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Random knock under WOT?

Rodimus_Prime

Well-Known Member
So when I first got the car I couldnt do more than 5psi without getting a bunch of knock real bad. This was no doubt due to a stock chip not playing nice with all the mods the car had. Put in 42lb injectors and a TT chip and now most of it is cleared up.

Its odd sometimes I can punch it at 80mph and have zero knock the whole way up. Then a few min later I can do the exact same thing and it might show 2.3 for a few seconds then go to 0.9 and then go away. Or I might do it again and have no knock then have a few degrees pop up later.

I have zero knock out of full throttle its only under full load that I have this issue. Sadly I have no boost guage other than stock, no FPR, no wideband and my scanmaster is mostly broken. It was on the dyno a few weeks ago and very very rich like black smoke out the exhaust. The tailpipe sniffer showed lower than 10.0 AFR, I turned up the boost controller a few cranks and it seemed to somewhat help. According to the stock guage im around 18psi but no idea how close that is.

I'm sure I could throw an alky kit on it and put get rid of some or all of it but I'd rather fix the root issue, whatever that is. I'm kinda confused by the lack of consistancy. Usually in my experience with other cars knock is a extreme rich or lean/ too much timing issue. Given those things its consistant. My issue might not occur for a week and then the next week it has the problem. Its no different in cold weather or warm, just pops up at random.
 
I recommend you get a boost gage to verify the stock gage is reading right. do you mean you have no fuel pressure gage or you don't have an adjustable regulator? A mechanics fuel pressure gage would help to know what your base fuel pressure is.
I had a stock regulator that flowed 50psi because someone squeezed the housing.
 
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