Greenhorn

[Kdukes]

I'm new to EFILIVE and tuning, I am trying to pick up on
what I need to do to fine tune the tune on my vehicle.

I bought a mail order tune and also EFILIVE commercial.
but after my first logging trip I see I have 5 - 8 KR I think it can be better.
and I also want to understand my vehicle better.

Most of what I have read here on this great forum seemed
geared to v8's and I'm not sure what is applicable to my lil ole' IL6

So guys can you tell me where to start . links to tutorials are always appreciated.

[TAQuickness]

Welcome to the forum Kdukes!

I'm sure others will chime in soon to help you out.

[ds8]

You must have a wait4me tune. You need to pull timing out of that tune on the high octane spark table... a lot. Put your original tune back on and start from there. You will lose gas mileage and lose even more power with that particular tune.

Start logging your original tune. You may need to make some filters to prevent displaying knock from when you hit the throttle too hard. Tell about your vehicle, someone may be able to send you the tune from their vehicle.

DS

[Kdukes]

Yes I do have that tune, but I must say that from stock I did actually have gains. I started with about 12mpg city 14.6 hwy and after the tune it went up to 14.1 city 16 - 19 hwy (hwy depends on avg speed of 60 -65 vs 75/80 (leadfoot hysterisis factor).

My wife reports higher mpg's on her 04 EXT also.

I know you say well if its better why mess with it?

1. I bought the software I want to learn how to use it.
2. there was this funky modulation at low rpms on my truck and the shifts were not as firm as i wanted.
3. I find that the modulation isnt there with the stock tune, so I reinstalled the stock pcm and pulled off the stock tune and then copy pasted all the differences. Then I reinstalled the newer pcm (2x actually cuz i didnt realize its the computer thats locked into my cable and not the vin :bash: .

PS: about my vehicle
05 Trailblazer LT
IL6 (stock)
Will be adding a CAI soon.
wishing there was a forced induction kit i can afford.

So with all of that I will now say thank you very much and I will pull some timing in the high octane tables. I hope you understand I came here not to bad mouth or be a trouble maker, only to learn for myself.

[ScarabEpic22]

Welcome aboard man, I bought EFILive first and then bought a PCM4Less tune and compared it to my stock tune, changed some minor parts (removed limiter, etc) and then flashed it to my TB.

Have you started playing with shift settings, Torque Reduction, spark timing, etc yet?

[Kdukes]

Yes I started playing with it, thats how I found out I had what seemed to be a high knock retard. I did some software logging and seat of the pants logging stock / aftermarket tuning.
I was satisfied with the w4me tune, until I started logging. I realize "ALL" mail order tunes have to be rather general just because 2 of the same engines will never be exactly the same, as well as driving conditions and driver.

In the spirit of DIY, which if you don't have a shop and own this program you surely are deeply into Doing it Yourself. I am trying to amass the steps and knowledge to one day be able to help others as well as myself.

[blandmiller]

I don't know about the rest of you, but I am utterly impressed that we now have our own forum dedicated to the LL8.

I would try changing the PE enable parameters and adjusting the fueling before I started pulling very much timing. Some of the spark knock will go away with a slight increase in AFR from stoich. I am running ~12.8:1 and saw ~2-3 degrees less KR.

Erik, what limiter did you remove? I cannot seem to get rid of the speed limiter.

[Kdukes]

I don't know about the rest of you, but I am utterly impressed that we now have our own forum dedicated to the LL8.


Yes I am very excited to see this.



I would try changing the PE enable parameters and adjusting the fueling before I started pulling very much timing. Some of the spark knock will go away with a slight increase in AFR from stoich. I am running ~12.8:1 and saw ~2-3 degrees less KR.


I will attempt to do a little of this tonight



Erik, what limiter did you remove? I cannot seem to get rid of the speed limiter.
I believe what you want is in
{B0920}{B0921}

[ds8]

I had the same problem with that tune...the knock retard was out of control and I wasn't even near entering PE mode. Try tapping your accelerator quickly while coasting along at about 20mph. You will hear the knock. Being that overadvanced is not a safe condition for any engine.

