The Dragon

iTrader: (6)

I recently installed S2 LS1 Heads with a Thunder 224 112 LSA cam (stock compression and displacement).

I was running WAAAAAAAAY lean and went back to the stock de-screened MAF ends instead of the ported ends I was running and re-set the PCM. Granted, I've only had ~5 learning miles on her after re-set so far.

I still have a super-lean condition at WOT. Popping, loses power instantly, but no registered knock <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Part throttle driving is fine, even at high rpm's eg. 4000, no problems.

I'm gonna try a vacuum leak and see if that's the problem.

Is it possible that the PCM needs more learning miles to correct the lean condition at WOT?

Again, part throttle was fine before and after the ported MAF ends.

The Dragon

iTrader: (6)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by jleews6:
<strong>Did you change the plugs and check for a bad plug wire yet? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'll check 'em when I get back from Mexico next week.

The reason why I haven't been able to do that or get to the dyno is because I fly out tomorrow afternoon for a commercial.

I made an appointment for next Sat. morning to tune this baby <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I'll check the plugs/wires next Friday night. (they only have 25K miles on them and they were NGK's TR 55's with 10.4 mm Thundervolt wires so I doubt they are the problem).

The Dragon

iTrader: (6)

With ~25 learning miles, my Lterms averaged +.94; a drastic improvement over the 12-15% I was getting before with the ported ends.

I have no idea if I logged the correct parameter but my Fuel Cell Trim averaged 18.44.

It's funny, right when I finished this log, and filled the gas tank up, I checked the log again and the Lterms were WAY negative; fluctuating between -5 and -15 <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I'll log again tonight after I put another 10 miles on her; that'll be ~35 or so miles.

<small>[ December 07, 2002, 05:00 PM: Message edited by: The Dragon ]</small>

The Dragon

iTrader: (6)

Alright. Can someone tell me if my synopsis is correct.

In autotap fuel, there are Lterm trims, Sterm trims, and a Fuel Cell Trim.

Do I average the Lterms that are only in Fuel Cell 19?

If I finally understand this correctly, than my Lterms averaged +2.26.

<small>[ December 07, 2002, 08:05 PM: Message edited by: The Dragon ]</small>

jleews6

iTrader: (2)

Did you change the plugs and check for a bad plug wire yet? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

AzzHauler

iTrader: (3)

Cell 19 is an idle cell. So you don't need to worry about that one much. 15 and 22 are used in WOT. What are your timing and o2's reading?

The Dragon

iTrader: (6)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by AzzHauler:
<strong>Cell 19 is an idle cell. So you don't need to worry about that one much. 15 and 22 are used in WOT. What are your timing and o2's reading?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I've been doing base runs for now because I cannot go WOT without popping instantly <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

Didn't know about the idle cell thing; I can list what my Lterms are without 19 at Base.

The Dragon

iTrader: (6)

I multiplied my MAF table by 110%; 50 learning miles later and I've still got popping <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
Since the install until now, I've never had popping with 0% load. I can FLOOR it in neutral sitting in the shop and no problems. This would indicate that there is no problem other than tuning, right?
Should I now use the PE table??
There was no vacuum leak, but we have to replace the timing gasket because it's not seating right. Would this be causing the problem?
I just want it safe until I get to a dyno <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

Phate

iTrader: (2)

This is what I would do...some may disagree, but I have had good results.

Put the MAF table back to stock. Use the Injector Flow Rate table to bring your part-throttle LTRIM values to -1 to -4.

After you get the LTRIMS averaging in the right range then add fuel with PE vs RPM and see if you can get the popping to go away.

Scott

The Dragon

iTrader: (6)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Scott 98Z M6:
<strong>This is what I would do...some may disagree, but I have had good results.

Put the MAF table back to stock. Use the Injector Flow Rate table to bring your part-throttle LTRIM values to -1 to -4.

After you get the LTRIMS averaging in the right range then add fuel with PE vs RPM and see if you can get the popping to go away.

Scott</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks Scott <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

If you don't mind my asking, what is your set-up?

Did you multiply the entire injector-flow rate table and PE vs RPM or did you do it from a certain range?

The Dragon

iTrader: (6)

ttt please <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Also, can I still tune with the timing gasket needing to be refitted?

It's fine when the car is running, we just saw a tiny gap when it's shut down.

Do I have to wait until we fix this?

Phate

iTrader: (2)

My setup is:

-Incon Stage I kit
-ARE Stage II heads
-Small custom cam
-38 lb/injectors

I would make the changes through the entire table by multiplying with a percentage.

I would try multiplying the entire table by 90% (making the values smaller will make the car richer...higher values in the IFR table will make you leaner).

Again, I wouldn't change PE v. RPM until the LTRIMs are right (-1 to -4). The PE v. RPM table changes are best left for a wideband dyno session so that you can see where in the RPM range the changes need to be made.

Not sure on the timing gasket question though...are you talking about the front cover?

Scott

The Dragon

iTrader: (6)

That's gotta be a wicked fast Z you have there Scott <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I was told that my gasket (front) won't affect tuning at all <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I'm gonna hit a dyno in the morning and see what's goin' on <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

Doc99SS

iTrader: (2)

Scott, Dragon has changed the MAF, put on stage II heads, etc, etc, but he still has the stock fuel system. Why would you ever tell someone to change the fuel injector table when its still the stock fuel system?????

