knock retard with factory tune??

**ggino85** · 08-05-2008, 02:30 PM

ok so today i was seeing if i could take off the skip shift with my diablo predator without downloading the tune and long story short i noticed that i get knock retard (up to 2.4x) at wot, is this normal? my cars tailpipes get black ass hell within 15 miles after cleaning them too. cars a t/a m6, p&p throttle body, lid, bellows, msd wires, ngk55 plugs, and stock tune.

**0rion** · 08-05-2008, 08:06 PM

not sure exactly what you're asking about the tune but any adjustment you make to the cars pcm will have to be flashed so it would replace your factory tune if that's what you're asking.
knock is not normal. You're probably a little lean. You'd have to log the car preferably with a wideband to know for sure what your afr looks like and adjust the tune accordingly. Have you ever logged the car and do you know what your stock o2 mv's are at wot?

**ggino85** · 08-05-2008, 08:20 PM

i wasnt really asking anything about the tune, sorry i wasnt clear. i was asking more about the knock retard. why would i have it with the stock tune? dont the cars run a little rich stock? can i log the car with the predator or do i need the wideband? if so what am i logging? wat are o2 mv's? sorry about all the questions and thanks for the help.

**Fetta1** · 08-06-2008, 08:40 AM

My 00 knocks a couple of times when it is hot, after shifting and stabbing the throttle. You are going to want to get a wide band 02 kit and measure exactly what your air to fuel ratio is at all RPM's. this will allow you to see if you are too rich, on the money or lean. If you get a program (like HP tuners) to adjust some of these features, you can also take a look at the power enrichment number. They are normally set to or less than 1.0 factory and really need to be 1.3 to 1.5 to get the fuel there quicker for us that think there is a big bug that need smashed on the throttle petal.

**0rion** · 08-06-2008, 08:55 AM

Originally Posted by Fetta1

My 00 knocks a couple of times when it is hot, after shifting and stabbing the throttle. You are going to want to get a wide band 02 kit and measure exactly what your air to fuel ratio is at all RPM's. this will allow you to see if you are too rich, on the money or lean. If you get a program (like HP tuners) to adjust some of these features, you can also take a look at the power enrichment number. They are normally set to or less than 1.0 factory and really need to be 1.3 to 1.5 to get the fuel there quicker for us that think there is a big bug that need smashed on the throttle petal.

if you're talking about the pe table you understand it wrong. The pe enrichment table is a multiplier and it's 1.13 and 1.15.
stoich 14.63/1.13 = 12.94 commanded afr
stoich 14.63/1.15 = 12.74 commanded at torque peak

**0rion** · 08-06-2008, 09:03 AM

Originally Posted by ggino85

i wasnt really asking anything about the tune, sorry i wasnt clear. i was asking more about the knock retard. why would i have it with the stock tune? dont the cars run a little rich stock? can i log the car with the predator or do i need the wideband? if so what am i logging? wat are o2 mv's? sorry about all the questions and thanks for the help.

I know the predator can do real time data but I don't think you can create actual logs with it. You really need a wideband to get an accurate view of where your air fuel ratio is. Some people with stock manifolds have been known to use the stock narrowband O2 voltages (mv's) to *guestimate* where they are afr wise at wot. Although this isn't accurate it can ball park you. .880-.890 is typically what people shoot for. Lower mv's are leaner and higher mv's are richer.
Frost dropped his mail order price to $125 which is a damn good deal. I would think about maybe getting in touch with him and seeing what he can do for you. How many miles are on your stock O2's? Sooting is normally a sign of an O2 issue although it could be related to your tune.

**Khaotic** · 08-06-2008, 01:11 PM

Originally Posted by ggino85

i wasnt really asking anything about the tune, sorry i wasnt clear. i was asking more about the knock retard. why would i have it with the stock tune? dont the cars run a little rich stock? can i log the car with the predator or do i need the wideband? if so what am i logging? wat are o2 mv's? sorry about all the questions and thanks for the help.

Couple things, you talk about KR, you could be getting fuel knock to much fuel will cause knock retard also, millie volts are the signal received from your 02 sensors, readings at idle varying they should be in the 400 to 460 mv this is on your pre cat 02 and then should be in the 880mv to 920 mv druing full throttle. You want to make sure your at operating temps to get these reading. But using a wideband is best.