Since we can't change burst knock for this engine, you need to tune it for regular driving conditions without rapid throttle changes. Try to hit as many cells as possible without rapidly changing throttle position. Where the cells are 0, you can increase advance. Where the knock exists, you need to pull some of the advance. Also, log your commanded AFR. If the cells are at 14.6, then change the advance in those cells. If it is near 12.5, you've gone into PE mode, and that can be changed on a different table. I'd worry about PE mode later since the car rarely enters it.

DS

[Kdukes]

DS8, wow, that opened my eyes, thank you I will try some of this once i get home tonight.

[blandmiller]

Who's car 'rarely' enters PE? I thought that was one of the main reasons for changing the factory tune; to get the open loop tables cleaned up to make even power.

I don't see KR unless I am hard on the throttle and not in PE (stock tune). I also would not put much faith in the 'commanded AFR'. There are things going on that do not show up in the commanded value, but show up with a wideband O2.

[ds8]

My car rarely enters PE mode...only gets there when I floor the accelerator. I don't drive like that unless I am on a two lane and need to pass. Commanded AFR tells exactly which mode your are operating in. The computer knows if you are in PE mode or not and figures out if you need 14.6AFR or the value off the AFR in PE mode table{B0901}. Maybe that isn't the actual AFR, but that doesn't matter. What matters is what table is being used under the conditions you have recorded. A wideband won't tell you when you have entered PE mode as precisely as the PCM that puts it into this mode. The commanded AFR tells you what table you should change when changing the timing based on knock retard. The wideband is of little use for timing changes. Fueling changes are a different story. Operating in PE mode means using a lot of fuel. If the computer is using an AFR of 14.6 for the non-PE mode and 12.5 for PE mode, operating in PE mode all the time is consuming almost 17% more fuel for a given RPM and MAP. That's a waste of fuel.

[blandmiller]

I never said to run the car in PE mode all the time. I stated that I do not see KR unless the engine is under heavy load and not in PE.

Your car goes into PE mode alot more often than you think. An ICE cannot run at stoich under heavy loading without generating tremendous amounts of heat that will melt pistons. Engine load and time control the addition of fuel for cooling means.

How does the commanded AFR tell you which table you should change when changing timing to reduce KR? The timing tables are not related to the AFR. The timing tables are based on RPM & engine load.

What are your main objectives by modifying the PCM parameters?

[ds8]

AFR is a function of the mode you are in: PE or non-PE.
PE mode uses the table I referenced in my last message and commands the AFR to whatever is dictated by said table (around 12.5).
Non-PE mode tries to run 14.6

When the commanded AFR is 14.6, PCM is in non-PE mode
When the commanded AFR is near 12.5, PCM is in PE mode

Now you can use the map feature to figure out where you need to pull timing. If you create a map of KR based on rpm and map, create another map of commanded AFR based on rpm and map. This second map will show the AFR for the given cells. An average of 14.6 means that cell was in non-PE; if the average is 12.5 (or whatever the PE AFR is set to), then that cell is for PE mode; if your average is between 14.6 and 12.5, that cell is a mess and a combination of PE and non-PE. Don't adjust timing in that cell. For the cells that average 14.6, adjust the timing in the high octane spark table non-PE mode. For the cells that average 12.5, adjust timing in the high octane table PE mode. Make sure that your low octane tables aren't advanced past the their respective high octane table. The table names are misleading, they are the max an min timing used.

I tune for mileage, but more power is a side effect. This method will reveal how often your vehicle is in PE mode...my vehicle only enters PE mode when I floor it. On my last logged trip, I only entered PE mode when I floored it and the PCM kept it there for 47 of the 50,000 data points I logged. That is less than .1% of the time. If I had not floored the throttle, I would never have entered PE mode.

[blandmiller]

So your method uses the commanded AFR as an indicator as to which timing table (PE or Non-PE/low Rpm or high Rpm) to change?

Have you changed the PE enable parameters at all? My TB will enter PE mode when pulling up a long hill. It also enters PE every time the tranny kicks down.

