Spark Knock?

[JonnyBlazeGT]

Took my car in today to have my buddy install my 3.73's. After he installed them he took it for a test drive. When he came back he said that my car has wicked bad spark knock. Asked me what I was running for fuel and I told him reg. 87 and that I was running the SCT X4 87 tune. He told me to go fill it up with 93.


SO, I did. I still had a half tank of 87. Should I be concerned at all??? I have new motorcraft platinum plugs, msd cops, and a bbk 73mm TB/Tube on the way.


Is the SCT causing the spark knock?


Also, he noticed my pcv hosed was collapsed and causing oil to blow all over the passenger side valve cover, so he replaced that.


BTW, he chirped 4th with the new gears on his test drive. Lol. It pulls a lot harder and I noticed my rpms are higher than they were but don't notice much of a difference while cruising. I guess I need to learn how to drive it right.

 

[JonnyBlazeGT]

I have a datalog file if anyone is interested. All jibberish to me.

 

[COramprat]

Mine gets bad in hot weather and that is on 93 with the 87 tune.

It's a pretty simple figure that once you put a half tank of 93 in with 87 you'll have 90 in the car now. I wouldn't worry about it. You should be OK.

 

[JonnyBlazeGT]

Well, he told me I could risk blowing my motor if I didn't fix it.

 

[Puggy_sd455]

Id try uploading the factory tune back on the ECU and see if that helps... I'm no expert on the matter but iv been wanting to get a SCT tuner myself and from what iv read the tunes they come with do mess with the ignition and give it a more aggressive timing curve witch would cause it to do that

 

[coupestang2]

Should be running 93 in your STANG anyway, anything less, I couldn't do it. Me personally, I use ONLY non-ethanol 93 in my STANG. With my engine combo, NOTHING LESS!

 

[familyman]

I am running a BAMA 87 tune in my '99 GT and I swear I hear spark knock also. In fact, before I purchased the SCT X4 with the BAMA tunes someone on this forum told me that the BAMA tunes were terrible because they caused spark knock. So I am looking for someone else to tune my car. But I will say that I tried 89 octane and didn't hear it.

 

[Deleted member 38176]

First of all, there's no such thing as "spark knock". Its called detonation. Basically, the air/fuel/compression/heat in the combustion chamber get so volatile that it ignites before the spark plug fires. Yes, this is VERY dangerous to a motor.....but not on a naturally aspirated bolt-on 2V. Do you hear what sounds like an empty can with a pebble in it being shaken on acceleration? Thats detonation. Your motor is fine where you're at. If you want, plugin your SCT and take the global spark option down 1 or 2 selections