Spark knock

[ramichael]

I have a '93 festiva EFI 5 speed, and the thing is spark knocking i have checked the timing and it is correct, i have put 2 sets of new plugs and 2 sets of plug wires, new cap and rotor button. The only way to get it to quit is to run 93 octane gas. I have 2 questions.
1. will it hurt for it to spark knock?
2. will it hurt it ot run 93 octane gas all the time?

[yvanlavoie20]

yes

1- yes
2- yes

if engine ping ... check timing belt, then adjust timing with the sti connector grounded, verify comression and at least check egr functioning

running 94 octane on a 87 designed engine cause abnormal carbon deposit on pistons ... problem later ... cause engine pingning !!!!

how to remove carbon ??? 1- remove head and scrape pistons... too difficult 2- buy carbon remover and follow instructions, you must repeat treatement many time to remove carbon from the head of piston.

good luck

yvan

[miami man]

one time i took out the spark plugs ans squirted gumout ect on top of the pistons and let it soak in.

[Tom]

Mark exactly where it is at and then re-time it by sight until it doesn't ping.

Try one way a little and if that's not it try the other way. It will cure your problem and will not hurt a thing. plug gaps need to be at 54 or this also effects the timing, do that first.

[yvanlavoie20]

spark plug gap

spark plug gap dont change timing except if it is too large ( misfire )
i dont nkow where you found this idea....

the timing is controlled by the engine ecu but on aspire-festiva , the ecu dont have return signal from coil to alter timing... like new obd2 car :?:

timing shange if ecu have some input sensors have some change in their values ( like misfire ) but with normal spark plug gap the timing rest what ecu want.

crank the distributor without finding why the engine ping is not a repair... :?

yvan

[5.0zone]

What? I have never heard that running a higher octane would cause carbon buildup in an engine.
Why would it?

[ramichael]

I have had people tell me that it will not hurt to run 93 octane

[festivaWES]

I'm running VP110 in mine.....no carbon build up....it burns hotter and a complete burn too.

[packrat427]

I run 92 or 93 in everything I have , never had a problem .
But 93 in a low compession engine will not have a complete burn and would be considered a waste .
I thought the amazing 1.3 was almost 10 to 1 comp .
That is more than enough comp to consider 93 octane .

My Caddy is 10 to 1 and it says 92 or higher is a must.
S-10 is 10 to 1 , it has always had 93 or higher

I don't give anything a chance to carbon up :lol:

[mooseheadc]

Re: Spark knock

1. will it hurt for it to spark knock?

Your pistons&rods will not love you, and you will hate the motor when it breaks, which it will if you let it continue

2. will it hurt it ot run 93 octane gas all the time?

Your wallet will hurt.

93 burns slower, not dirtier.

However, if it is rich enough with weak spark, you can start to soot up.

you can use the old ATF thru a vacuum line trick to try to decarbon
a motor, and have even use a mist of distilled water into the
manifold to do a steam clean.

but check your base timing.

[Tom]

If your spark plugs are not set at 54 it will show as being in time with the light but it will not be because of the spark plug gap.

With your plugs properly gaped you can move the distributor timing ahead or behind until it st opes pinging and runs great.

Close to or almost pinging is best for your best gas mil age.

For power and acceleration and throttle farther from pinging is best.

Your starter needs to sound all right too or you are to far off and that is not good.

[yvanlavoie20]

timing

i have a question...

WHY FORD ENGENEERS PLACE MILLIONS OF $$$ IN TUNING ENGINE ???

advance timing is the last solution to obtain more power on a efi engine

if you advance it too much you loose the safety margin of the engine

the timing is relative to the time the fuel burn VS the piston position... do you know how it work ???


see :

Ignition Timing
It takes one or two milliseconds from the time the spark occurs until all the fuel/air mixture in the cylinder is fully alight and expanding. The spark plugs therefore need to be fired a little while before the piston reaches Top Dead Centre so as to get the fuel mixture burning at the right time to push the piston down and generate power. When measured in crank degrees rather than seconds this time delay is called ignition advance. The perfect time to trigger the spark depends again on engine speed and throttle position. Cars used to use a mechanical distributor to set the spark timing. Nowadays it is normally done by the ECU in a similar way to how the fuel mixture is controlled. The ECU stores another map on its chip of how much ignition advance is required which operates just like the fueling map. Copyright David Baker and Puma Race Engines

The amount of ignition advance required depends on the engine design. Average figures would be between about 10 crank degrees at idle to about 30 degrees at peak rpm. The required advance usually increases with rpm up to about 3,000 to 4,000 rpm and then stays fairly constant. It also needs to increase at low throttle openings and reduce again at full throttle. If the spark is fired too early (over advanced) then the mixture starts to burn too soon and tries to push the piston backwards down the way it came before it reaches TDC - very bad for power and a major cause of engine damage. If the spark is fired too late (retarded) the piston has already gone part of the way down the bore on the power stroke before the mixture is alight and much of the effectiveness of the energy released is lost.

If I had £1 for every person who thinks that more ignition advance is a good thing in its own right I'd be a rich man. Like most other things, more advance is only good if there isn't enough to start with. Excessive advance is just as detrimental to power output as insufficient advance but it's also potentially much more harmful to the engine. In fact the better the engine design the less advance is required and other things being equal, an engine that requires less advance will produce more power. Copyright David Baker and Puma Race Engines

http://www.pumaracing.co.uk/

yvan

[Tom]

Pinging is a pre-ignition knock, you have to advance the timing a little to get past this, this will be very close to factory specs.

[yvanlavoie20]

LOLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL LLL

can ping 4 ways

1- too much advance

2- too much compression

3- too much carbon

4 - ecu problem...

yvan

[5.0zone]

Most American cars are setup for 87 octane.
If you plan to run 93 octane all the time, you can advance the timing some and get a little extra power.
This has always been a popular and proven modification on Mustangs.

You are correct an engine designed to run more advance on higher octane fuel will produce more power. But this is America and if you built cars that required 90+ octane you can sure bet that most would only put 87 in and blow the engine all to pieces and then blame the manufacturer.