Are you seeing better mileage by reducing timing advance? If you tune for mileage, I am really surprised that you are not using a wideband and fine tuning the VE tables to get the stoich AFR dead on. I would think that the best mileage gains would come from fuel adjustments first and timing second.

Have you documented any changes in the "engine torque" since you started changing the timing? Are you suspecting that GM negated increases in mileage and power in the programming in favor of lower emmissions?

[ds8]

The commanded AFR tells which table is being used in the mapped cells. This tells which table to change the advance in.

I have changed the PE enable parameters. This is one way to get better mileage. I don't enter it when kicking down a gear nor do I enter PE on long hills.

I'm not sure changing AFR can improve the mileage as much as timing can. I don't have the wideband so I can't be sure of that. I could probably do better with one. Here's my reasoning: the timing is so bad on that canned tune (it's 15 degrees too advance in my cruising zone) that the combustion process is fighting the piston travel. I would have to richen it up incredibly to get rid of that much knock. In that case, the wideband doesn't do me any good because I would be way down from 14.7 :1. Backing down the advance lets the engine run closer to 14.7 because there is no knock. Without knock, the combustion doesn't fight the piston travel resulting in better transfer of energy, and the AFR is lower so less fuel is used anyway. Once the timing is close, then a wideband could be used to tune VE and further change timing.

I've found that the 3 TB's I've checked put out about 112 lb-ft of torque according to the pcm with the stock tune. With my tune I am putting out 116 1b-ft according to the pcm. I haven't checked in a while and have made some changes with 7.3.3, so I don't know where it is now.

GM faces the issue of providing a single tune that works everywhere in the world. That is their handcuff, but I can tell you the stock tune is closer to optimum than the tune originally discussed here. By the way, that tune only put out mid 70's for max torque according to the pcm.

[blandmiller]

Now we are getting somewhere! I'm still not sure how the heavy-load engine heat is being removed without adding fuel, but we can discuss this in detail later. Obviously the PCM will add fuel to protect the engine and catalytic converter somehow.

You have pulled 15 degrees of timing from the cells you cruise in and believe you are getting better gas mileage? What gain in mileage are you seeing? To keep everything in comparison, please state the vehicle specifics; ie 2wd 4wd 3.73 or 3.42 rear axle etc...

You reason that the timing is advanced so far that the peak combustion pressure is achieved before the piston is even at TDC? 15 degrees is a major timing change. Most of the time I am seeing ~23-25 degrees of advance while cruising. Are you actually tuning to ~10 degrees of advance?

You also reason that backing the timing off allows the engine to run closer to 14.7 because there is no knock. I am not sure how AFR is related to or controlled by knock. I have never seen the PCM change fueling based on KR. I do know that the O2 sensors and several parameters make the AFR sweep between slightly rich of stoich to slightly lean of stoich to make the catalytic converter do it's job when in closed-loop mode. Can you expand your thoughts on KR affecting fueling?

How confident are you in the torque numbers and how the PCM is calculating them? Can you relate the numbers you have recorded to any reasonable torque values for our engine? Will you list the operating parameters that were in effect when the torque was 116 Ft# so we can discuss?

I have chassis dyno data and several logged files of my vehicle that we should be able to use to compare and evaluate some of these results.

[ds8]

Now we are getting somewhere! I'm still not sure how the heavy-load engine heat is being removed without adding fuel, but we can discuss this in detail later. Obviously the PCM will add fuel to protect the engine and catalytic converter somehow.

It does add fuel, that is the nature of the VE table. different loads and rpms have different VE's. therefore they will have a different fuel charge and most likely different AFR.

You have pulled 15 degrees of timing from the cells you cruise in and believe you are getting better gas mileage? What gain in mileage are you seeing? To keep everything in comparison, please state the vehicle specifics; ie 2wd 4wd 3.73 or 3.42 rear axle etc...

the canned tune was 2-3mpg worse than stock. I'm probably about 1-3 better than stock. 2wd 4.2 3.73.

