My stang immitates porky pig like WOA!

[stang09er]

unless i fillup with 93 and put octane booster in my stang... it stutters like a SOB! its very intermittent... i can sometimes floor it and ill make it a couple 1000 revs but it will then start to "miss" over and over again intermittantly! Does anybody know what i can do to stop this because buying the octane booster with every fill-up is starting to drain my pocket-book!!

i recently replaced my fuel pump with the SVT focus pump and i changed my sparkplugs about 2 months ago! the only code being thrown has to do with my off-road H pipe which has been throwing it for a long time now considering my MIL eliminators stopped working! thanks in advance if anyone can be of any help!

-very frustrated!!

 

[Jbauer]

Do you have a tuner or a chip installed?
Eiter that or you've got detonation from carbon deposits, or a bad tank of gas maybe?
I'd run some Techron injector cleaner and seafoam it and see what happens.

 

[stang09er]

well... i have filled up probly like 20-30 times (rough estimate) since i first noticed this problem. i did notice that if i used STP fuel injector cleaner that the detonation is minamal, but still present! but as soon as i fill up without the cleaner, it goes right back to stuttering like before!

 

[Stark77]

hmmmm - are the COP's/wires ok? What type of plug did you use on the replacement?

 

[Jbauer]

Ignition components have nothing to do with this.
The problem is that you are igniting the fuel before the piston reaches the combustion chamber.
And you said that it feels better when you use a fuel cleaner.
What i would do is a Seafoam treatment, normally i am against the stuff, but it has the potential to do some good here. Shove some in through the plenums vaccum line, then run some Techron injector cleaner (Not STP junk) and see what happens.
After that...i'd do a compression test.

 

[BurningRubber]

So just to make things clear, in the first post you say it is missing.

In your 2nd post you say it is detonating and missing?

Is it one or the other, or both?

If it is missing, it could be a bad coil pack, or even more than 1.

If it is pinging/detonating, it could be a timing issue.

Does the car have a tune on it? Most of them only mess with WOT timing advance, so it would be odd if it is doing it under light/moderate throttle only.


Another thing to check... this isnt common, but I have heard of it happening a few times on here. The intake manifold will crack, but not in its usual spot (around the thermostat housing). Coolant will seep down into the plug wells and cause the spark to break up.

You may want to pull your COP's and see if they are wet or moist, and see if you notice any signs of coolant seeping into the plug wells.

 

[Jbauer]

oh wait, are you missing or pinging?
or are you confusing the 2?
If all problems stop wen you use octane booster, you are pinging.

 

[stang09er]

this is great info! i am sorry for the confusion! i am not really sure if it is one or the other! i thought both had the same symptom... no combustion in that cylinder?! when i was missing before, i ran a scan on it and #6 was missing everywhere...even at idle! so that is when i replaced all of the sparkplugs and the problem was solved at idle, but still missfires at 1/2 - full throttle intermittently! i will try the seafoam... can someone explain what this process of jamming some in my intake plenums vacuum line will do (im guessing it may solve the problem, i would just like to know the science behind it!)

-also, is there an ez way to check for a bad COP!?

Thanks again!

 

[darkside03gt]

sounds like you have a bad cop.

 

[Jbauer]

Well there are 2 ways i'm aware of to check for a bad COP.
You used a scanner and it said cyl 6 was missing, so i'm guessing thats the problem.. but if you want to be very sure.. At night time, spray the coil with water, if it sparks then its broken.. sometmes this doesnt work, but it is very accurate.
The coil can also have an internal failure, or a very small crack, and you may not of seen the sparks..if this is the case, Use an OHM meter, and check the resistance of that COP. If its infinite, you know the problem.

 

[BurningRubber]

Take that number 6 coil pack and switch it to a different cylinder.

See if the scanner shows the mis-fire on the cylinder you switched the #6 coil to.

If so, that coil is causing the problem and needs to be replaced.


Missing = what you are experiencing.

Pinging/detonation is usually due to poor fuel or too much timing advance. The combustion process happens when the cylinder is still too far down in the combustion chamber to efficiently complete the firing process. It will demolish an engine if it gets too intense, especially on forced induction cars.