Slight Knock

I am not using a power plate. My car is mostly stock with simple bolt-ons. All I want to do is tune it to it's potential as-is. If you want to know the history on this car, I'm the second owner, PO did more work to the radio than he did on this motor. I got it with the original power master (which failed and now I converted to vacuum), the original turbo (reman) is still in it and has a 3" downpipe, going out to magnaflows, 42lb injectors, applied tech cold air kit, TT chip (v5.6 at 16-18 psi, and 20/18 timing) and a hotwire kit for the pump. Car runs great; but in boost (at about 17psi) it knocks (3 degree rt). What I know now is to decrease boost, increase octane, and check fuel pressure in boost (1:1) at this point. I will do all three and report back. I think I'm just in a tuning scenario and just have to dial her in. Which seems common in these TRs.

Thanks for all the replies and help. Really appreciate it.
The power plate is just as helpful on a stock engine if not more as the stock plenum has the greatest variance in air flow between cylinders of all the upper plenums. It is one thing that I would advise you to get. I think it will provide the best chance for you to run 17 psi on 93 without any octane boosters or higher octane fuel and you should be able to do that.
 
The power plate is just as helpful on a stock engine if not more as the stock plenum has the greatest variance in air flow between cylinders of all the upper plenums. It is one thing that I would advise you to get. I think it will provide the best chance for you to run 17 psi on 93 without any octane boosters or higher octane fuel and you should be able to do that.

I concur. If you're running stock unmodified heads, intake, and upper plenum, you should be running the Power Plate. Period. Even on an otherwise completely stock car.

Outside of that combination, you need to test.
 
SteveZ28, I had been experiencing the same problem as you. Sounds like your car is set up similar to mine. I have the 5.6 TT chip, 42lb injector combo with a Scanmaster and 17lbs of boost. I was seeing KR at almost any boost level. Turns out I was running really lean. Adjusted the fuel through the chip. Helped tremendously, but still had some KR. After posting/reading on here, somebody mentioned Boostane. Bought a bottle and haven’t looked back. I have zero KR on short bursts and WOT. Did a 0-100 run with ZERO KR. Car runs great now! I also priced Xylene and Toulane. Boostane is much cheaper. I mix 1oz of Boostane per 1 gal of 93 to get around 100-102 octane. Only go through 2-3 tanks per year, but it’s a lot more fun now. There’s lots of good advice on here. Every engine responds differently. Good luck!!
 
I totally agree with the Boostane comment above. I also mix 1 ounce of Boostane per one gallon of 93 octane fuel to obtain 100 octane. I run alky as well. No knock with 24 psi of boost. I have the 6.1 TT chip with 80 lb injectors.

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SteveZ28, I had been experiencing the same problem as you. Sounds like your car is set up similar to mine. I have the 5.6 TT chip, 42lb injector combo with a Scanmaster and 17lbs of boost. I was seeing KR at almost any boost level. Turns out I was running really lean. Adjusted the fuel through the chip. Helped tremendously, but still had some KR. After posting/reading on here, somebody mentioned Boostane. Bought a bottle and haven’t looked back. I have zero KR on short bursts and WOT. Did a 0-100 run with ZERO KR. Car runs great now! I also priced Xylene and Toulane. Boostane is much cheaper. I mix 1oz of Boostane per 1 gal of 93 to get around 100-102 octane. Only go through 2-3 tanks per year, but it’s a lot more fun now. There’s lots of good advice on here. Every engine responds differently. Good luck!!

Thanks. I had 1/2 tank so put in about 1/2 can of boostane. Then it started pouring so I’ll get her out this coming weekend hopefully. I also have a power plate to put on.


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My AFR wideband shows good numbers (11-12) so curious if it's real knock or not.
to test it roll into the throttle in 3rd gear if it knocks and those knock counts build its real as your taking the drivetrain out of the equation.when the afr shows you have enough fuel,its usually an octane issue,and as the car heats up from pulls or air outside temps you will get ghost knock,especially with the stock intercooler and turbo.check motor mounts, downpipe,etc.but you need 0 knock.
 
