ok so here is another screenshot from the editor under engine>tq mgt>general I think this is where the retard starts upon the down shift I've been under the impression that the tq mgt that is normally tuned out was all under the trans tab. Do I need to adjust some of these tables? When I down shift the low trac light comes on if I'm not on the gas and brake hard enough on the brake to unlock the converter and on the gas to get the rpms up so it doesn't get a downshift scratch

 

You see how the timing in high airflow regions goes from around 28 to 27 then up to 29 as rpm climbs? before messing with any other tables, I would reduce timing here so that the entire area is still smooth, but instead if moves from 24 to 23 then up to 25. The whole region should lose about 4* of timing for purpose of diagnosis.

Then see if anything changes with the knock retard, if it stays on the downshift but drops out during the long gear for example like we suspect it should if the downshift retard is false knock.

Hopefully someone can chime in about the other graphs you posted, I am unfamiliar with that particular feature in the software you are using ( I never played with HP tuners yet ). If you had a dyno our reduced timing graph could be matched up with a dyno output for better diagnosis, i.e. the reduced timing values will give less or NO knock retard and torque output will remain very similar +/- 2~ rwtq shows us that the additional advance was unnecessary.

 

k dyno isn't in the cards right now, I'm going to do as suggested with timing and go from there
thanks

 

Do you have an egt gauge? You dont need one but if you happened to have it, I could give you some insight to using it correctly.

 

no, I don't have one

 

i have a 1998 too and am battling some KR too. Mine is manual trans, no traction control, aftermarket cam and headers.
Local shop replaced the knock sensors but I don't know brand. They "work" as there is KR but I don't know what brand they are. A bunch of screen shots you might find interesting in my thread.

When i first started, it was getting up to 4 degrees KR but now only getting less than 2 degrees, in 2 spots:
-after WOT in 3rd, off gas to shift, as going back to WOT in 4th, getting KR during this transition.
-some small KR in the middle of 3rd about 4k rpm but goes away quick.

my thread here:

https://ls1tech.com/forums/pcm-diagn...e-bad-pcm.html

Your timing looks too high and I would richen it up a little to be mid-12's. These are the changes I made, usually one at a time:

1. changed the knock sensitivity from stock 1998 to stock 2004 z06. "knock sensor level vs. RPM vs. Cyl"
2. decay rate table to .25, knock retard decay
3. the Cold Power Enrich Enable TPS Threshold vs. RPM. Back to stock (although i'm going to make this more aggressive this weekend to see if it helps with the transitioning KR i'm seeing going into 4th)
4. Lowered the timing in lower the RPMS. Copied stock z06
5. Knock Sensor Level vs. Tip In TPS, levels increased to be less sensitive during shifts; copied from stock z06 (although I might increase it even further this weekend)
6. copied high octane to low octane, smooth function to MAF table, changed MAF Airmass Filter to 0. 0898 (same as z06).
7. changed burst KR to zero (but didn't notice any change when i did this).

So this weekend i'm going to try:
-increasing PE table to richen mixture from current about 12.7 across the board and change that to richen to 12.3 between 2000 and 4800RPM, keeping everything else the same (12.7)
-going more aggressive when going to PE; I think I will make it reference PE table at 10% TPS to help with that transition issue rolling on the throttle in 4th

 

ok so how does timing affect afr? and I know I'm gonna get a bunch of "it doesn't" but when I pull timing my afr goes lean. now to anyone who says it doesn't affect afr. prove it with data becuz all I see is it going lean when timing is reduced. my afr err in pe sky rocketed when I pulled timing.

I know I prolly sound like an idiot but I'm just trying to learn something here lol s

thanks guys

 

on another note down around 20deg I wasn't getting any knock

 

At this point, you will want to inspect the pcv system if you have not recently, and check the plugs for signs of oil.

