First time out with the scanmaster!!

[bishir]

First my car's vitals: 87 GN mostly stock, 93 Red Armstrong chip, 93 Gas, 2.5" stainless exhaust w/ 3" cats, adjustable wastegate set at 17lbs boost.

The scanmaster instructions said 3 degrees of knock is acceptable for pump gas. Fortunately my car stays at around 2.8 most of the time when near 17lbs of boost. The fuel readings were great for a stock fuel pump and injectors at around 800-820 most of the time.

However, there are a few issues I'm having. When I let off the gas quickly after boost the knock jumps sometimes. Most of the time it jumps to 3.8-4.2, but once it jumped to 9.1 when I let off the gas quickly. I'm thinking this is normal since the car is quickly running lean for a second once I let off the gas. Is this true?

Another thing, is 3.8 too high or is on the borderline? I'm really happy with the performance so I'd hate to get too worried. I'm not looking for major modifications, but what could I do to bring down that knock number without decreasing boost. I'm sure there are many things, but I would like to start with the very simple and non invasive.

I've also noticed that the knock is easier to control if I manually shift. If I take off from a roll or start when in drive or overdrive that's when the knock readings go above normal. Do you have an idea as to why this is happening too?

Thanks for any responses,

James

 

[gnturbo]

I just got my scanmaster the other day also,I am trying to figure it out more and more.I am running the thrasher92 chip,a bosch237 reg,and a walbro340 pump.It has yet to show any knock at all with the thrasher.I am very pleased with this chip.I do not have my boost or fuel pressure gauge hooked up yet so I do not know if my boost is too low or high,I also do not know what my fuel pressure is yet ,what I do know is it has yet to knock...and that is good.

 

[viperkiler]

woah!!!!!!!

Please tell me youre not getting 4 deg of knock in 3rd gear.Youre gonna blow a head gasket. In first and 2nd gear you should only accept 1.6 to 1.9 deg. of knock but if youre reading anything in third...let off the gas quick. This is pretty simple..(if you have an adjustable wastegate)Start out small with a tank of 94 sunoco gas,17 lbs boost,and 46 lbs of fuel pressure.If you get knock turn the fuel press up a half pound at a time until no knock at wot (wide open throttle).Also make sure you dont have false knock,example...bad motormount.When you achieve no knock then your good to go.You really ultimately dont want to accept any knock at all.

 

[viperkiler]

Forgot something

By the way i forgot to say,If you have stock shifter..dont shift it. Keep it in drive unless youre cruising on the highway over 50 mph then use od. The stock setup is not supposed to be shifted.If you notice your stock shifter doesnt even lock into first.Dont start in second you will get no gain out of that.Also make sure all of your hoses are tight and no leaks,And your turbo is alighned perfectly straight with your intercooler (very important).If you still get knock then go get a quarter tank of 94 and a quarter tank of 110 and then see if you get knock.Hope i helped

 

[viperkiler]

forgot somethig else

You forgot the most impotant thing and i cant believe jack cotton didnt tell you that you NEEEED to get a hot wire kit with the walbro fuel pump.Very crucial for your application.I just dont want you to blow those head gaskets.Call cottons Hell tell you what youre missing.He gave me my whole setup.Im very very pleased.

 

[bishir]

No knock in 3rd gear.... all my knock reading either come in first or on the 1-2 shift. Thanks for the posts. I'm going to buy a Walbro pump and hotwire kit. I'm thinking my problem right now isn't fuel pressure because the scanmaster is reading about 820 at WOT. I think it's bad gas. Friday, I wasn't getting knock at the track with a full tank of 93 w/ a gallon or two of 112. BTW, the previous owner bought that setup from Cotton in Bowling Green.

Take care,

James