Sorry man i wasn't trying to insult you, i was just speed reading and saw that in bold in someones post. How many miles you got on it, if around a 100K and still original fuel filter I would get a new one and through that in, all you need is a plastic fuel line puller and its right in the frame rail, 30min TOPS.

 

I had heard the knock/octane arguements back in the 80's. I also heard that the "new" computers in the "modern" engines built in the 80's could somehow sense the octane level of the gas and advance the timing to increase performance of the engine. I was a bit sceptical at that time and still am. I do believe they can sense knock and retard the timing for crappy gas though. Could be totally wrong about this. It would be nice to know the real story. I never noticed any gas mileage increase or performance increase ever by running 93 in an engine that said 87. I did notice the 30 cent per gallon premium though.

 

yes me either...i neve noticed a mileage or performance increase..only a decrease in pinging....back then in my 4 banger i could afford 93..not now...and its not you meanv...i tried not to let him but 6686 got to me...i changed my filter recently..and its time to check the torque on the plugs..its been 20,000 miles.

 

T H I N K ! There is no way the sensors on board a modern vehicle can sense "octane level" of fuel. You'd need a properly instrumented laboratory for that.

What the on board sensors CAN sense is "spark knock", ir "ping" MUCH faster than we humans can. So the system retards the spark (or advances it) up to the limit of particular fuel you are burning that day).

I am not surprised that you noticed no difference using "premium" in an older car that is "spec'd" for regular. My recollection is the compression ratios were lower in the 80's, and if that assumption is correct, the computer and engine designers had no reason to set up a very radical spark advance curve.

By the time our V-10's were designed, the industry had figured out how to raise the compression, and advance the spark and still meet "smog specs".

So again, I am NOT surprised to learn, from what these guys are reporting, that the compression ratio of our V-10's is high enough to take advantage of premium - again, the big "IF"..is...IF the computer systems controlling spark advance are working properly.

Of course a modern engine WILL get "octane ping" IF something has gone wrong with its knock-sensor system. Of course a modern engine condition is INCAPABLE of pinging if the 1) timing is set up right AND 2) the knock sensor system IS working.

 

Hmm. I am going to assume that you are not a mechanic by this statement.
Any engine is capable of deonation, and that will include if all electronics are functioning as designed.
All you need is an accumulation of carbon and you will get detonation. You can also get detonation from a lean mix, bad EGR, a good rise in temp and a number of things.
So a perfectly running engine can develop detonation. Period.
Detonation is caused by heat and cylinder pressure and the mix ignites before its supposed to. These multiple flames collide to make the pining noise.
Back in the day we used to test knock sensors in the parking lot.
Just wrap your wrench beside the sensor and listen to the engine speed.

 

Hell, lots of things can malfunction and cause a ping. A bad MAF that causes a bad lean condition will cause pinging just due to a rise in cylinder temps.

Any part of the air/fuel system that lets you go lean will make it ping like a mariachi band.

 

If we ignore the ping issue and focus again on the mileage/performance issue for a sec-

6686l seems to be saying that 2000+ engine controlers/computers vary the timing based on the burn rate of the fuel in the tank. I can get with that. However, I am still sceptical that an engine speced to run 87 can upgrade itself and dial in new, higher performance parameters just by filling up with 93. I believe that would require a whole new set of tuning parameters dialed in by a tuning program, externally derived. In other words, the thing runs fine on 87 and runs fine, but no better, on 93, just 30 cents per more expensively. However, an engine speced to run 93 runs fine on 93, it then can reduce its' performance when fed 87 to eliminate detonation by detecting it before it can become a problem. Similarly, if you fed that 93 loving thing some 104 octane boost, all you would get is expensive exhaust and no increase in performance because the thing has no way to know its getting 104 because it has no parameters programmed in for the boost.

I leave with this analogy-

If you are getting all the vitamins your body needs in your daily food ration, and you take a Mega Vitamin C tab, where do you think that extra Vitamin C goes?

Think bright yellow liquid. AKA very expensive urine.

 

I skimmed through this pretty quick, but I read several times that this 6686L guy seems to think our magical computers advance timing until it detects ping then backs off.

Well, that is just simply NOT the case. Total timing is set to certain value max, say 32º for example, and then there are tables upon tables that will retard timing as required. Timing is pulled to reduce power for several reasons, like knock, high air intake temp, high water temp, shift points to make for smoother shifting, and list goes on and on. There are timing table specific to cold starts, and on and on.

Advance timing to some unlimited value because you put a tank of better gas in it, it does not do. That is where custom tuning comes in, and on a fairly low compression motor 9.3:1 like the V-10, the gains are not nearly as noticable as when advancing timing on a higher compression motor, say 10:1 or higher.

To much timing is also a negative when trying to make more power. There are several factors to tuning, but to keep it simple, picture a graph of HP vs. Timing. It looks like a big bell curve. Hp increases only so far with timing until it peaks, then starts to come back down again.

