Doing WOT Tuning Tests Runs....

[majorpayne317641]

I have a 97 Corvette A4. 5 angle valve job polished intake/exhaust ports, cold air intake, 3.15 final drive gear, 1.8 roller rockers, beehive springs, throttle body bypass, 160 thermostat, tranny cooler, TCI 850hp 4l60e (they said if I break it they give me a new one within 3 years mileage unlimited so w/e! ), TCI 1800 stall, tune by me.

With that being said.

I have noticed that my knock sensors are acting up at WOT regardless of what RPM I start at, and happen randomly, sometimes a WOT run will yield no knock at all (all on the same test run). It happens mostly on a 2nd gear WOT starting at 2000 rpm taking 8 degrees of KR. Thats a lot of potential power lost.... Also happens randomly in the 6300 rpm range right before a shift from 1st to 2nd...

I'd like to know if anyone has encountered this issue with the LS1 and what any recommendations might be. I am thinking of desensitizing the Global Knock sensor table in the 95 to 105 map range but the values do not have any units to them, if anyone knows what value will work best, that would be great.

My other thought is to change the tip in sensitivity as well but again, I don't know the units and by how much to increase them.

Yes I have a WB, yes I log it, but its logged on LogWorks because yes I have hpt standard. Regardless, I have matched up the graphs and my AFR is averaging 12.8 at all the WOT tests.

Please PM for tune and scans since I have had no responses thus far. Thanks.

[LSxpwrdZ]

How much timing are you running and what octane?

[TXZ0603]

post tune and log

[majorpayne317641]

How much timing are you running and what octane?

93 octane always, and total spark advance at point of knock is in the 22's during a 2nd gear run starting at 2000rpm when it should be about 28 or 29 depending on cell.

[majorpayne317641]

here it is

[majorpayne317641]

So do we have any suggestions yet? I have searched everywhere on this forum and the internet and have no real answer. Maybe someone with some experience can recommend how to set the knock sensors or whether to limit any other parameter...

[Frost]

Your timing is high all over. The knock 'looks' real in the log. It's where I'd expect to see it in the places it shows up. Your VE is very rough.

[majorpayne317641]

Your timing is high all over. The knock 'looks' real in the log. It's where I'd expect to see it in the places it shows up. Your VE is very rough.

I was listening for the knock while I was driving, its supposed to sound like marbles but I could not hear a thing. Ik my VE is rough, I logged many hours to get my ltft right on the VE table, should I try smoothing it? I am just afraid its going to skew the ltft's again.

As for the spark, I have it set pretty high, however, I spoke with a friend who is a mechanic, he says our LS1's can generally run 40 degrees total timing at WOT in certain rpm's and that if I can't hear it, it is not knock. What are your thoughts?

Thanks for the input so far though!

[LSxpwrdZ]

Better not run no 40* at WOT on anything.. even LT1's don't take timing like that.

Your timing isn't too far off like it is, but is a little rough like the VE table. I did alot of ignition timing tuning at the track on a LS1 and the car loved around 27-28* timing.

Now your knock... I don't see an AFR being logged but just judging by the narrowbands we know it's not going leaner than 14.7. Also the knock takes place as soon as you open the throttle quickly. First thing that came to my mind was Burst Knock. Your Burst Knock table is set at 0 which means any amount of increase in cylinder airflow will enduce burst knock predictions. Set that value to "0.25" and then go do a log again and see what happens.

Basically by setting that table to 0.25 you are telling the PCM that burst knock can't take place unless the g/cyl increase by this amount rapidly.

[majorpayne317641]

Ok I will try that, now as for the burst knock, you just said to set it to .25, is this a ratio? I understand they have some values leading up to 16 if this is the table I am thinking of, what would be .25 what would be 4 etc? Is this in dB or is it a modifier of a set dB?

Read it again lol yeah I get what the .25 is, but what about those tables that have values up to 16 in the knock sensor sensitivity like global gain, what are those units?

I also had some knock (I didn't actually hear it myself) at about 6300, I had to let off a few times I couldnt hold the car down in first and when it shifted to second at about 50 - 60 my tires lit up again lol so I am not sure if this knock is high rpm real knock or just an inconsistent throttle due to my driving? I have looked at my logs and there is no one exact predicable knock area every time I do a run, thats what confusing to me, that means if its real knock, its inconsistent, or if its not, its some other noise. What do you guys think?

Thanks

[LSxpwrdZ]

after taking another look I don't think it is Delta Air/Burst Knock because you have the ECT table 0'd out for that. The recovery rate is stock, and the sensor sensitivity is stock. Looks like it is in fact picking up knock or something is happening. I would de-sensitize the knock sensors and also get your fueling lined out cause your LTFT are adding 10% fuel at WOT.

Globally pull 2-3* timing from the main spark tables and get your VE and MAF tuned to within 2% error of commanded AFR. The LTFT right now are adding in 10% fuel in places and your commanding an 11.16:1 afr but only running 12.8 afr. It is very possible your VE/MAF tune is really lean causeing fuel trims to be off and WOT fuel to be off. All these conditions make for an unstable tune and will cause inconsistant knock

Also clarify exactly which table you are talking about... what is the title at the top of the table when you open the table up?

