my 98 chevy blazer developed a spark knock a few months ago, i started running sunoco 93 and lucus octane booster and did quite up a bit, so i replaced the knock sensor and made no difference, there is no code present or stored, i know the timing is non adjustable, engine had complete tune up bout 12 months ago, i used all oem parts including ac delco plugs, any ideas on what might be the issue with this spark knock.

 

You may have carbon buildup in the cylinders creating hot spots causing the detonation.

 

Hey guys,

I have the same issue on my '98.

Suspect spark knock and have done everything (OEM plugs, distrib cap, rotor, fuel filter ) to eliminate it.

Have not yet changed out knock sensor. No OBD codes found.

Taken ERG valve and cleaned it well. Wasn't really that dirty.

Have used Techron additive and Seafoam for several tankfuls. Seafoam thru the vacuum line and soaking valves several time. No change.....Aghhhhh !!

Have no codes to on the OBD scan. Knocks start around 2000 rpm.

Causes ?? Knock sensor, carbon build-up, gremlins (haha)

Any ideas ?????

 

From another thread. The RPM mentioned jogged my memory.

 

Ok, here is new info about the 'knock'.

Driving the '98 this am, while cold, did not hear the 'knock' at around 2000 rpm as expected.

Drove it, while cold, on the same roads & at same speed at around 2000 rpm, still no 'knock'.

As engine came to operating temp, the 'knock' was present at around 2000 rpm, as expected.

Is this engine spark knock or maybe something else ???

Need your ideas and help!!!

thanks, Pops

 

hey Pops, i figured it out, why the spark knock is there at around 2000 rpm & higher, ethenol in the gas, i checked efvery possible item on my 98, final thought, i use nothing but sunoco gas & every other tank i use lucas real octane booster & the knock is under control & on top of that, the booster brings my 98 to life... if you know what i mean.