This is a long post, so bear with me.

I A/B'd the performance of my truck (3.0 VIN engine code "V" -- FFV) with 89 octane and putting a resistor in and out of circuit. In fact, I made a potentiometer insert to dial up anything from 0 ohms to 100K ohms in the circuit.

The surprising results: no change in timing. With any resistance over about 10K to 15K my 0-60 time went DOWN. My 0-60 time WITHOUT the resistor was 10.28 seconds. WITH the resistor it was 13.05 seconds! Why?

After reading a bunch of stuff I think I have it figured out but I could use some help from "Dave and Julie" (am I speaking to Dave -- I sometimes don't know who I am addressing, lol) to find out some stuff about the FFV timing algorithm.

All sorts of Ford engines, including Focus, F-150 and others have had measureable gains from this mod. So did I, or so I thought. Here's what fooled me, I think: the FFV is automatically setting the timing up to use higher octane fuel. The FFV used to have a fuel sensor in the tank, but they don't anymore. Instead they watch things in the sensors to determine how to adjust to whatever fuel is in the vehicle and provide "optimum" performance.

This means adjusting fuel curves AND TIMING according to engine performance. From what I have read, a common algorithm for this is to use the knock sensor counts to optimize the timing. Basically, the timing starts at a "safe" value and the engine "hunts" up to the optimum timing for the fuel in use. At idle, my timing starts at about 9 degrees BTDC and slowly advances to 18 degrees after starting EVEN IF THE ENGINE IS WARMED UP ALREADY.

My guess, which I will confirm, is that if I put 87 octane in, the timing will change. I'm going to try this next time I fuel up. Then I'll try a tank of 93.

The maximum timing I'm getting is about 38 degrees during hard acceleration. However, at high RPM the timing is retarding back into the 20 to 25 degree range. I'll post a graph of a trial run later.

I want to check a graph of the same sort of run using 87 and see if the values change. It would explain why my truck is showing more off-the-line grunt with the higher octane fuel. It was not the resistor -- the truck was already adjusting the timing ANYWAY. I put in the resistor when I fueled up with the 89 -- and I believe the truck quickly adapted to the different fuel.

Now VIN "U" 3.0's and the 4.0 may not have this "timing override".

I really need someone to do this mod with a 4.0 and a 3.0 "U" code engine that can record the data somehow. Anyone out there?

For those who bought a kit of resistors from me -- if it doesn't help your truck, I'll give you your money back -- keep the resistor kit, lol! But don't panic yet -- it works on most Ford products (and many others) and it may still work for you. However the FFV is a wierd animal because it can adapt to and fuel mix from pure ethanol to pure gasoling and EVERYTHING in between WITHOUT a fuel sensor. That's quite an accomplishment and it may be an advantage. We'll see and I'll let you know.

In the meantime, Dave, if you can hit up your "sources" to confirm what I'm thinking about the FFV, that would be great.

I hate eating crow -- and I'm not chewing unlees it doesn't work on "U" code 3.0's and the 4.0, lol-- but there it is. I value honesty in these matters too much not to post this stuff.

If the fat lady sings, I'll have even more to say.

 

you made my brain hurt... thank you very much...

 

Aye, come on up here, Boyo, and I'm make something else hurt!

 

i will pass on your offer to hurt me... Mano...

 

Well, okay if you feel that way then...

 

John, this is VERY interesting. So is this to say that running 93 won't hurt the FFV mototrs as much as a U code Vulcan?

I've always heard rumors of carbon buildup from running a fuel that burned too hot, but I've also heard that the FFV was capable of using 100 octane (Ethanol).

 

Okay, here'a a graph of a test run last night.

Red=Engine speed
Green=Timing advance



Recording was begun after engine warmup, and timing is already at 18 degrees BTDC. Whenever I stop, timing drops back down to this value, and it varies under load.

Note a section where my speed never gets very high in the first nearly half the graph, then a sharp climb up to 88 or so MPH. That represents merging onto the interstate and keeping my foot to the floor.

There is an interesting feature at about 50 mph where the speed inexplicably drops, the picks back up. It occurs later as well in the "no resistor" graph. Transmission thing, or engine? Anyone have an idea?

About 2/3 to 3/4 of the way along is where I stopped the vehicle and you can see the long zero speed section. Halfway through that, notice the timing dropped to about 8 or 9 degrees and slowly rises over time. This point is where I restarted the engine after removing the resistor. BUT -- the timing creeps back up to 18 degress or so, slowly at first, then faster, as idled. When I took off on a foot-to-the-floor acceleration run, note a nearly identical timing response to the one with the resistor in place. The maximum advance (about 36 to 38 degrees), and minimum are about the same in both sections.

There is a brief spot before the secons acceleration run where I hit the accelerator pedal FAST and the timing DROPS very briefly before picking back up. It drops to -3 degrees!!! MAF mod causing rapid throttle response leanness and the knock sensor kicking in? Anyone that can explain why this happens and does it happen on on my truck? Curious. If I hit the pedal even slightly slower, it doesn't happen.