You reason that the timing is advanced so far that the peak combustion pressure is achieved before the piston is even at TDC? 15 degrees is a major timing change. Most of the time I am seeing ~23-25 degrees of advance while cruising. Are you actually tuning to ~10 degrees of advance?

between 20 and 35 depending on load for the wait4me tune and 6 and 28 for my tune

You also reason that backing the timing off allows the engine to run closer to 14.7 because there is no knock. I am not sure how AFR is related to or controlled by knock.

knock can be eliminated by running rich...you see this on your own car when you said you have no knock in PE.

I have never seen the PCM change fueling based on KR. I do know that the O2 sensors and several parameters make the AFR sweep between slightly rich of stoich to slightly lean of stoich to make the catalytic converter do it's job when in closed-loop mode. Can you expand your thoughts on KR affecting fueling?

You would have to run extremely rich to eliminate the knock from 16 degrees too far advanced. It's easier and engine efficiency is better if you pull the 16 degrees than to run at 10:1 AFR.

How confident are you in the torque numbers and how the PCM is calculating them?

They are not close at all to what the engine really makes. They are used to make assements on what to do with the transmission. off topic - There is hardly any torque reduction when you use this number in the tables.

Can you relate the numbers you have recorded to any reasonable torque values for our engine?

assume 112 is proportional to 275 ft-lbs. then 116 gives you about 284lb-ft.

Will you list the operating parameters that were in effect when the torque was 116 Ft# so we can discuss?

too many to list

I have chassis dyno data and several logged files of my vehicle that we should be able to use to compare and evaluate some of these results

[Kdukes]

F@&^%, You 2 are Wayyyy over my head.
And I thank you! Now I have an idea of what things
I need to learn.

How bout a lil handholding for us newbies?

I know I need a baseline before I can make any
comparisons or adjustments.

Please give me some direction on what is Really important to log and how.

For instance:
Use this set of PID's {........}
Drive 10 miles city followed by 15miles Hwy and do 3 WOT from dig and 2 from ~45 - WOT and 2 from ~65 - WOT

Then take note of the {...} and {...} .
What you are looking for is fluctuations here and there.....blah blah

I think if that kind of knowledge were passed along I would grasp it much easier than

"Look at your VE table and keep X within 20% of Y @ 17* btdc"

Would that be doable?

[ds8]

These are the ones I am using:

OK DESCRIPTION CAPTION UNITS SYSTEM CH PARAMETER
Y Calculated Injector Flow Rate (Generic scan mode only) INJFLOW Grams/s,Lbs/Min Fuel 2 GM.INJFLOW
Y Calculated Load Value LOAD_PCT % Performance 1 SAE.LOAD_PCT
Y Cam Phase Angle Desired CAMPA_DES Degrees Conditions 2 GM.CAMPA_DES
Y Commanded Air Fuel Ratio B AFR_B :1 Fuel 1 GM.AFR_B
Y Damped VSS DAMPVSS KMH,MPH Performance 0 CALC.DAMPVSS
Y Delivered Engine Torque to Transmission TRQENG_B Nm,Ft-Lbs Transmission 2 GM.TRQENG_B
Y Engine Coolant Temperature ECT °C,°F Temperature 1 SAE.ECT
Y Engine RPM RPM RPM Conditions 2 SAE.RPM
Y Ignition Timing Advance for #1 Cylinder SPARKADV Degrees Spark 1 SAE.SPARKADV
Y Injector Pulse Width Injector 1 INJ1PW ms Fuel 2 GM.INJ1PW
Y Intake Air Temperature IAT °C,°F Temperature 1 SAE.IAT
Y Intake Manifold Absolute Pressure MAP kPa,inHg Air 1 SAE.MAP
Y Last Shift Time SHIFTLAST Seconds Transmission 1 GM.SHIFTLAST
Y Long Term Fuel Trim - Bank 1 LONGFT1 % Fuel 1 SAE.LONGFT1
Y Retard Due to Knock KR Degrees Spark 1 GM.KR
Y Short Term Fuel Trim - Bank 1 SHRTFT1 % Fuel 1 SAE.SHRTFT1
Y Throttle Position TP % Throttle 1 GM.TP
Y Transmission Fluid Temperature TFT °C,°F Temperature 1 GM.TFT
Y Vehicle Speed Sensor VSS KMH,MPH Conditions 1 SAE.VSS

[Kdukes]

These are the ones I am using:


Cool, I get out of here in bout 30 mins, I'll change my laptop and do a log on the way home . Would you mind looking at that later and telling me what you see?

