[Guest]

Hey guys,
Can anyone help me on this one. My 92 Pulsar SSS suffers severe misfire at idle and slight acceleration when using hi-octane fuel. What is the cause of this? Spark plugs?

 

[Mike]

How high octane are we talking about? Leaded? Whats your timing set at? When is the last time you changed you plugs,cap,rotor?

Mike

 

[Guest]

Well here in Oz we run on unleaded, normally a 95 ron, but the problem started when running anything higher, up to 98 ron. The plugs were changed approx 6 months ago with platinum tips, the rotor, cap etc to my knowledge has not. The timing is at the max advance (I think 15deg)

 

[Ben]

Hmmm... higher octane burns SLOWER than lower octane does, so just using that theory your timing my be too retarded to run smoothly with that high of octane. Here in the states we say that 17 degrees is about the max you can run on 87 octane and 19 with 92-94 octane. So with 98 (almost considered race fuel here

) you may need to set your base timing higher. You can AT LEAST set it to 19 and be safe. That's what I would try.

 

[Bowlcut]

I will interject here, their octane ratings are slightly different I do believe. they are higher but arent if you understand. or that has always been my understanding. their 98 is more like our 93 or what ever. but again i could be wrong.

first thing i would do is check your timing make sure its around 15 atleast, for safety sake. then check plug wires, cap, rotor the electral stuff. then check the MAF ground, TPS voltage, and O2 sensor

 

[jacen99SE]

yea the octane numbers are different. They are using Research (RON) and we use an average of Research and whatever the other one is called (M... something, mean maybe, i dont remember)

Spark plug gap? What spark plugs, exactly, do you have? Brand and part number.

Does it happen at slight acceleration if you were already cruising at 3500 rpm or only at slight acceleration from rest?