Back to original question, running higher octane fuel won't hurt anything, but prolonged use,should you decide to use it only, will lead to quick carbon depositing, as it is deader fuel and does not give a complete burn. Burn rates of fuels are not just a matter of octane. Some race fuels are formulated to have a faster burn rate for use in high RPM engines, like 17,000 RPM race bike engines for example.

 

Actually guys, read your owners manual. It specifically says a small amount of ping is normal: "Do not be concerned if your engine sometimes knocks lightly. However, if it knocks heaviliy under most driving conditions while you are using fuel with the reommended octane rating..... " You know the rest.

In other words, Ford says some knocking on a brand new car with perfectly functioning parts, is normal..... So much for the idea that it can't happen.

 

You need to work on those "hmmmms". And work on your mechanics skills. See...a good mechanic (as distinguished from a poor mechanic) wouldnt send a car out of the shop with the various malfunctions you described (did you know that a "lean mix...bad EGR , "good rise in temp"..are all MALFUNCTIONS ?

Work on those "hmmmms". Then get back to us. You are right about accumlations of carbon. When I started my training as a mechanic in the early 50's, we did see on older engines that were fed REALLY cheap oils, "accumulations of carbon". I suppose if you were BOUND AND DETERMINED to ruin todays motors, and could FIND a cheap enough, sub-standard enough oil, perhaps you could ruin the rings enough to pass enough of the cheap oil to get carbon build up. ANY oil that meets "mfg's specs". by definition wont produce carbon build-up in a properly operating motor (that means without the malfunctions you describe). Oh...again..."lean mix...bad EGR, "good rise in temp"....these are called MALFUNCTIONS.

I have no idea what the spark advance parameters of the Ford V-10 are. From what so many of these guys tell us, some of them ARE getting "ping" on the lower octane fuel, that goes away when they use premium. One of these guys tells us that the compression ratio of the V-10 is over 9. to 1. If that is correct, it confirms what they are experiencing is P I N G due to the failure of their on board system to retard the spark to suit the 87 fuel.

The mere fact that the Ford V-10 DOES "ping" on 87 octane (again, when the spark isnt coming back enough to stop it) confirms we can get SOME advantage out of using premium (again, if our spark advance profile advances the spark enough, which seems to be the case).

Whether that advantage off-sets the increased cost of premium fuel, is something we will have to test.

 

Hey 6686L, You don't get it.

THINK and LISTEN

There are no advance tables you speak of. Only tables to reduce timing from a maximum called for amount, or base timing.
Depending which sensor is asking for timing to be pulled, will determine how much timing is pulled. For example a shift point might call for a 10º pull, a knock might call for a 5º reduction in timing. It's all specific to which table. Kind of like if this happens do that, or if that and that happen together do this.

Let say a knock sensor table only calls for 2º or 3º of timing to be pulled below a certain RPM range then that's all you get PERIOD. If that 2º or 3º is not enough, geuss what? A slight ping! It is likely more and more timing pulled the higher you go in RPM range. A condition that causes a pinging at 2000rpm doesn't happen at 3000rpm because more timing is pulled higher up in the rpm range, or possibly more fuel added for a richer AFR. There many many variables.

When I had my '06 it would ping slightly under extreme conditions on the stock tune, which demanded an AFR like 15:1 which is leaner than stoich. When I was done tuning it, I commanded an AFR of 13:1 at WOT, and gradually allowed it to get closer to 14.7:1 as throttle and load were reduced from WOT to 90% and so on. No more pinging.

Pinging is not detonation. It leads to detonation, but there is a difference.

 

You are the one who stated, and I quote, Of course a modern engine condition is INCAPABLE of pinging if the 1) timing is set up right AND 2) the knock sensor system IS working.
And this is wrong.
Brand new motors can ping with everything set to spec.
But then you've said a lot of things I disagree with.
You go on believing this then. Hell, service writers could quote you when people bring their new rigs in that are pinging with no apparent cause!
GM paid me a lot of money for working on a problem that, according to you, doesn't exist.

 

I totally agree that he doesn't get it. But,in all fairness,there is a table for allowing the knock sensor input to advance the ignition timing if there is no spark knock detected. Now,with 87 octane-it rearely if ever gets used since the terrible OEM tunes have these things running on o2 feedback and stoich air/fuel ratios all the time.Plus,the table is limited to a very small amount of spark advance that varies from strategy to strategy.
JL

 

Shame on you for telling these nice people that...why would you want to disturb their beliefs and ruin their day ? They KNOW what they want to believe.

 

Now,to address you and what you're ranting about on here. The OEM program is setup for 87 octane,and the knock sensor(s) is(are) ONLY,and I repeat-ONLY there for a fail-safe to protect the engine from sudden load changes,substandard fuel quality,sudden increases in ambient air temp,etc. It IS NOT used for increasing performance or economy in the OEM tune. It IS NOT safe for the engine,nor is it a reliable way to tune in using the spark table(s) for max spark allowing retard when knock is detected. This WILL result in engine failure over time.
JL