[ds8]

I can do that for you. That'll be fun, thanks. If you can, do one longer log of normal driving and then do one short one where you drop the hammer and get max rpms out and hit 60-70 mph. don't beat on it for me though...only if you want to.

[Kdukes]

Not that I've seen it exactly spelled out but when logging should you be
trying to get as many different acceleration and deceleration scenarios as you can or just drive like grandpa to the bingo hall?

[ds8]

Try to fill all the cells up on your knock map. Constants speeds can do that if you drive through hills. You can drive around changing the throttle to get all the cells, but you can induce burst knock into the knock table and can't remove that nor would you know that happened unless you watch. You have a couple other choices. Cruise control though hill terrain gives you constant speeds with varying load. Or, constant load as speed increases will fill up the tables horizontally. I find it easiest to hit the cruise and get the cells to fill up that way. When you have all of one column filled, adjust the speed some and get another column to start filling. I live where I can drive though plenty of hills and find on-ramps so it may not be as easy for you.

[blandmiller]

The VE table is actually indicating the engine's ability to completely fill the combustion chamber with air. It's nature is not to add fuel, it doesn't care about fuel. The VE tables are used to calculate the air/fuel charge.

6 degrees of advance sounds way out there, but I guess it works for you.

I am still confused as to the timing controlling AFR in closed-loop. The PCM already backs timing when it encounters knock while it is still toggling around stoich. KR has no effect on the commanded or actual AFR.

I agree that pulling timing is easier than adding fuel to reduce KR, but 16 degrees seems extreme. Are you seeing 16 degrees of KR? Allow me to quote ds8 from 10-11-06 on another forum, "My knock retard was at 8* at RPMs greater than 1400 all the way to redline with MAP at or above 85 kpa. KR was at least 5* in the same RPM range with MAP at or aove 50 kpa."

How about posting a screenshot of your 'low Rpm non-PE spark advance' table.

I am not trying to be a pain, I just want to try and understand what you are doing.

[ds8]

I never said that commanded AFR changes knock, that is your supposition. AFR of 14.6 tells you that you are not in PE mode and that you should be taking out advance in the non-pe table.

The VE table is actually indicating the engine's ability to completely fill the combustion chamber with air. It's nature is not to add fuel, it doesn't care about fuel. The VE tables are used to calculate the air/fuel charge.

VE is really an arbitrary number since the I6 (pre-maf) doesn't know directly what mass/volume of air is really entering the intake. The air fuel charge is commanded to 14.6, but by chaing VE you can produce different true AFR's because the injectors pwm is determine by looking at a VE table based on load and RPM. Put in a higher VE value and the engine will run rich (on the wideband) even though the commanded AFR is still 14.6.

I agree that pulling timing is easier than adding fuel to reduce KR, but 16 degrees seems extreme. Are you seeing 16 degrees of KR? Allow me to quote ds8 from 10-11-06 on another forum, "My knock retard was at 8* at RPMs greater than 1400 all the way to redline with MAP at or above 85 kpa. KR was at least 5* in the same RPM range with MAP at or aove 50 kpa."

I think the max retard the pcm can command is 8 degrees. I have never seen more than that even though the timing was advanced 16 too far.
I pulled 16 degrees out of the wait4me tune. The most I pulled out of the stock tune was 9 degrees and many of the fields were only 2 to 3, and I added a bit in a few cells. This is why the stock tune is far superior to the wait4me tune.

[blandmiller]

From today at around noon "Backing down the advance lets the engine run closer to 14.7 because there is no knock." What did you mean by this statement?

