Is everyone running premium (92 octane minimum) fuel?

[cenok is family]

what all can change where the timing should be? does degreeing a cam affect this? what about any mods? (besides f/i etc that need less timing)?

any sort of forced induction such as turbo, supercharger, n2o, etc affects where you should set your timing. yes degreeing a cam does affect timing. any n/a car should be fine anywhere from 10* to 15*, some can go a bit higher depending on condition of the motor, any mods, etc.

 

[fastford91]

SUNOCO ULTRA 94 or Aviation fuel!! but its expensive!

 

[millhouse]

I ran 89 with 14 degrees timing, but it might make a difference that ALL gas in my state is atleast 15% ethanol. Soon i'll be running E85. That stuff is saweet.

It's only sweet if you have the compression to support it. By compression, I meing either high n/a compression or some type of forced induction. Ethenol itself is a less effecient fuel than gasoline. You will typically need around 30% more fuel in order to support the same horsepower as gasoline...and you'll need to add tons of timing in an attempt to get back to the gasoline power levels.

Don't get me wrong, it's great for certain applications...but it's not a miracle fuel.

 

[strtrcr50]

I find that hard to believe. There are some schools of thought that anything over 18 is bad for a regularly driven car, even with premium (91+). tho, like someone said before, ethanol blends are common in fuels today, so maybe the fuel you use has some ethanol in it (effectively increasing the octane rating)? Do you regularly use additives like Sea Foam?

I'm not trying to call you out or anything, but 18-20 degrees seems like it could almost be counter-productive. Keep in mind the EEC-IV will compensate for some amount of knock by retarding the ignition.Anyway, beautiful car man.

That is not true. The eec iv has no knock sensor so it can not retard timing based on knock. I wish it did. It would make it easier to tune for boost.

 

[NIKwoaC]

That is not true. The eec iv has no knock sensor so it can not retard timing based on knock. I wish it did. It would make it easier to tune for boost.

Wow, you're right. I read in the infamous "The Official Ford Mustang 5.0 Technical Reference & Performance Handbook" that the EEC-IV compensates for knock, but I was just looking at a wiring diagram and it seems the 5.0 doesn't have a knock sensor after all.

Which confuses me. Is the information in TOFM5.0TR&PH incorrect or is there another way to detect or predict engine knock with the sensors the EEC-IV uses?

So is the spark map on a stock EEC-IV "dumb" and stays constant aside from initial advance? Obviously it has different operations for different conditions (part-throttle, WOT, deceleration, start-up, etc) but will the computer make changes to the original spark map with changes in environmental factors or modifications to the engine?

This is getting into a tuning conversation- who can fill me in on this?

 

[mob]

timing at 14, I run 89. My car dosent like 87 but 93 is overkill

 

[cevtv]

87 octane here in both my 5.0 and 2003 GT


Why?

It's cheaper, and burns more efficiently anyway.

Higher octane is not "better" anyway. It's a huge myth. Different engine setups require different octane levels depending on timing, boost, tune, etc. But having a octane number that is high does not signify "higher performance".

Exactly. You should be using the lowest octane you can without detonation. More efficient and less emissions.

 

[strtrcr50]

Wow, you're right. I read in the infamous "The Official Ford Mustang 5.0 Technical Reference & Performance Handbook" that the EEC-IV compensates for knock, but I was just looking at a wiring diagram and it seems the 5.0 doesn't have a knock sensor after all.

Which confuses me. Is the information in TOFM5.0TR&PH incorrect or is there another way to detect or predict engine knock with the sensors the EEC-IV uses?

So is the spark map on a stock EEC-IV "dumb" and stays constant aside from initial advance? Obviously it has different operations for different conditions (part-throttle, WOT, deceleration, start-up, etc) but will the computer make changes to the original spark map with changes in environmental factors or modifications to the engine?

This is getting into a tuning conversation- who can fill me in on this?

I can fill you in to a degree. It's easier if you can see what the eec uses.
Download BinaryEditor by Clint Garratty and you can see every table that the eec uses for timing. There is spark control in both functions and tables. There are quite a few, but none are knock based. Mostly rpm, load, temp, etc..
Click here for BinaryEditor

 

[Shakerhood]

SUNOCO ULTRA 94 or Aviation fuel!! but its expensive!

I run 93 or 94 Octane in my 92 with the Timing set at 14, it does not like 89 Octane. I would not run AVGAS in the Mustang it has a different Vapor Pressure and will not make your car run better.

 

[Flavadave4]

Premium here is 93 octane, I use it and set my timing around 14*. I use the good stuff and could care less if it cost me $4 more to fill me tank, I don't drive the car enough to really be worried about it.

 

[talladam]

There isn't any way for the ecm to retard timing as there is no knock sensor on our cars, 87-93's.

Adam

 

[praugue]

Yeah, I have pushed the timing ahead a bit. I hand-tune until it runs the way I want it. It's probably about 15 degrees ahead or so. I'll have to check, but I do like the way they run on 92, and with advanced timing, much better.

FYI -

A quick check looks like I am at about 15° advanced. I am also at sea level to about 600 feet elevation.

 

[Redeemedsoul]

Running 94 (sunoco) on all my vehicles.
-rS