Stock turbo with 3in downpipe
16-17 psi
Turbo Tweak chip (5.6, 42# STREET 93 - 20/18 degrees - 16-18 psi)
rjc plate,and you should be looking at fuel pressure to see how the pump is doing,get the injectors cleaned if they are not new.personally i would never really on pure pump gas and push over 15psi on stock stuff,i have done it before but learned that that fuel is not always consistant.adding to that the stock intercooler doesnt control air intake charges very well,and the stock turbo builds alot of heat in the boost areas your running.you would be smart to have octane in whatever form you wish
 
Ok so I took her out today with some boostane added to the 93 I had in there. I used about 1/4 can. Ran great all day with no knock at all. Filled the tank to capacity with 93 and added another 1/2 of the boostane. Still ran good but got 1.2 degree knock at 16psi. I looked at the back of the can and I probably have about 3/4 can of boostane and a full tank now which would bring me maybe up into the 98 octane area. How much boostane are you all running? I have an rjc plate to put on and fuel pressure is solid.

One weird thing is I wanted to test my ac since we charged it last year. Pump kicked in but no cold air. When I turned the ac off, car acted like it was gonna die. I put it in gear and then back to park and idle seemed a bit weird with scanmaster showing o2 mv in the high 600s. Took it around the block and now it’s all back to normal.

One more question. Is it normal for the o2 mvs to bounce around a lot under normal driving? Car ran so smooth but noticed the SM going all over the place from really low to the 800s, some times the 2,3,400 range too but only briefly. My wideband showed 13.5 at red lights and in the 10s getting into boost.


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There is a mixing formula on the back of the can, always add more because pump 93 ain't really 93 anymore.

Cheapest way out is to invest in an alky kit , 20 cans in and your approaching the price of the alk kit anyway..

but only if octane is your problem ;)
 
I wait until I have a quarter tank left and put in 10oz of Boostane and 10 gallons of 93. Before I did the first dig run, I did all of my “tuning” in third gear. Put the shifter in “D” not overdrive, get up to about 35-40mph and jump on it. Sometimes KR will appear on the scanmaster at first, but it goes away almost instantly. So that tells me it’s driveline related and not real knock. I would really like to get an alky kit, but I don’t drive the car all that often (2-3 tanks a year maybe). But who knows I may pull the trigger one day :)
 
So that tells me it’s driveline related and not real knock.
sometimes that is right as long as afr is correct and timing is reasonable for the fuel being used.finding the knock issue even if its drivetrain related should be addressed,as any knock is bad or will slow the car down from timing retard
 
There is a mixing formula on the back of the can, always add more because pump 93 ain't really 93 anymore.
mixing sucks these days,and is troublesome at best.its a tuning nightmare and even bigger one if your trying to be reliable
 
mixing sucks these days,and is troublesome at best.its a tuning nightmare and even bigger one if your trying to be reliable
Race gas eats 02 sensors alive...not sure how I know that.;) Now, how tough is Boostane on sensors.
 
Race gas eats 02 sensors alive...not sure how I know that.;) Now, how tough is Boostane on sensors.
the newer sensors are supposed to be more race gas friendly,i have seen plugs off the boostane thats a whole different thread:rolleyes:the leaded fuel loved coating the sensors when i ran it lol.
 
the newer sensors are supposed to be more race gas friendly,i have seen plugs off the boostane thats a whole different thread:rolleyes:the leaded fuel loved coating the sensors when i ran it lol.
I'd go through 3 Densos a season...but I was out every weekend. Thanks for the insight. :)
 
Thanks to all the replies. Yes, I was doing my “testing” in 3rd gear and got knock that went away. My wideband was showing 10-11 afr too.

The SM as a tuning tool isn’t all that great in my opinion. It’s slow. I think it’s great for monitoring but for tuning a power logger is best. But I’m only working with what I have.

Thanks for all the help.


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