BattleShip

How did you verify it is false knock? You often pick up power leaning a motor out, BUT lean motors seldom last long. I often believe it is false knock like an LT1 almost always knocka ~4000 rpm.

I leave the knock sensors in with open headers, twin turbo's, roller rockers I have never had to tune around a false knock. I know it is tempting but it is also expensive if the engine does knock.

I don't use LT4 km either, my $.02 enable the knock sensors.

Good luck

Michigan Skip

OK, I don't feel so bad then. I do think I have a problem with the tranny though, on that 13.12 run, I had an 8.29 eigth mile ET which converts to a 12.94 quarter mile ET using this

http://www.empirenet.com/pkelley2/eight-to-quarter.htm

So I'm thinking maybe It quits pulling somewhere down track.

BattleShip

How rich was your tune? How did you determine you are rich?

The formula I was given is

1/8 * 1.5832 = 1/4 is 13.12 for your track time

Which is dead on your number. Therefore, I do not see a problem from the time with your transmission. And if you want to know why there are differences in calculators here is a read

http://www.stealth316.com/2-calc-hp-et-mph.htm

Michigan Skip

If you check the stock tune on an LT1,( at least the two I have) you'll find that when running in PE mode, that the PCM is fueling for a target AFR of 11.80-11.99, OR 11.08-11.95( Depending on wwhether you're using Jody Shapiro's or Andrew Mattei's formula) in the 4800-5600 rpm range. I leaned the AFR out back to 12.6 in that rpm range.
I verified that it was false, by running Torco Accelerator mixed at 104 octane, plus studying numerous Datamaster logs plus pulling the plugs and checking them. Hope that explained my reasoning for what I did

BattleShip

My question is how did you determine and then verify the AFR is 12.6?

Michigan Skip

That's a fair enough question. I have an excel spreadsheet that I use to calculate the numbers I need to plug into the AFR tables to get the AFR I'd like to have, then I use this little gadget

http://www.widebandcommander.com/

Surprisingly enough, the logged AFR is really close to what the PCM is commanded from the tables.

Michigan Skip

Yeah, the calculators I've found use 1/8th * 1.56, so I guess maybe my tranny is ok. That's good

BattleShip

I have had similiar experiences it is amazing how well this stock system works. I didn't want to explain to much because then your answer might have been biased. I do similiar, do you find your narrowband O2's are stable ie read consistent mv compared to your wideband?

What RPM are you trapping at? Since I read you don't shift into fourth, there is a technique I always wanted to try, but never had the need. With a 'good' torque convertor and transgo transmission kit you can lock the torque convertor in any gear (I don't have tuner cat here but I think 2, 3 and 4 might be just 3 and 4) at WOT.

I have NEVER tried it, BUT in your case it could give you say a 200 - 300 RPM 'upshift' to lunge your car at the end of 1/4 mile. I talked to a guy at a drag strip in Florida a couple years ago that used it and claimed it helped him and as I recall he claimed to do it in 2 and 3, but since it has been so long I can't be sure.

Might be worth looking into if your RPMs are above your sweet spot.

Good luck

Michigan Skip

I'll get back to ya, I have to go earn some money. Good talking to someone who isn't cut/paste opinionated.

Michigan Skip

I lost a lot of logs when my hard drive crashed last winter. I went back to look and can't find them. I did log about 30 minutes of highway driving with Datamaster and my wide band though last saturday. Part throttle driving logs show my narrow band sensors toggling red/green/red/green and between 125 and 135 on the short terms and the O2's running between 250- and 850 both sides. The wideband toggles back and forth between 14.5 and 15.0 just not as fast as the oem sensors do. I will say though that running WOT, as I understand how the GM PCM works, the PCM goes into a "sort of" open loop mode where it used the PE tables to determine fueling and not the O2 sensors. I will say, that I do remember some of my WOT logs with Datamaster showed the O2's showed somewhere around 800-900 mv at wide open throttle. Keep in mind that these o2 sensors have about 60K miles on them. But to answer your question, it looks like they may be following each other. The narrow bands swing between their full range and the wideband is toggling in a narrow range of AFR that would seem to match that of the narrow bands.

Michigan Skip

I know a few guys that do lock the converter like you say, I haven't gotten around to that just yet as I'm still not fully up to speed on the trans tables yet. All I've done is do away with the "limp home" scenario, and adjusted the shift points.

BattleShip

My experience has been similiar right down to the wideband being slower. I think datamaster is a steal and it has paid for itself in gas savings and finding problems many times over as well as knowing more what is occurring.

Correct you can use this data from O2 to focus on rpm range that has a problem. usually within an RPM range fueling is 'stable'. GM does good work I would love every 100 RPM but probably would change nothing simply make it more complex.

Yes wot should be ~880 NA boosted >920+ if your O2's are ok. There have always been disputes on whether they can be trusted...better to use wideband but that is in a perfect world. I still trust the O2 to indicate a problem, and in boosted we tend to run rich anyway since we lose hp for being rich but not much. NA is different story

That has been my experience. I have old O2s and they are fine for even wot. My tow vehicle is a Roadmaster with 9 psi it pulls like a train towing and scoots for the weight.

Well nice chatting I am worn out from a few on here..I had heard it was better but that is life. I am amazed there isn't more policing of the obvious I think, I feel, I believe non sense where people claim 20 from a tune, 10 from this 20 from that and then you find they have never been to a dyno and no one points it out.

Good luck with your setup, I already see why most no longer post here it is simply too much trouble.