wat grade fuel should i be putting in a stock mustang....i ask this casue it sounds like my engine has a knock w/ regualr 87 octane...and from the exhaust i have deep popping sound every like 3-4 seconds

 

87 octane should be more than enough...I run 87 on my car all the time now, since I can't afford premium any more with these high *** gas prices.. . I don't get any knocking or popping from my exhaust. Even the manual states 87 octane. I have heard however that around this time, fuel quality has been degrading at the pumps, but are unsure if there is any thruth to this..

 

I have to run 93 because of my tune but bump up to 89 and run a full tank and see what you get. if nothing, go higher.

 

will do but i still have like a full tank left...so itll be a week before i can do anything

 

Might just need a injector cleaner..........or might have a bad tank of gas.......just throwing in my 2 cents

 

yea i gotta wait to see wat a new tank of 89 gas will do for my engine

 

A stock Mustang needs ONLY 87 octane.If you have engine knocks or pings then there is a problem with your engine.These can be carbon build-up in the combustion chamber,injector or a PCM malfunction,or a restriction in the exhaust.The carbon build-up can be cleaned out with fuel system cleaner or a fine mist of water sprayed into the intake system with the engine running.To keep the engine running,the MAF sensor will have to be part of the intake tube while the water is being sprayed into the engine.Be careful not to get any water on the sensor element.While we're on the MAF,make sure the sensor element is clean,you can clean this by using electrical contact cleaner.Spray just enough water mist so the engine runs rough so you will know the water mist is getting to the cylinders.Fuel system cleaner can also help with the injector problem,just drive long enough to give the cleaner time to work.Short trips won't do,several longer trips may be necessary.The exhaust restrictions are usually clogged cats.You might be able to clear the obstruction by nailing it going up an interstate on ramp and letting the engine blow the restriction out.The cats clog with carbon from normal combustion.If the engine pings don't carry it to extremes,you could bust a piston!This might also take several attempts.(what better way to spend an afternoon?)You could also use this as an excuse to purchase a new X or H pipe with high flow cats.

 

Good advice from Chopper.

But, are you getting a knock or a missfire or both? A pop evert 3-4 seconds from the exhaust sounds to me like a miss or even from running rich (which happens to sort of when you have a miss).

Add some octane boost to the current tank. If the noise goes away, then you know it is octane related. Though the root cause, might be carbon build-up.

 

Run the lowest octane gas you can without detonating. If your car isn't heavily modified, or unless it says "premium unleaded only (Cobra's and Mach 1's) then anything higher then 87 is a pure waste of money.

Grades of Gas Thread

Enjoy.

 

gay isnt it?

i dont know why people freak out over a higher fuel grade cost...if you do the math it only costs 2-5 more dollars than low grade (for 91 in colorado)

think about all the useless crap youve spent 5 bucks on...cheeseburger, a bunch condoms you didn't end up using anyways, that movie you rented that sucks, but you were bored , and wish you didnt just waste 2 hours of your life on

 

I always never waste condoms..

 

I have not used one of those in 15 years.

Back to octane, as someone already stated, you should use the lowest grade possible w/o getting knock.

Unless your car is knocking (detonation) using a higher grade will not improve performance unless the car has had the timing advanced. If you feel that the car runs better, it might just be your poacket book talking.

But, and this is a big but, older cars tend to get carbon build-up in the combustion chambers. When this happens, the volume of the combustion chamber gets a little smaller. This results in higher temps in the combustion area which results in the fuel actually igniting before spark (called pre-ignition). So in thoses cases, cleaning the chamber will decrease temps and allow you to use lower octane gas.

Keep this in mind, the term octane means "resistance to knock". The higher the octane, the more resistant to knock.

 

i have advanced timing, and so does everyone here who uses a diablo or sct tune