Also, notice that "hitch" in the speed but this time at 60 mph.

Finally note that when I stop at the end of the graph, the timing settles to 18 degrees at idle, just like ti did WITH the resistor. No difference that I can observe.

I stopped recording here and did 0-60 runs. The OBDGauge data collector doesn't run during 0-60 measurement because the software is using all the communications bandwidth to read speed as fast as possible. Because of my larger tires, the test actually measures 0-63 mph time -- but it still told a story.

As I mentioned previously, the 0-60 time without the resistor was BETTER than when I put the resistor back in line.

I'm open to theories, or if you have it, solid explanations.

 

I don't believe high octane gas burns hotter, it actually burns SLOWER. That translates usually into lower flame temperatures, though total final heat may not be much different. The carbon buildup is because of "quenching" of the combustion that occurs as the the still burning gases have their pressure suddenly reduced and they lose heat because of the sudden decompression.

When combustion is "interrupted", carbon that has been "cracked" out of the hydrocarbon molecules does not oxidize properly or at all. The net result is carbon monoxide and elemental carbon. The pure carbon can bind to the metal of the piston, combustion chamber, valves, etc. In all cases you want full combustion of the carbon in hydrocarbons.

So, it's not heat but the sudden LACK of it that causes carbon compounds to form in most cases. Thats why slower burning gasoline (higher octane) needs to be ignited sooner or the potential for a too-incomplete combustion at exhaust valve opening is possible.

Last, it is NOT YET DETERMINED that the FFV is actually compensating. That's my theory and I need to run tests with other fuel grades and see what it does to the timing to know. But it sure looks like it and it matches descriptions of auto-adjustment algorithms I've found in other sources -- but I have no Ford-specific data yet.

It does suggest the chips for tuning FFV engines need to be somewhat different than chips for non-FFV engines I wonder what's involved?

 

Well crap, I have had a Superchip on my 02' FFV for 2 years now, hope it isn't hurting anything.

 

Maybe not -- in fact maybe it's the same chip -- but if it is the same as the non-FFV, your truck ISN"T FFV anymore. I doubt that there's any problem -- I was just wondering out loud about what, if anything, might be different in a chip. Did you send them your VIN? If so, they may have given you a chip specifically for an FFV.

 

I don't really work in the right area to give you much more than a topical response to your problem. I will be getting some EEC-V training next month and I may gain more insight there, but I think your issue is application specific. Every engine in every configuration in every vehicle is going to have a unique strategy. And as you've found, they can be very complex. Things have advanced quite a bit over the past decade from the old lookup tables, it isn't that simple anymore. At any rate, what works to a certain degree in one application may work to another degree or not at all in a different application.

If you want to gain power electronically, I suggest you mess around with the CHT sensor. That will cause it to go into open loop and dump in more fuel. Again, I doubt it will gain you anything you can notice, but you might be able to measure it.

 

Okay, Dave, thanks. I know you have access to equipment, but wasn't sure how many brains you could tap on this. Thought it was worth a try!

I'm going to record advance and do regressions on it vs. O2, throttle position, IAT, load value, etc. and see what correlates, if anything. I put 91 (well, 50/50 89 and 93 octane) gas in it and the idle timing did not change, but the peak timing advance hits 42 degrees now, and it doesn't seem to drop as far as it did at high throttle. I need a lot more data to be sure so I'll just keep doing recordings until I either get good correlations or I give up!

 

I think you'll find, and this is just an educated guess, that the timing will only advance to a certain point, if at all, when you use higher octane fuels. It is true that the knock sensor retards timing when there is knock, but the extent to which the PCM will advance timing in the absence of it is the key question here. Since the engine was designed to run on 87, my guess is that the degree to which the PCM will advance timing will stay within the realm of expected values when running 87 octane. In other words, it never expects to have more octane than that, therefore it can't compensate for it by further advance of the timing.

You'll be able to prove this to yourself, and others, with your datalogger. Glad to see a hypothesis tested with hard data as evidence. Worth much more to the community than words alone.

 

Very true and I have thought of that (though I hope it ain't so, lol) -- but it's also possible the FFV has more range since it wasn't just designed for gasoline but ANY mix from pure gasoline to pure ethanol.

Ethanol has a higher energy output and I'm not sure of it's burn rate -- but the PCM MIGHT be programmed for a wider range on FFV vehicles due to the multi-blend fuel adaptation requirement.

 

Johnny, DON'T GIVE UP!!!! Awesome work John. Great to see someone trying to get the most of something. This is how newer better stuff comes about. The back yard mechanic at his best!!!

Keep up the good work, and countine to feel us in!!!

AWESOME, AWESOME, AWESOME!!!

 

Believe it or not, I get PAID to reverse engineer and modify equipment at work. We have lots of "one off" (company only made one) machinery that has no support anymore and I am often -- though not always -- able to keep them going and even improve them this way. The truck is just a place to continue that.