If the MAF has been modified it will not report the correct air flow, a ported descreened MAF will always under-report the amount of air going thru it. That is why you MUST calibrate the MAF table with LS1Edit befor you do anything else for tuning.

I'm reaaaly tired of this bad advice that I see here, if the MAF was altered, then correct the MAF table!!!! How more clear can this be?

Scott, for you, you installed 38# injectors, so of course change the injector table for the assumed correct injector flow rate. For you with a non-stock fuel system, that was the right way to go, but its not for those who have ported their MAF and still running the factory fuel system.

LS1 Brent

what does WOT mean??

kick_*ss

iTrader: (1)

Man I know how you feel. After completely redoing most of my mods I don't have knocking.
It drove me nuts. Unlike you I had just bolt ons at first. SLP 85MM MAF and MAFT, SLP Airlid, SLP y-pipe, SLP 160 thermostat and ASP Pulleys. For some reason this combo made my car pop like crazy but only at WOT, if I gradually went up in RPMs it was just fine.
So since that setup really was not happy at all I went with a new setup.
FLP LTH (high flow cats and flp 3" y-pipe), TR 224/.561/112lsa CAM, REV Double springs and retainers, TR Pushrods, Taylor Spiro Wires and Split Fire Plugs. I removed the SLP MAF and MAFT and went back to the stock MAF and now I have ZERO Knock at high RPMS. I also got LS1Edit and have so far add 5% lean to the MAF table, and now its running beautiful. I did not have to mess with any of the KR tables to do anything.

I also had the NGK TR55 and tossed them after only 10k, I hit the dyno with them on and they were knocking and misfiring so bad the guy runing the dyno stopped the run and did not want me to do anymore until I replaced the plugs and wires, or find out what else was causing the KR.

and to answere the post above
WOT = Wide Open Throttle

Phate

iTrader: (2)

Doc,

There are different tools for different problems. In some tuning cases where the LTRIMs are WAY out of whack I tune using the IFR table instead of the MAF table.

Does this have the effect of bringing the LTRIMs into acceptable ranges??? In case you don't know, the answer is yes.

I have tuned several cars successfully on the dyno (Including a 2001 Z06 today...that is now making 392/380 with basic bolt-ons) and use different tools for different situations.

My tuning methods must not be too bad, my car is making 550 to the wheels on a stock shortblock and it hasn't blown up yet.

There is more then one way to do things..just because it is not the way that you do it (or perhaps you don't have the experience to do it that way) doesn't mean that it doesn't work.

Scott

<small>[ December 14, 2002, 09:14 PM: Message edited by: Scott 98Z M6 ]</small>

Doc99SS

iTrader: (2)

Scott,

Thats all well and good.

The point is: Well, I made the point above.
You dont fix whats not broken.

When you choose to change the injector table to bring the LTFTs in line, you put other things out of wack, for example the PE tables. When you lie to the PCM concerning the fuel system (when the fuel system is still stock configuration) you create several other issues that you need to fix.

If the MAF was modded or change from the factory unit, it is the MAF table that is broke not the fuel injector table. I and many others dont understand why you alter the fuel injector table, when its the MAF table that needs to be re-calibrated.

Maybe, I'm being too harsh here. Scott, what you are doing is how I tuned my '87 IROCZ, its also a MAF car. I burn Eprom chips on that car. However, I learned that I was chasing my tail on the AFR across the whole range because I was faking out the ECM about the actual fuel rating of the injectors. The fake out causes several other problems with the tuning of the engine. I learned the hard way on the '87 car. You do not lie to the computer about the fuel system, put in what you feel is the most correct injector fuel rate, and work on other tables. That is my honest experience on this matter. Sure you can tune a car to 550HP, there just is a better way to get there.

<small>[ December 15, 2002, 06:04 PM: Message edited by: Doc99SS ]</small>

Phate

iTrader: (2)

Doc,

I guess that we will have to agree to disagree.

In the case above the stock PE tables are not going to be accurate for a heads/cam combo anyway, even if you used the MAF table to bring the LTRIMs back down (assuming you could even adjust it enough to do this)...the PE tables will need to be tuned. Same thing with the IFR tables.

Anytime you make a drastic change to a car it is going to have cascading effects through the tuning. Just adjusting the MAF in this case is not going to fix his problem...just as only adjusting the IFR table is not.

I try to use all of the tools that are available. In the end it might end up not mattering which avenue you use.

As to there being a better way to get there on 550...well, quite frankly I think that is BS. My car makes 475/520 on pump gas on 4.5 psi right now. Next time at the dyno I think that I will hit the 600 barrier on a little 101 and 9 psi. How many people out there are doing that on a stock short?

I'm through stealing the thunder from Dragon's thread...suffice it to say that there is more then one way to skin a cat!

Scott

Doc99SS

iTrader: (2)

Agreed, I'm done here too.

Actually, good luck on your tuning efforts, obviously you are successful at what you do, no problem there.