[ski]

Interesting read. I don't know about other S197 GT owners, but I'm thoroughly frustrated with how my car falls flat on its face when the ambient temps get into the 80's and higher. I wonder if this type of mod, properly calibrated of course, would improve both POT and WOT performance for our vehicles when the ambient temps get hotter? Have any members experimented with something like this?


http://autospeed.com/cms/title_The-5-Cent-Modification/A_110350/article.html

 

[Black Baby II]

This has been around for awhile. Back with the older 5.0's and LT1's it was a chaep trick to bypass the throttle body coolant coolant line with the thought being that the IAT would pick up the cooler temperature and tell the computer that it needed more fuel. It never in my experiance was anything that made much difference. But in concept it does make some sense. Good luck if you give it a try.

 

[travelers]

If your having a problem with the car try a new tune. Its better and safer. Even with that your only tricking the ecm. Not good.

 

[cman]

Would it be an idea to get this car on a dyno so you can see exactly what is going on with your fuel curves and timing etc, and then adjust accordingly?

 

[ski]

Thanks for the replies.

"Falls flat on its face" is perhaps a little too exaggerated of a description. But I can definitely feel a decrease in power when the temps get hot, and I'm sure that a decent % of it is caused by the PCM pulling timing in order to prevent pinging.
This article interested me because IMHO I think that Ford got a little too conservative with this hot IAT/timing pullback design, and I've been searching for a way to work around it, or at least to reduce it.
Heck, I remember that my 68 RoadRunner never pulled timing when the temps got hot, and I never heard it ping. In fact, I removed a heavy spring from its distributor's centrifugal advance weights which increased high rpm performance, and it still didn't ping.
But I also realize that it didn't have a PCM orchestrating a grand symphony of multiple sensor signals flying around at the speed of light. And that pulling on one end of this web may negatively impact other portions of the web.

I may do some experimenting with it to see what happens. If I do, then I'll be sure to post back with my findings.
In the short term, I'll probably mess around a little with the Predator to see if advancing the timing with it has any positive or negative effects.

 

[93_chargedcobra]

Back with the older 5.0's and LT1's it was a cheap trick to bypass the throttle body coolant coolant line

This resistor is just that... a trick. There is old adage that works well for tuning also its called "GIGO" Garbage IN Garbage OUT. Meaning if the quality of info into the ECM is garbage, the quality of info out will also be garbage.

The IAT would pick up the cooler temperature and tell the computer that it needed more fuel.

More importantly timing!

This has been around for awhile.

Yes and in the early days of ECM programming before we understand it like we do today. There used to be some pretty hacked up "tunes" and "tricks" to get results.

Its always best to command what you want from good information and not to trick the ECM to by giving it bad sensor data. Which is exactly what this 5 cent trick does.

 

[NCStangin]

I remember all of these "free horsepower" tricks back in my 5.0 days.
Throttle Body Coolant hose bypass, removing the vacuum hose from the fuel pressure regulator....
None of them worked.

4 low cost/free mods that did work for the 5.0's:

Ice down intake (track - then hope you stay straight so you don't run over drippings)
remove belt (track only worth .2 sec)
remove shunt plug and bump up timing (put plug back in)
remove air horn/silencer from air box (inside fenderwell this was suppose to be worth 5hp)

and maybe others I can't remember right now

 

[NCStangin]

If there's coolant supplied to an area there's probably a reason for it.
I'm thinking the problem with the 5.0 throttle body bypass deal was that exhaust crossover gas circulated through it as well and the coolant was necessary to keep it in check (EGR system issue). I would imagine at operating temperature the lack of coolant there could actually hurt performance.

I like the GIGO saying, it holds water with me.

 

[stlwagon]

I don't want the PCM adding timing because it things the temp is lower. Make engine go boom! In fact, I went the opposite route and moved my IAT sensor to the intake plenum vs the MAF. It's going to show higher temps but is far more accurate.

 

[jrowledge]

One thought, hot air is less dense than cool air. It hurts horse power, nothing can change that. Notice at the strip what kind of times are run on a hot afternoon verses a cool evening. The only way to effectively compensate is to add more air(supercharger or turbocharger), this will minimise the effect. Thing about us poor guys at 5000 ft of elevation-~10% less atmospheric pressure.

 

[tltcracing]

In fact, I went the opposite route and moved my IAT sensor to the intake plenum vs the MAF.

do you have a pic of this?

 

[stlwagon]

do you have a pic of this?