Basically, get some data, come up with some ideas, test them, proceed or change or give up -- there's a process and often it yields fruit.

Thanks for the encouragement, Adrian!!! :)

 

Alcohol has less energy than gasoline and burns slower.

Your other questions are strategy dependent, it might not change the timing at all when it is on alcohol. E85 is 102 octane so it should advance the timing somewhat, but the question is how does it know? If you could fool the PCM into thinking it was running E85 and then run 102 octane gasoline, it might make more power. Or it might not.

 

The 3.0 is rated for more HP on alcohol than gasoline. If alcohol has less energy, how is this true? Not challenging, just curious since that's what Ford says -- better performance on E85 (but lower mileage, which does square with the "lower energy").

Perhaps the "burns slower" is the reason? Fits the 102 octane equivalent you cite. Then the truck would have to be able to significantly advance the timing to accomodate it, which fits my theory.

And if may be advancing the timing (which varies a LOT so it's hard to tell) to accomodate the higher octane gas. That would explain why I felt a difference with 89, even though the resistor isn't the reason.

Also, some information reached me from Doug at Bama who says there is a timing table which has entries for different input ranges and that the IAT portion in newer trucks is zero'ed out except that above a certain intake temp it WILL retard the timing. This suggests that the IAT mod is not going to work in ANY newer Ranger, not just FFV's.

But, the "how does it know" question is the one I have, since they have eliminated the fuel sensor. If you find out that answer somehow, that would be cool to know even if it's not "useful".

 

I don't know the specific chemistry behind E85 and Gasoline (been out of the Chem loop for a couple semesters now), but in Organic we looked into the pro's and cons of E85.

E85 has a very high octane rating (96) whereas gasoline varies from pump to pump from 86-93, 102 octane being "rare".

E85 has a much lower heating value, about 12500 BTUs/lb, and gasoline carries about 18000 BTUs/lb

Gasoline had better MPG, about 20-30% more miles than E85

This is what confused me. Given the decrease in mileage, E85 was said to have slight (around 5%) power increase over gasoline, presumably due to the octane rating.

Sorry for digging up an old post, but hopefully this sheds some light on the power vs energy thing.

 

No problem. Good stuff. That's about what I was thinking it must be: apparently if you burn longer (in other words "push the pistion longer") you get more power, even if your total energy value is less.

By the way, it looks like this mod doesn't work for any 2001+ engines. Although it's still possible they "adjust" somewhat to higher octane gas as a side effect of the emission loops. I'm still investigating that.

It's really hard to measure the effect of timing changes -- the timing varies so radically at different parts of the drive cycle. I'm trying to think of a good "standard" drive cycle test that would allow me to compare different grades of gasoline and their effect, if any, on the timing. Not so easy, really.

 

The calibration is already running in open loop at high throttle openings using the factory CHT curve. Actually, the last thing you want on most Ford calibrations is to dump in more fuel at WOT. Although best power is made at about 12~12.5:1 A/F on gasoline, Ford's (and many other manufacturer's) calibrations often run as rich as 11:1 for catalytic converter temperature protection. Aftermarket calibrators often lean out open-loop fuel to bring it to optimum for power since they don't worry about cat life or high mileage emission performance. The CHT idea might possibly buy you something as a spark modifier but not as a means to provide a performance-optimized A/F mixture.

 

There is certainly less energy per unit volume with the alcohol blend but a lot more fuel per firing event. Stoichiometry for E85 is about 9.7:1 compared to 14.7:1 for pure gasoline. So, dump in about 50% more E85 and you can still get more power than gasoline with its 44% higher heating value. Any additional spark advance tolerance with the E85 is the frosting on the cake. A fuel economy comparison is whole different story, though.......

 

That looks like your 2-3 shift, John. Notice that the acceleration changes at exactly that point by the change in the slope of the velocity curve.

The 5-speed auto in your truck was developed from a four speed (which is itself a 3-speed with overdrive available in 3rd gear). An extra gear was added between the original 1st and 2nd by using 1st + overdrive.

Returning to your 5-speed, 1st shifts to the new 2nd by engaging overdrive. The shift to third is much more complex because the trans must "swap shift" the trans to the next gear while simultaneously changing your overdrive back to direct. As a result, the 2-3 shift is awkward and slow compared to the other three.

I think that is what is causing the hitch in your git-along.

 

I know about the transmission configuration, Bob -- I've lectured on it MANY times on Gen-Edge, lol. I am also aware of that funny shift between the "found" gear 2 and the "original" gear 3. Your explanation of the "hitch" makes sense. I didn't think 2-3 shift occured that high in speed though. I'll have to feel that out.

That shift used to bang in my truck pretty often until I went to Amsoil transmission fluid, then it softened up some. However, it looks to still be a problem.

I have another problem now in the driveline -- I'm about to post on it.

 

You don't think that blip was an early warning sign of your axle problem, do you?