Why is tuning s197 required for most upgrades?
 

Alright me and a friend of mine was sitting around drinking tonight and he was telling me that I didn't need a tune for CAI's and so on. I was telling him that it was required on s197's, but i can't actually explain why. Does anybody know?

He was telling me that all I had to do was adjust my tps and it would be fine.

Drunk = no good!

The S197's EEC does a much better job at monitoring what's going on then previous computers, especially when it comes to incoming air and outgoing exhaust. While that's a good thing for stock Mustang owners, it allows them to get better performance and mileage from their cars, it poses the problem that it is very sensitive to changes, so you have to get a tune, even for simple things such as CAIs.

CAI Tune
 

You don't have to get a tune but you most likely will. The mass air flow sensor is supposed to "re-learn" the increase in air going into your throttle body but many times it wont. What this produces is a lean air to fuel ratio since so much more air is in the equation now. This is usually what causes the check engine light to go one. The tune will balance that out and you will avoid costly damage to your engine from running it too lean.

Yep they are very sensitive to changes in airflow and that's why you need a tune for many mods to those cars. Doesn't matter because a tune unlocks a shit ton of power on 05+ cars so there is no reason not to do it.

Ok so here is the last question to this. Why isn't it a way to manually fix the problem with the car running lean without using a tune? That was the actual point of me asking the question. He keeps telling me to adjust the tps and that their isn't a need to buy a tuner. I keep telling him I have to but I can't give him a real reason why.

You can't do it manually because the car uses EFI, not MFI or a carb. Those glorious days are long gone.

alright... appreciate that answer bassman

There is no TPS adjustments on newer cars, even my 2001. We used to have to adjust the TPS to correct some issues, but it doesn't work anymore. All the new cars (mine included) reset the TPS everytime you start them back to factory levels, no matter how you position them, so tell him he's an idiot, and needs to come into the 2000's. This isn't an old Fox body you're working on........lol

Wait can the '95 Mustang GT 5.0 take tunes? My check engine light wont go off either, but I don't have a CAI, I only took off the Air Ailencer, Ford Racing Spark Plugs, Wires and Royal Purple for all oils. Oh and I don't have catyalst Converters or whatever.

The lack of catalytic converters is probably what's causing your check engine light. Don't quote me, but I believe for the '95, you can't use a handheld programmer like the newer cars, you have to actually have a chip burnt for your car. No big deal, just not user adjustable like the programmers, so it has to be reburnt for changes, which leaves out the email option.

OBD-I cars don't check for cats. But you are correct in that the EEC-IV cars need to use chips to tune the cars.

I look forward to the day that we can hook our stangs up to labtops with a standard USB cable to run full system diagnostics and have full tune customization............ Who am I kidding that will never happen:(

Check out the SCT Pro Racer package, that's about as close as you can get.

By that point, the definition of ricer will be those who suck at modding 2 cylinders, and don't understand the power of a 4-banger. Also, forget the laptop, it would be to your Blackberry.

I still wish carbs were the rule of the day. I rather deal w/ fixing the mechanical problems w/ a screw driver, and not have to deal w/ $100+ sensors.

Give me EFI any day. Carbs and cool and all and my MG and motorcycle have them and I have had to rebuild both of them. But EFi makes power with good fuel economy and I'm all for that.

Yes and no. A properly set-up carb will make more power and get just as good mileage as an EFI car. The key is getting the transition from the idle to main circuits to be perfect. Also, to not use a Holley if mileage is what you want.

On the older generations this is true since you are reusing the same MAF & MAF housing, the MAF calibration does not change so the car's computer is still getting an accurate reading from the MAF no matter how large the CAI is.

But, the S197 is a different animal though because there is one other factor coming into play. The majority of the CAI on the market for these cars increase the size of the MAF housing while utilizing the stock electronics, while the older generations reused the stock MAF & housing. Since the MAF is calibrated to a certain housing diameter, it will greatly confuse your car's computer without a tune and the vehicle will go into limp mode to protect the car from what it is interpreting as a dangerously lean condition.

The exception is the few intakes on the market that are approximately the same size as the stock MAF housing. BBK and K&N are the two I can think of off hand...they are slightly larger but only by about 2-2.5%. Most cars will not require a tune for this, but occasionally a car is more sensitive then others and will trigger going into limp mode without a tune.