need to kill my KR

[Firestorm]

here it is, my '03 sss was mail order tuned by one of this sites supported vendors 4 years ago.

i have a 06 cobaltss s/c as a beater, which wound up going to the track and needing a lot of tuning.

hence i bought hpt pro and an LM-1 afr. tthe truck has the formentioned tune, and a gmpp intake, and a corsa sport.

pretty tame IMHO.

now the wife nagged me to log it one day, and omfg, kr up the wazoo. ive never heard it, and it's mainly her ride, so hear no evil, see no evil.

mind you it is only under WOT between 3200-6500 rpm. i run 91 always, and the odd tank of 94, which yeilds lesser mileage.

i havent got around to welding my spare bung yet, so i use my tail sniffer on it. i have already added fuel to about stock levels at WOT, and am putting a 160 stat in tomorrow. i have my file prepped for fan changes, and am wondering what is a nice afr target to hit. i am going to pull timing, but want to keep as much as possible of coarse. i am used to my rich as hell cobalt and know the truck will lean out a lot more safely, so I'm asking the noob Q of the day.

p.s. the truck is doing holidays in the mountains next week, so I am kinda in a hurry. please and thank you.

 

[Badkarma]

Less mileage with 94? Thats odd I have always had the opposit with higher octain gas. What part of the country are you in? I know out here in cali they us alot of Alky as a cheap way to boost octain. I found out the hard way when it ate up my custom carb. Point being that more than likly your not really getting 91. I have never been much for additives, but try a bottle of that Lucas octain booster in the red bottle. My truck loves the stuff. I spoke to them directly and asked them how much it would bump up my 91. the lady I spoke to said it would take it up to 98. Im sceptical of that, but both my truck and camaro* that I normaly run VP100 in* tend to like the stuff.

[.justin.]

I suspect I know what the cause is. PM me with the name of your previous tuner and if it's who I suspect, I'll give you a nice quick fix for it.

[Firestorm]

i am in edmonton canada, and there are 3 stations with ethenol blend 94. for the whole northern province. as a rule we have also run 1 bottle stp octane boost to help the truck attain better mileage , and e add 2 bottles for hwy trips. the closest station is 20 miles from me, so we goto the esso on the corner for gas. well, mu cobalt is tuned for 94 only, so im committed for that car. what a pain.

the ethanol has more octane, but less btu's i think. i get way better mileage in the car before i had no choice but goto 94. thk god my meth kit is almost in. maybe i should get snow for the truck, but the wife kinda only wants one modded car, and a pretty stock one.

but back to my original question, what is a "aggressively safe" AFR @ WOT.

[.justin.]

but back to my original question, what is a "aggressively safe" AFR @ WOT.

 

Anything in the 11.5:1 - 13:1 range will yield close to the same power (chpspecial and 12'srock can confirm this). More fuel = better thermal protection.

[Firestorm]

great stuff. ignore your pm, justin i threw the fuel up to stock WOT levels to start, until i could gather more info.

[chpspecial]

Anything in the 11.5:1 - 13:1 range will yield close to the same power (chpspecial and 12'srock can confirm this). More fuel = better thermal protection.

 

Yup this is true, and dyno confirmed. 12'srock's truck likes to run at the 12.5, so I would say that would be a good spot for you to start at. I run 11.3 in mine with the turbo, so that would be good for your cobalt too.

[Black2003SS]

I have the same issue with my truck...have 6-8* of KR. My only furhter mods are pace setter headers and 2600 stall converter...I dont hear my KR either. Always happens in the upper rpm range...replaced pretty much everything I can think of...it must be false knock from somewhere...who knows...let us know what you find out.

 

Thanks.

[Firestorm]

unfortunately the cobalt is at 10.5 but leans out to 11.5 above 7k, but gm says #4 will blow as its last in line to get fuel ,

and first to get air, go figure. im trying to keep it under 11.

cant wait for my snow performance meth kit to show up to keep it in check, its running 15 lbs boost.

 

 

the trucks stock plug gap is .040 i believe, waht do you think about going to .035 to help the burn?

Edited July 15, 2007 by Firestorm (see edit history)

[chpspecial]

Also, to find out if you have false knock or not, try running the motor on race gas. 101+, if you have the same amount of knock in the same areas then your picking up something else or its just false knock. If the knock goes away then it might not be false and you should try removing a few degrees of timing in the affected area of your timming table.

[Firestorm]

i could try that after holidays. but for now, here are my results, i put in my hypertech 160 stat.

have a look at these and comment please. afr was sniffed at the tail-pipe.

here was before:

after some playing, i got to this:

 

any constructive critisism? thx for the input yawwlll.

[thallent]

I have basically the same high octane table that you have so i am assuming that we have the same tune. I also have cai and catback. I had the same tune on my 03 and the 04. The iat of 114 might have a little to do with it seems a little warm. You might want to try playing with the iat spark advance correction -add table. remove some timing there according to the intake temp and move your high octane table back to what it was. it seems that the high octane table setup that way works for me in the 70* range for intake air temp and I am running 93 with stock stat.

Edited July 16, 2007 by thallent (see edit history)

[Firestorm]

it a little warm yah. this unit never races anyone at anytime, not even the track.

start and stop traffic, and soon holidays in the mountains, i expect IAT to always be kinda high.

my billet grille is getting in the way of airflow as well.

i found this am going to work, that when im calmly cruising, then punch it, i still get some kr, about half what i was, in a higher range 4-6k, but from a stop then WOT like i was racing, there is no kr.

my enrichment rate is .0303, and my PE delay is set at stock 5500 rpm.

am i crazy thinking i need to crank up the computers ability to compute faster, via the enrichment rate.

its set at .05 in my car, and i saw someone here advise someone else to set that at 1.0.

can it be? and maybe dropping the pe delay a bit, to say 3500?

and my add vs. IAT is zero's across the board.

[12'SROCK]

Anything in the 11.5:1 - 13:1 range will yield close to the same power (chpspecial and 12'srock can confirm this). More fuel = better thermal protection.

aint thet the damn truth when dyno tuning my truck wed did all the AFRs from 12.1:1-12.8:1 and there was no HP or TQ gains

[zippy]

I personally shoot for around 12.2 to 12.5:1 if I'm tuning with a wideband on a naturally asperated engine.