuel from either the 2k-4k range or the 4k-7k range.(The spreads that the Predator allows for addtion/subtraction of fuel) If your car is running lean then you have too much air and need to add fuel to richen up the mixture. Now if your car is running rich then you might want to take out some fuel to lean the mixture a bit. A guideline to always remember is that: Rich=Safe while Lean=Mean but not for long. If your car runs lean then you will usually make more power then if you are running rich, but if too lean you run the risk of damaging your engine. From my experience with Ford's 4V motors they seem to like a A/F around 12.5-13.0, while the 2V motors like an A/F around 13.1-13.4. I have found that the 4V motors like a little more fuel then the 2V motors. Another word of advice when working with adding/subttacting fuel is: its always better to work in SMALL increments rather than in large ones.

As for spark advancement/timing, it is hard to say, I have seen wide ranges of what cars like. I would start with 2 degrees increase in timing, as again with my experiecne, I have seen this to yeild the best gains on a fairly stock/mildly moded N/A mustang(4V or 2V). If you are running NOS then timing becomes a whole different story.

It is always better to tune your car on a dyno, as most cars react to changes differently than others. And use of a dyno is about the only "sure" way to know what exactly is going on with YOUR car verus just "copying" someone else's tune. Its good to have an idea where to start but just remember that all cars are unique and may require different changes than did others.

Sorry for the long post, and again this is just my advice. I am sure that there will be others join in on the post and either agree or disagree with my comments. Either way I can only post these remarks from my experiences as I am sure many have had different experiences than mine; or either the same. I hope that I have helped you with your question and as always Mach On!

[killer55]

With the "Mods" you have I would not change anything. If you take it to the track you might make a pass with the Diablo Tune Installed just to see if it runs any quicker. Most likely not, unless you have some good air.

The Diablo Tune advances the timing a little (approx 2 degrees) and Leans out the fuel to about 13.5. This is a vary conservative tune and don't do much for the Mach in my opinion.


Good Luck

[PapaTango]

I installed the Predator tune to my car and added an additional +3 on timing (both RPM sets) and -.05 (richer) on the fuel (again both RPM sets). I figured with my mods already installed I might be running a little lean so I decided to richen the fuel just slightly to be on the safe side. The car is definately quicker with a solid boost on the low end. Agree that a visit to a dyno shop for some fine tuning is a good idea.

[CY-Mach1]

I was able to get better results with the predator tune than the factory - primarily in the low and mid-range netting a little more on the high end.

Until you can get to dyno I would monitor your short term fuel values and look to have them average -.10. Factory mine ran -16 and with the predator tune straight -11. with an off-road h mine dropped to -6. On my car -16 produced a 12.5 A/F reading and -9 was around 13. I believe each car is different so a dyno run is the right thing to do. I data logged during a the dyno run to I could compare the collected information. To be safe I would add some fuel (+2 - +4) to componsate for the off-road pipe based on the short term fuel readings.
Use the data logging feature to monitor the timing and see if you want to modify it. Check out the other predator tuning threads for additional information.

[almach]

John,
Where did you dyno your car? I went to trackmasters on Monday and a/f ratio was way lean. I think I might have been pulling air after the MAF (leak) I've changed the setup to make sure that leaks are not an issue. If it is still high I will change back to stock for another pull but if I still run high I may want to try another dyno or just get the predator. I work in Huntsville.

Mike

[gilmoujr]

The Predator with certain chip codes has been know to cause an overly lean condition on the Mach's (mine was WAY lean). Before this race season I am going to go and get the SCT Pro Racer Package and Wide Band O2 Sensor/Datalogger. I think that it will be the best option for me since it will allow me to tune AT THE TRACK - based on current conditions.

[almach]

Talk about lean, I've been on the dyno twice this week, on monday my a/f was between 14 and 16. I went back today and changed back to the stock upper intake pipe, after the first run and the a/f is now around 13. I'm looking to go back in a couple of weeks with a predator to make it in the 12 to 13 range with the after market upper pipe. My mods were the CAI and Magnapack catbacks. I went to the stock intake pipe and I'm still running within 1 HP of the after market pipe, I'm now at 276/296, stock 272/292, huge gains for the money LOL. Any ideas other than a predator?

Mike

[CY-Mach1]

Originally Posted by almach

John,
Where did you dyno your car? I went to trackmasters on Monday and a/f ratio was way lean. I think I might have been pulling air after the MAF (leak) I've changed the setup to make sure that leaks are not an issue. If it is still high I will change back to stock for another pull but if I still run high I may want to try another dyno or just get the predator. I work in Huntsville.

Mike

Mike,

I've been working with Arthur at Trackmasters. I'm have the Comp Orange Mach that crosses your path every now and then. Shoot me a pm and we'll hook up. BTW -- mine made its best power at low 13s AFR.

John