Timing wont change the actual air fuel ratio, but it may change what the wideband reports. Unburnt oxygen in the exhaust system looks "lean". Usually this is due to mis-fire, but you shouldn't be getting that kind of response due to the reduced timing.This is why I am suggesting you look at the plugs for oil, as it sounds like you are having a misfire, and if the plugs are clean but old, you will want to install new plugs and possibly tune up the ignition system in anyway possible (new wires if you have wires I am not sure if you are DIS or not) just to rule out mis-fires. All it takes is one cylinder to throw a wideband off ( where is your wideband(s) located? )

Once you have verified the condition of the plugs, pcv ,and ignition system, and we see that the plugs are new and clean, the pcv system and pcv valve is good, the ignition system is apparently fine, we can go further. First I must ask exactly what timing you tried, you mentioned 20*. I suggested around 24* and 20 is kind of low, if you had an EGT gauge and noticed the EGT rise while using 20* this would explain why the wideband went lean, your cam is large enough to push the still burning / unburnt oxygen into the exhaust system. (cam specs listed somewhere? this is where tuning gets more personal). For the most part, you will want to add back some timing, but not all of it, figure 24*~ leading up to 25 or 26 by redline. You want the softest timing spot (lowest number) right at, and during the entire peak torque area (this is alot easier with a dyno) and once torque begins to fall off, it is ok to add back the additional degree or two by redline. The bigger the cam the less of this you will need, because a bigger cam tends to carry torque to redline easier (it peaks and does not fall as much, depends on the head/CID).

Without an EGT gauge or dyno, we cannot tune for max performance. But we can try to tune for safety. If the wideband was correctly reporting the exhaust valve event coincided with the still burning mixture at 20*(and not misfire related), it is safe to say that 20* was not enough (EGT would help here). And if the knock was real at 28* region, it is safe to say that 28 is too much. So it seems like 24* (or even 23* in peak torque, with +1 as you exit) is around the correct number, "what it seems to be asking for". If there is still knock with 24* then further testing is required, i.e. you need to go back to 28* and try some 100 octane fuel to verify what we suspect as knock, is not really knock. Sometimes an engine will stop reporting knock due to reduced timing, even though it wasn't really knocking. In other words, just because the "knock" disappears with less timing, doesn't mean it was knocking. Remember these sensors are pretty dumb so we have to be sure in our diagnosis, and we need tools to do this. wideband, EGT, Dynometers, plug reading, compression tests, inspection, high octane test fuel, get as many as you can.

Cliffs;
-verify good ignition system, clean/new plugs, pcv valve
-try 23* -> 24* timing setting (see if the air fuel cleans up and the knock stays gone)
-try 27* of timing again with 100 octane fuel or better to see if knock stays gone
-Since you are using 91, air intake temperature and a rich air fuel ratio is very important. Do what you can to lower IAT with ducting to the best of your ability, and don't be afraid to bring the air fuel ratio down as was suggested, at least for the time being, until you can get to a dyno where you will lean it back out looking for power, while reducing timing and verifying the power stays with reduced timing and EGT does not climb (you dont need an EGT sensor because the torque output will tell you where the fuel is burning, but if you HAD an EGT sensor you would see it stay cool). Street cars do not get timed for max power, because timing changes depending on vehicle weight and road load. So going uphill with a car full of luggage and passengers will cause knock on a timing setting you derived from a dyno tune completed with maximum timing for accelerating a roller (it didn't knock on the dyno, but it will knock on the road).

 

car is 98 z28 the cam is stock, motor is stock, stock ls1 intake with bolt-ons, long tube, lid k&n, the wideband is in the o2 sensor bung on the pass lt header and simulates the narrow band that ok?

How does the pcm know to choose between the high and low octane tables?

I didn't do as good of a job on keeping track of exactly which tune I was on in each log as I normally do but I fixed up 3 different tunes and hit the road logged then changed tunes and logged starting with the most adv working way down but my afr was off and that was distracting me.

ok so another noob question I know when tuning the VE tables I need to be in SD mode. Do I need to be in SD while tuning on the timing? Do I need to have the high and low tables matching like while in SD for VE tuning?

I apologize for all the beginner questions and do appreciate the help

 

The reason I ask about how it chooses from high or low octane table is the timing was never set as low as it got in this log at least in the high table, the low table however is around 19 through that area

 

ok your first graph main spark vs airmass vs rpm open throttle high octane does not appear to be stock values, at 0.60 starting at 4800 the timing get a little aggressive for a stock cam, reduce the timing to 28 from 4800 on, if this does not help, start reducing the timing until you have app 26 for wot, but filter the entire table, dont have spikes in the values..

