98Z28CobraKiller

iTrader: (17)

OK guys, I did a really long write-up of my LS2 402 install into my 98 Z28 M6 some time ago. Since then I have been working on the Speed Density tunning and I am confident that I got my VE Tables set properly and my Idle Correct. Today I went and put it on a Dynojet to compare my stock O2 sensor readings to a WBO2. Unfortunately, the shop that I went to does not have the Wideband connected to the dyno (don't ask) so I can't show the fuel curve as I did not get one. I did watch the wideband and saw that the AFR was reading like 12:1 until about 6200 and then started getting rich 11:1 to the 6800-7000RPM rev limiter that I set. I am using HPTuner software. When I took a look at the dyno sheet, I almost threw up right there on the spot even though I could tell that I was not getting the power that I should in the seat of the pants. I really expected just under 500 HP from this setup when I bought it. My problem is that there doesn't seem to be a problem with the way that the car is running. I am not throwing any codes besides the MAF code. The car is not sputtering or missing. There isn't alot of blow-by. Is there something in the tune that I may have messed with that would cost me 100 HP and 80+ torque? I am over this. PLEASE HELP ANY SUGGESTIONS ARE WELCOME AS ARE ANY QUESTIONS.

TAQuickness

iTrader: (28)

I would imagine you would find some power with a 90/90, and 1 7/8" headers, but i doubt you will find the numbers you are looking for with those mods and/or a tune.

Where you having any KR or did you try tweaking your timing while you were on the dyno?

98Z28CobraKiller

iTrader: (17)

I had some KR at the top end (like 2*). I have been told that that is normal with the 98 sensors. That should not cost me 100 hp. I have never seen a 402 under 440hp. Specially not one with stock 3.42 gears and an M6 tranny. Something is mechanically wrong or there is a setting in my tune that is f**ked in WOT.

DrkPhx

iTrader: (15)

I can't believe you're still on stock injectors. If so, what is the duty cycle? You really need a printed AFR on the dyno sheet. Also, what is the total timing at WOT?

98Z28CobraKiller

iTrader: (17)

Not sure and not sure. I will answer both of these tomorrow after I can log a bit more. I think that I overwrote the log with this info.

ninobrn99

iTrader: (8)

he beat me to it! Injectors are probably max'd out on that motor! Did you get a log of your dyno run?? (please say yes)

Ed Wright

iTrader: (1)

If it is that rich, maxed out injectors are not his problem. No more power than he is making, bigger injectors won't help a thing. Hope he finds his problem.
Btw, '98 knock sensors are not a problem if you know the software. They need to match the PCM.

That graph looks like a car detonating, or a knock retard problem.

98Z28CobraKiller

iTrader: (17)

it was pulling between 1-3* of timing from 4400 and up. Not sure if I should pull tinming out or put in some race fuel to see if it still happens and then numb my sensor some. My knock sensors are relocated so that could be picking up false Knock.

white2001s10

iTrader: (4)

Well if you know how much it pulled out, then tell us what the total was during the test.

I have to agree about the injector size not being the problem.

Do you know what your actual compression is? What size chambers?

RedHardSupra

iTrader: (1)

post your bin/logs then we'll tell you what ails you

98Z28CobraKiller

iTrader: (17)

I remember the knock retard because I looked at it while scanning during the dyno pulls and there were only 4 cells and were between 1-3* of retard. The problem is that I was so pissed after each pull, that I didn't save the log thinking that I was going to do one more pull. I made the first 2 pulls myself. On the last pull, I let the guy at the shop make the pull so that I could watch the WBO2. I did not intend it to be my last pass but I saw that I wasn't getting anywhere by changing the AFR and got frustrated and forgot to record the last pass as I wasn't in the drivers seat. Their WB was logging seperately and wasn't hooked to the dyno which sucks because I couldn't tell what it was doing at any specific RPM. I know, it was a clusterf**k.

The compression should be at about 11:1 with the flat top pistons and the 65 cc combustion chamber on the heads.

98Z28CobraKiller

iTrader: (17)

I am going to check the shortblock for mechanical problems before I do anymore driving or logging. I hope to do this this weekend and then I can get a log up.
I did verify that my narrowband O2's are close compared to the WB. What is tough is that I originally tuned the WOT AFR against 2nd gear but it was different in 4th gear. Because of my gears, a WOT 4th gear pass takes me over 130MPH and is difficult to do on the street. Not sure how to get around this.

Thanks again.

WAHUSKER

iTrader: (4)

First I'd question the a/f with those injectors. Your stokcers are only 26 lbs. I maxed my 30s (which are actually 35 on our cars) with my 9.3 CR 402 with a smaller cam and have 60s in there now with the blower. I think you need to recalibrate the WB sensor & get some 42 lbers & start over. The other thing to take into consideration is your printout is in WinPep7, so your numbers WILL be a little lower.

And I think your problem starts down around 4k. Your lines should be climbing like crazy there. I attached my NA stroker dyno sheet for comparison. (tires broke loose on 1 run) And I have an auto/stall & a Ford 9"....

98Z28CobraKiller

iTrader: (17)

I am throwing a P0121 TPS code. Could this be part of the problem?

98Z28CobraKiller

iTrader: (17)

I dasabled the TPS test as noted in the description on the HPTuners software. LTFTs all went way positive and I adjusted it. The funny thing is that know my LTFT's and STFT's are all 0. This would be ok if it wasn't for the fact that they are ALL ZERO. They were reading positive but I haven't seen one even jump into the negative for a second. Any idears?

Tech

iTrader: (1)

Yes. TPS is very important for many calculations.

98Z28CobraKiller

iTrader: (17)

I disabled the TPS test as noted in the description on the HPTuners software. LTFTs all went way positive and I adjusted it. The funny thing is that know my LTFT's and STFT's are all 0. This would be ok if it wasn't for the fact that they are ALL ZERO. They were reading positive but I haven't seen one even jump into the negative for a second. Any idears?

The car is running very smooth though. Feels a little stronger maybe 10-20 HP. It might just be because it is more responsive right now.

Tech

iTrader: (1)

Can you send me your BIN?

jason@durhamcons.com

98Z28CobraKiller

iTrader: (17)

Can you read HPTuner files?

Tech

iTrader: (1)

Yep. I have HPT.