[majorpayne317641]

knock sensor global gain vs. map. vs. cyl
knock sensor level tip in tps
knock sensor level vs rpm vs cyl

And by how much should I desensitize the knock sensors, which table is best for this I'm thinking one of the above? This leads back to the question of the global gain numbers and what the units are for them...

Here is a revised tune file for ve, maf, and spark advance smoothing, better looking, I'm gonna see how it runs in the car, if no better luck, I will re-tune the maf and ve for the higher values.

(I will attach in second post. not working right now)

[majorpayne317641]

Here is the revised file I'll try to run, if no luck then I will go back to re-tuning ve and maf in those specific areas.

[LSxpwrdZ]

knock sensor global gain vs. map. vs. cyl
knock sensor level tip in tps
knock sensor level vs rpm vs cyl

And by how much should I desensitize the knock sensors, which table is best for this I'm thinking one of the above? This leads back to the question of the global gain numbers and what the units are for them...

Here is a revised tune file for ve, maf, and spark advance smoothing, better looking, I'm gonna see how it runs in the car, if no better luck, I will re-tune the maf and ve for the higher values.

(I will attach in second post. not working right now)

Okay the Global Gain vs. MAP vs. CYL is a multiplier
Knock Sensor Level is the level from the knock sensor required to determine the engine knocking under it's conditions.

I use the Knock Sensor Level to desensitize myself but the global gain can be used as well by lowering the multiplier.

[LSxpwrdZ]

I had to upload to LS1Tech and then link it to here thats why the filename is crazy lol. That was created with the Beta version so if it doesn't open that is why.

[majorpayne317641]

Ok, understood. And yes I don't have beta, I'll email support to get it, I have saved your file and I'll take a look as soon as possible with software upgrading. Thanks so much for your help, hopefully I'm not too far set back from this, I thought my ve and maf and spark should be smooth like factory tables, its only natural that an engine works exponentially or linearly not just jumping around, I was trying to learn, now that I understand how to tune those areas, I think I need to look at how to adjust numbers on those tables to smooth things out and not mess up the ltft's and afr's. Any advice on this area or does it just turn into experience, science, common sense and art?

[LSxpwrdZ]

The file I uploaded there has the LTFT's turned off. Your o2's are still working with STFT though. Basically you need to tune each mode. I start off with the VE tuning first which requires you to turn the MAF sensor off by failing it out. Once you do this the only fuel adjustments you need to make will be to the Primary VE and then copy those changes to the Secondary VE. The Power Enrich Fuel table I changed to reflect a commanded afr of 13.0-12.7. You need to log the commanded afr and compare it with the actual afr and then compensate your VE accordingly.

Once you get the VE tuned out then you'll move on to the MAF tuning... you'll need to disable dynamic airflow calculations (disable VE) and run purely off the MAF table.

This is much much easier to do if you have a way to log the afr into the VCM Scanner.

[majorpayne317641]

Yes very true, and I have basically done these methods, but I tuned with the NB for anything under WOT and then with the WB for WOT. I am thinking of placing pins into the EGR at the PCM and run the WB through that with the write up I saw on the corvette forum link on this site, it would work well. Until I buy the pro, this way will have to do for my car....

Since I have all of the separate tuning files still saved I can quickly go through the steps though because its already set, I just need to load the programs onto the car. I think I can adjust those problem cells without loosing my other areas that are ok simply by going back to the ve and maf tuning files I have.

I am going to log and also watch the wb while im doing this to see that the NB's are giving me correct info....

Then I'll go back into the PE and just accordingly and see if it works out.

[LSxpwrdZ]

You dont want to adjust the PE for your WOT fueling. PE is a commanded afr. You use that table to tell the PCM what afr you want to run while in PE. You take the stoich afr and divide it by the PE table value.

Example if you want to run 13.0 afr when running WOT you would enter a value of 1.13 because 14.68/1.13 = 12.99. So the PE is a constant not something you just adjust up/down to get the desired afr. For WOT fueling adjustments you need to make those adjustments in the VE table or on the MAF table

[Frost]

...
As for the spark, I have it set pretty high, however, I spoke with a friend who is a mechanic, he says our LS1's can generally run 40 degrees total timing at WOT in certain rpm's and that if I can't hear it, it is not knock. What are your thoughts? ....

I think your mechanic friend doesn't know the difference between your engine and a small block chevy.

I see what else is posted, dulling the knock sensors is what you do AFTER you are sure your knock is false; I am almost sure that most is real.

I see some mention of burst knock needed, but if you look at the file where knock precedes the WOT step, you are cruising at 40.5 deg and its still high when you mash the pedal. Your mid 3K knock is happening at 28.5-29.5degrees... which really IS too high.

IF you have a wideband, using NBs to tune doesn't make much sense. You can get it done with a wideband in a fraction of the time and the weird jagged edges in the MAF and VE will not be present (assuming you only copy good data).