 

I believe the tune that was on it when I bought it was a hypertech when compared to one,

 

Being that the engine is mostly stock, it will have a sharp peak torque, and lose VE quickly as you approach redline. Timing values should be lowest at peak torque, very conservative (20*~) whether on 87 or 93 octane, you do not want to squeeze a stock piston engine for power with additional timing. The two popular ways to gain power through "tuning" is to lean the engine out, and increase timing advance (typical gimmicks for +20hp). You want NEITHER in a stock application because daily conditions will change and it will become dangerous (its fine on the dyno so you can take a picture and print a graph, but it should be reset back to normal for normal driving). I would change the timing values back to stock or nearly stock for safety, especially in the torque peak regions (through 3500-4500rpm).

I see nothing wrong with simulating the narrowband as long as you have it pretty close (1.004volts = 14.5:1 or 14.7:1 and 0.004volts = 15.1:1 or 14.9:1 should get it "economy friendly" for closed loop) the wideband should have a configurable output you can change to those values if you want.

 

ok and the car isn't a daily driver or anything but its still stock motor bolt ons shooting for 11.999's

 

The wideband simulation is an economy feature to help the vehicle for cruise/idle situation. Will not affect max performance, the ECU does not use wideband feedback (it shouldn't, even if it has the option, you should not depend on it) for wide open throttle situation.


If you are at the track, and running 12.10's and need to squeeze 20 horsepower from a rock, its fine to bump timing a few degrees (use a higher octane fuel if available for safety) and lean out the engine a tiny bit (especially with the better fuel) and hit that 11.99 number. But I would not leave it there.

To make additional power safely, first you determine the max safe limit for the piston/longblock. Many LS owners are squeezing 500~ horsepower or more from their mostly OEM longblocks. I prefer to leave the engine intact (do not open it for 500bhp). Instead of opening an OEM engine with low miles (thus keeping it healthy and clean inside, no mistakes) we prefer to strap on some form of forced induction, if the OEM engine will be reliable with the additional power. This way you can run it around 500bhp for years, then at your discretion convert back to the OEM engine (remove the blower/turbo setup) and sell the vehicle. If the engine has high mileage, and you want to perform a rebuild at some point, then I would examine my head/cam options as budget allows etc... I don't want to turn this into a build thread discussion. My main point was that: squeezing power from a stock engine by using timing/fuel adjustments is a dead end, its ok for the dyno day or that last .1 seconds ET but do not depend on "tuning" for making significant additional power with a stock engine. Instead, tune the engine to be safe for all operating conditions, so it lasts as long as you own it. Additional, reliable power is made from airflow mods, like a turbo. Notice when we add 150 horses with boost what timing and fuel does: even LESS timing, even MORE fuel. The opposite of what you are 'hinting towards' with your naturally aspirated engine now. You don't want to squeeze the timing and fuel for power, you squeeze the airflow, and make it safe to drive by reducing timing and adding more fuel.

If you are looking for "free" power there are many items checklist:
1. reduce vehicle weight, very effective improves everything: handling, braking, acceleration
2. reduce rotating mass, lighter wheels, driveshaft, flywheel, if the car is auto almost anything can be made lighter with good benefits, a manual needs to be careful where weight reduction occurs.
3. tune-up, maintenance, can't say it enough, update the plugs and ignition components, use a high quality air filter, use the right weight oil, synthetic
4. Induction mods, i.e. tubes, air dams, tunnels, cold air inlets, anything to separate the heat of the engine from the inlet intake air pathway
5. to continue #4, heat wrap, blankets, shielding, coatings, any thermal coverings/separations to keep the intake side colder and prevent temp from leaving the exhaust system

I am a fan of anything that can be removed easily, so the vehicle can be converted back to stock easily. Just in case you suddenly decide to buy something else, you don't have a heap of parts invested into a car that becomes a drain (you dont get back what you invest, if you can't easily remove the investments )

 

Here's a pic of the one plug all looked about the same

 

Mainly we are looking for oil, or obvious problems, like chunks missing or melted flakes of piston. The white overall color a nice indicator of economical use of fuel. A good compression test on each cylinder would also be nice to have for record, you should be keeping a log over the years, each year do a test and write it down for each cylinder to the best digit i.e. 145.0psi, 146.3psi, get as accurate as possible. As long as there is no oil and no melted/trouble plugs you can proceed with the wide open throttle runs, data logging, tuning

If you need a more graphical description of my timing discussion from above I can post a picture instead of more words

 

Please do, pic >= 1K words.

 

I'm up to speed with ya but pics are worth a 1000 words ya know