Spark Knock.
 

My car spark knocks at really high RPM's. I noticed it doing it when I raced, but I had 87 octane in it. I thought if i just put 93 in it the car would quit knocking. The other night I raced a 96 GT and it knocked with the 93. So what could be causing this or how can i stop it?

Man, where do you get 93 octane gasoline? The best premium I can get here in CA (except at the local track) is 91.5!

I get my 93 in GA. We dont have all those d*a** laws you have out there. That is funny, I have never had anyone to tell me that they cant get 93. I havent ever heard of 91.5. The gas we get here at the track is 110 octane.

I am having the same problem but the problem with my car is only in the morning when it is cold, once the car warms up it stop the knocking. I always put 93 octane because I have a timing adjuster (the car was knocking even before I installed the timing adjuster).
HA,HA 91.5 never heard that one before.

what year car? how many miles?

what mods if any?

I've raced (On the street) several 96-98 4.6 stangs and heard them spark knock at the upper RPMs also. Wonder if its a common problem with the Pre-PI 4.6's.

Wonder if its an EGR problem, I know that can cause Spark knock. Any kinda surging going on?

ON a diffrent note. 93 ocatane in NC is readily available. Up in PA where I grew up (My dad still lives there) they have 95 Octane.

spark knock-my story
 

I'm glad someone's talking about this. Here's my story...

I have a '97 GT coupe with 70,000 miles; stock with the exception of a K&N. Over time she developed knock under load and high RPM's. I bumped up to 89 octane, then later to 93 to calm it down until I could get to the Ford guys to fix it. Once I took it to Ford they told me the octane reading in the ECM was ??? (no reading). They set it back to 85 to accept the regular unleaded gas which fixed it for about 3 weeks, then gradually, it has come back again. I am again running 93 octane keep it quiet but under high RPM's, she's still a knock-in.

Regular unleaded gas has dropped to it's lowest price I've seen here in at least 4 years. Sure would like to take advantage of it.

I was thinking of a MSD Dis-4 ignition module to get rid of the knock. Would I be better off getting a Steeda timing adjuster so I can manipulate it myself? The more simple, the better.

Suggestions would be greatly appreciated!

Thanks...

Yeah, up here in PA we have 94 octane at some places (mainly Sunoco,) but I have never seen 95. Maybe thats out in western PA?
I know at Englishtown racetrack their race fuels go up to 116 octane. And man, is that stuff expensive.
Ohh yeah, the gas station down he street from me has regular (87) for $1.01 and premium (93) for $1.17. I agree with you, these are indeed the cheapest prices I have seen in at least 4years.

Opps Typo.
 

That was a typo on my part. I ment 94 Octane. Sorry about that.

"Fixer" here are my mods....

99GT…
rear sway bar (adjustable)
rear lower control arm
traction bars,
tokiko struts illumina 5 positions
tokiko shocks illumina 5 positions
caster camber plates
racing lower springs
3:73 gears
strut tower brace
underdrive pulleys
Michelin “pilot XGT-Z4 245X17.
No silencer
No spare tire
steeda time adjuster

I would try playing with the timing.

I have contacted Ford. I am scheduled to have my car looked at this Saturday. It will have to be scanned on the Diagnostic Analyzer. They told me it could be several different problems. One could be that the injectors are not spraying as they should (which would cause my car not to be running off of all 8 cylinders). Another could be that the ECM has to be recalibrated or just completely relplaced. I will let you know what I find out when I find out.

Oh yeah, My car is a 01 and the mileage is somewhere around 7 or 8 grand. I love the prices of gas right now too. It just dropped to $.88 here and is still falling ( I wished I could take advantage of the low octane prices right now).