No unfortunately I do not. I'm running an IAT from a Ford Lightening. You clip two of the wires going to the MAF and run them to a new harness. The IAT is installed in the 2nd passenger side runner on the passenger side. Here's the kit. IAT Relocation Kit Intake Air Temperature Sensor & Harness Mustang (05-09)

 

[ski]

Good input from everyone.
I realize that completely eliminating the PCM's ability to pull timing when the IAT increases above a specific temperature is bad kharma due to our engines' relatively high compression ratio, and leaner than stock WOT A/F ratios. However, reducing its impact may be feasible for the following reason.
We all know that Ford was too conservative with the stock tune's torque management algorithm, which caused extremely poor throttle response and crappy driveability, and how we are able to greatly reduce this undesireable effect with more aggressive 3rd party tunes. I've loaded a 3rd party tune, and the difference in my car's throttle response is like day and night when compared to how it was with the stock tune. And that tune has been installed for 4 years without any detrimental effect on any of the drivetrain components.
Thinking along those same lines, the same may be said about Ford's software approach to the PCM pulling timing when the temps get hot. That is, it's also written too conservatively, and reducing it may also render benefits(during specific conditions).

Your thoughts?

 

[bigbensbadstang]

i know it is not what you are looking for but for a little help atleast with mine here in alabama. i am using rp purple ice and i have heard wet wetter from redline is even better.but my motor does runs cooler and performance better in the heat since i have added.

 

[KlrStng]

Since I am dealing with what I think is an intake air temp problem right now, this thread piqued my attention.

If you are running a stock tune and 85(or 87) octane fuel, you could do this and be safe if you put 91 (or 93) octane fuel in. Your timing will advance, but if the ECU detects a knock or ping, it will retard the timing and you will have even less power.

The only 2 tuning variables that will give you more power are timing and AF ratio, and both are dependent on the octane rating of the fuel because increasing either can lead to detonation and detonation=damage. The hotter your intake air, the easier your fuel burns when mixed into it, and if your timing is already advanced 25 degrees (optimal for 4.6 3v), you might start detonating. If the computer doesn't pull timing then your fuel better have a higher octane rating.

If you have a 91 or 93 tune already and you do this, I can pretty much promise you will be detonating on a hot day, and likely causing the timing to be pulled back, if you don't bend a rod first.

 

[ski]

i know it is not what you are looking for but for a little help atleast with mine here in alabama. i am using rp purple ice and i have heard wet wetter from redline is even better.but my motor does runs cooler and performance better in the heat since i have added.

Glad that it helped your car's performance in hotter weather. That's something I had not considered. Thanks.

 

[ski]

Since I am dealing with what I think is an intake air temp problem right now, this thread piqued my attention.

If you are running a stock tune and 85(or 87) octane fuel, you could do this and be safe if you put 91 (or 93) octane fuel in. Your timing will advance, but if the ECU detects a knock or ping, it will retard the timing and you will have even less power.

The only 2 tuning variables that will give you more power are timing and AF ratio, and both are dependent on the octane rating of the fuel because increasing either can lead to detonation and detonation=damage. The hotter your intake air, the easier your fuel burns when mixed into it, and if your timing is already advanced 25 degrees (optimal for 4.6 3v), you might start detonating. If the computer doesn't pull timing then your fuel better have a higher octane rating.

If you have a 91 or 93 tune already and you do this, I can pretty much promise you will be detonating on a hot day, and likely causing the timing to be pulled back, if you don't bend a rod first.

Thanks for the feedback.
Good point on using gas with an octane rating that's higher than what the tune is designed to burn. I believe that the referenced article also suggested doing this.
I also agree that the knock sensors will continue to pull timing if they detect any pinging caused by a modified IAT input signal.
However, I respectfully disagree with your comment that increasing the A/F ratio causes detonation. Actually, it helps to prevent detonation, since additional fuel reduces the combustion chamber temperatures. Conversely, leaning out the mixture can lead to detonation as it increases the combustion chamber temperatures. And one interesting fact that the article noted was the test car's A/F ratio actually enriched when the PCM went into the open loop mode under high loads at higher rpms, which can reduce the engine's tendency to ping at higher IAT's with a modified IAT input signal.

 

[ski]

KlrStng,
Delete the following from my latest post. I misread your comment.

"However, I respectfully disagree with your comment that increasing the A/F ratio causes detonation. Actually, it helps to prevent detonation, since additional fuel reduces the combustion chamber temperatures. Conversely, leaning out the mixture can lead to detonation as it increases the combustion chamber temperatures."

 

[93_chargedcobra]

We all know that Ford was too conservative with the stock tune's torque management algorithm, which caused extremely poor throttle response and crappy driveability, and how we are able to greatly reduce this undesireable effect with more aggressive 3rd party tunes.

Thinking along those same lines, the same may be said about Ford's software approach to the PCM pulling timing when the temps get hot. That is, it's also written too conservatively, and reducing it may also render benefits(during specific conditions).

Your thoughts?

You don't believe your "3rd party" tuned tweaked the amount of timing that gets pulled?

This may sound contradictory here but in my opinion (this is where we go back to GIGO) it is better to tell the ecm to allow more timing based upon a certain, but real, inlet air temp than it is to trick it and let it "think" the air charge is cooler than it really is. This way your sure your only affecting the timing and not every function in the ECM that uses IAT.

 

[travelers]

The knock sensors values can be changed in the tune. There are a few others that affect timing and AF