carguycw

Just checked the manual. The FP-DE does not have a knock sensor. Neither does the 99-00 ZM-DE (although it turns out that the 01 version doesn't either)

Sil_Pro5

dude, unless you read inside the gas cover (on or around the gas cap), or in the manual that Mazda says, "Premium Fuel Recommended", then dont!

the ONLY time premium fuel is required is when an engine needs higher knock resistance because of either, high compression, advanced timing, etc...

If the ECU is programmed for premium then you had better use it. otehrwise, if the ECU is programmed like the Pro5's, and it wants regular, then use regular.

however, if you ever notice a "pinging" whilst driving, esp. under load, then use a higher octane rating each time unitl the "pinging" goes away. that pinging is knock. but remember, you can have knock and still not hear it until its too late. then its KA-BOOM! for your engine.

i know its hard to resist the urge when youre a "newbie" (i used to be one also) but, trust us-its cool to ask these sorts of ?'s. hey, thats what this board's here for-right?

Sir Nuke

it sounds like a loud RATTLEING....like all your valves are about to come loose and shoot through somehting.

LinuxRacr

I own an MP3, and it has knock sensors. It also has advanced timing. That is why i recomends that we (MP3 owners) use 92 and above octane gasoline. I have the FS-ZE engine in mine, so it is a must with the higher compresion. I stick to 93 octane.

carguycw

I don't mean to prolong this thread much more (it's already pretty darned long ) but just because a car has a knock sensor doesn't mean that it will automatically benefit from higher octane. Most cars with knock sensors will not advance the timing more than a preset amount, no matter what. This is to prevent the knock sensor from triggering unnecessarily, because retarding the timing at full-throttle, high-load conditions will sometimes INCREASE knock by increasing combustion-chamber heat.

The only way to know for sure if an MP3 will REALLY benefit from higher octane is to test one with varying fuel octanes, hook up a computer to monitor the OBDII system and see when the knock sensor triggers. If it won't trigger on 89 octane, there's no reason to use 93.

I see that you live in Arlington, Texas. I live in Dallas, and Edwin (TheMAN) lives in Garland and owns a laptop with really trick OBDII monitoring software. If you want, we can fill your car up with 89 octane, hook up the computer, and do some full-throttle 3rd-gear, uphill tests in 100 degree weather and settle this once and for all

BTW the MP3 has the same compression ratio as the regular FS-ZE in the ES/P5, which has almost the same compression as the FP-DE. I don't remember the exact numbers for each engine, but it's pretty low (8.x:1).

PJStyles

My wife owns a '95 Honda Civic LX and when we park the car and turn the ignition off.. we here pinging all the time... is that the kind of pinging you guys are referring to?

Many years ago... 1997... I owned a Hyundai Elantra SE that did the same thing... just want to make sure my wife's car isn't going to have some problems... and was wondering if this pinging we hear after the car is shut off is a symptom of anything.

PJStyles

PJStyles

Pardon my stupidity.. what is FS-DE?

PJStyles

Sir Nuke

its the engine designator.....

and as far as you hearing pinging when you turned to engine OFF....ahhhh we are talking about two different things here I think.....what YOU are refering to I believe is it sounds like the engine is still TRYING to run? commonly refered to deiseling...and then it finally dies. I had a car once that did that so bad that it seemed the only way to get it to finally stop was hold the brake down good and hard and let out the clutch! lol it was a POS anyway.

PJStyles

Sir Nuke,

I don't think you understood what I was describing.. the car is already off and in the muffler somewhere, I'm assuming, you hear a pinging as if there is gas dripping onto the bottom of the muffler or something... dunno... hard to describe but I've heard it on many cars just never really knew what it is.

PJStyles

RaT

Hey PJ,

The sound you are talking about is your exhaust system cooling off.

If the sound is like a ping it's ok, it's just cooling off. If it's a loud crack or snap sound you could have a cracked manifold and the car should be serviced.



I am also wondering what engine knock sounds like. I find my pro runs rough at first until you drive for a while. I wonder if this rough sound is knock. ???

Can someone please describe what "engine knock" sounds like. I'm not sure I buy the previous description of it sounding like the engine flying appart. (if that's how it sounds I'm sorry, I just doubt it as I've NEVER heard that in any engine no matter what gas I put in it)

carguycw

Yes. D'oh!

The FS-ZE is the 170 hp JDM Sport 20 motor, which DOES have higher compression (10.5:1). The FS-DE is the motor in the ES, P5 and MP3.

carguycw

It an irregular "tick...tick-tick.....tick" sound that sounds like someone tapping two of their rings together (best description I can think of).

The best way to hear it is to stand next to a diesel engine. Diesels ping constantly because they are compression-ignition engines and they ignite their fuel this way rather than using a spark. When a gasoline-fueled, spark-ignition engine "pings", it basically sounds like a diesel for a few seconds at a time

carguycw

The sound you're hearing is small explosions inside the combustion chamber. It is not the valves slapping shut because it happens during the power stroke when all the valves are fully closed.