Tried 93 Octane

[DrDusty86]

I read several places including this forum that the knock sensors are triggered early and they retard timing on my car. I hear its real common on the Zetec 2.0 from 98-03. I put 93 in my car 3 days ago, MAN, can I feel a difference. It is 106* outside if that matters. Could this be real or just placebo?
Dusty

 

[Colt45ws]

Hard to tell with out data logging before and after.

 

[cmf]

My first car was a ZX2. The knock sensor is extremely oversensitive on it. Many people, myself included, disconnected the knock sensor and had no issues. You gain a lot smoother revving in the 1k-2.5k rev range with it disconnected.

To answer your original question, I doubt it's placebo. It's well documented that this car came with a knock sensor that was too sensitive.

 

[dparm]

If anything, it may have hurt performance. I wouldn't run 93 unless the car specifically calls for it.

 

[gathermewool]

Originally Posted By: Colt45ws
Hard to tell with out data logging before and after.


+1 The only other way might be to perform a blind study. Have your wife or a buddy fillup with either 87 or 93 over the next few fillups without telling you which, and you write down your thoughts, and record MPG. The longer you can play this game, the better. If nothing else, it'll give you and your wife some quality time together at the fuel pump.

 

[Eddie]

There may be other things at play here. Normally a engine designed to run on 87 octane will not improve if running 90+ and may even run worse as Car & Driver tests demonstrated. However; if your car has been neglected and has carbon build-up that raises the compression then 90+ may indeed help.

 

[DrDusty86]

So a previous zx2 owner said it "could" have. People that don't know the engine are saying its a waiste. UUUMMMM,

I'm really confused..lol
CMF,
How do you disconnect it? Where is it? Is it on the intake?
Thanks,
Dusty

 

[ahoier]

I've heard running higher octane in an engine not spec'd for the higher test gasoline will result in un burned fuel causing carbon build up......

Which is why I think Shell adds the "extra" additive to their 93 AKI pumps

To help "break down" the possible carbon build up; and thus creates the age-old myth that higher octane = better clean

 

[MuzzleFlash40]

I'll stick with 89 octane seems to be the middle fround of all the myths. And our cars run great on it.

 

[rg200amp]

Originally Posted By: dparm
If anything, it may have hurt performance. I wouldn't run 93 unless the car specifically calls for it.


You cant lay that blanket statement out. While I agree, most cars that are designed to run on 87 will not gain much or anything, saying it will hurt the car is not true.



Originally Posted By: ahoier
I've heard running higher octane in an engine not spec'd for the higher test gasoline will result in un burned fuel causing carbon build up......

Which is why I think Shell adds the "extra" additive to their 93 AKI pumps

To help "break down" the possible carbon build up; and thus creates the age-old myth that higher octane = better clean

Higher Octane prevents preignition from compression. A spark plug will ignite 93 octane.

Shell adds extra additives because they are a part of the top tier fuel standards.

http://www.toptiergas.com/


Some cars that call for 87, like my car, can advance timing and use higher octane.

http://www.europeancarweb.com/tech/proven/epcp_1007_2010_volkwagen_jetta_proven/index.html

 

[rat]

Originally Posted By: DrDusty86
So a previous zx2 owner said it "could" have. People that don't know the engine are saying its a waiste. UUUMMMM,

I'm really confused..lol
CMF,
How do you disconnect it? Where is it? Is it on the intake?
Thanks,
Dusty


The sensor is near the oil filter on the back of the engine, look for a green plug. I have found that the easiest way to reach it is get a jack, remove the rf tire and reach in. Ford had a tsb to unplug the sensor because of it being way too sensitive, higher octane will not help. The zetec engine vibrates enough to make the sensor think there is a knock and will still pull timing. Mine ran best on 87 after unplugging the sensor.
Hope this helps.

 

[mechtech2]

Nor harm comes from using a higher octane [except your wallet].

But if it stops the knock sensor from going off [and they DO go off unnecessarily] it is worth it.
Best is to disconnect the sensor [unplug it - on the block below the manifold - under the TB facing backwards]
You should need 89 . 91 would be a rare requirement for an average stock ZX2 with their lousy computer codes.

When you put in the 93, you mixed 93 with 87, and got less.
This is a very good mod on ZX2s. Smoother and stronger powerband, for sure. Better economy often.
There is no code thrown for an unplugged KS.

 

[someguy]

On my Focus Zetec premium fuel gave the worst mpg but it ran fine. Midgrade and regular were about the same. Have you tried midgrade?

 

[mechtech2]

Unplugging the KS is a common and very good mod on Ford Zetec engines. Esp the ZX2s.
Dyno graphs show a smoother and better powerband.
Butt dynos all agree, also.
Many Hondas respond well to this mod.

But this is not a general rule for all cars. Some KS systems are OK, and don't hurt things.

 

[lexus114]

So when you guys disconnect your knock sensors, you dont get any codes, or check engine light?

 

[lexus114]

Originally Posted By: lexus114
So when you guys disconnect your knock sensors, you dont get any codes, or check engine light?



Anyone??

 

[rat]

No codes or check engine light. Its all good

 

[sciphi]

Unplugging the knock sensor might work fine on a Zetec. It'd be catastrophic to other engines, and especially something with forced induction.

 

[mechtech2]

Some cars will throw a code. A ZX2 will not . They are highly individual.
And with a turbo, I would almost never recommend disconnecting one.

 

[ffracer]

Another thing that makes an engine require higher octane is load as a percentage of the engine's capacity.

My old Ford Ranger with the 2.3L 4 cyl and full load plus a car trailer ran far better with 93 octane, but the same or slightly less smooth when empty.

I ran 87 empty load all the time. Gas mileage was about the same with 93 empty load.

Some newer cars have variable knock sensors, where the added octane gives a little more throttle response, power, and mpgs.