VE is absolutely not an arbitrary number. A MAF sensor tells the PCM the amount of air passing through it (to the best of it's ability). The VE table is used to provide the same information, but it is not actually measuring the air. These tables are predicted airflow values from the factory and may not be as accurate as you think. I believe you are incorrect in assuming that changing the VE table will make the engine run rich when you are commanding 14.6. Normally, if you are commanding 14.6, you are (by your previous admission) in closed-loop (non-PE) and fueling is controlled by O2 sensor readings, LTFT, and STFT (and those pesky pv=nRT calculations).

I have not seen any indication that the maximum KR range is 8 degrees. If this is true, it is good info. I do not believe I have ever seen more than 8 degrees of KR, but never assumed it was a max value. I will keep it in mind and see if it holds true in my tune.

Just a thought, can you post a log file containing the KR of 8* from 1400 to redline? I have never seen anything like that.

[ds8]

From today at around noon "Backing down the advance lets the engine run closer to 14.7 because there is no knock." What did you mean by this statement?

All that I am saying is that ICE's can be run rich to reduce knock or the advance can be reduced so the car can run leaner.


VE is absolutely not an arbitrary number. A MAF sensor tells the PCM the amount of air passing through it (to the best of it's ability). The VE table is used to provide the same information, but it is not actually measuring the air. These tables are predicted airflow values from the factory and may not be as accurate as you think. I believe you are incorrect in assuming that changing the VE table will make the engine run rich when you are commanding 14.6. Normally, if you are commanding 14.6, you are (by your previous admission) in closed-loop (non-PE) and fueling is controlled by O2 sensor readings, LTFT, and STFT (and those pesky pv=nRT calculations).

They are not accurate, that is why I wrote that it is an arbitrary number. All the things you wrote change the fueling too. So how can VE not be arbitrary. how can a naturally aspirated engine have a volumetric efficiency higher than 100%, but our tables have it. VE is just a guide of where to start the AFR. If we didn't have all th other controls (LTFT,STFT, etc) increasing VE would add extra fuel and reduce the afr. I think you can still change the aft by changing VE, but it's not going to go from 14.7 to 12. Maybe 14.7 to 14.5. It would be best if we could just get to this value on a table like we can do with PE afr.

[Ira]

A naturally aspirated engine can have a VE over 100% and it's possible but not likely that a modern production might actually do that over a very narrow RPM band. The VE table tell the ECM how much air is entering each cylinder given the current operating conditions of the engine. That information and the fuell pressure and injector tables allow the ECM to calculate the injector open time for the AFR it's currently trying for.

A MAF allows an engine with a messed up VE table to still run decent as the ECM will normally prefer the MAF numbers over the VE numbers. A SD engine is much more dependent upon the accuracy of the VE table as it only has that one way to figure out the amount of air entering the engine.

One the VE table on a SD engine is correct you should be able to use PE and other fuel tables to define the AFR you're looking for and the ECm should be able to figure out how to do it.

Using the VE table to set AFR will work, but long term you're tune won't make a lot of sense because you'll be asking for one AFR and getting another.

Ira

[ScarabEpic22]

Wow guys, guess I have some reading to do later this week when I have an hour or so to digest this thread... My PCM4Less tune has very little knock retard IIRC (its been a while since Ive logged KR), but I will check it soon and try and get back.

[blandmiller]

There is a very good explanation of the various forms of "VE" (used very loosely) on redhardsupra's blog site. Don't think of the VE as only volumetric efficiency. It has several other forms and units. I still haven't made complete sense of the tables we currently have, but I will continue to work on it.

I still say the VE tables are not arbitrary or the open-loop fueling would be way off (if you use the % maximum value). I can change the PE AFR and see it reflected in the wideband reading. There are several places where the commanded and actual are not as close as I would like them.

[ds8]

I checked a log file. My calculated load ranges from 0 to 100%, my throttle position ranges from 4.7 to 100%. Here's the interesting thing: any throttle position over 31.5% shows 100% load. Throttle opening influences VE, but according to the table in EFILive referenced by the PCM, I can't increase VE for any throttle position above 31.5%. This can't be true because the throttle has much more opening to do and VE could go much higher. If I'm roughly open a third of the way, there is at least twice as much area left to open. My VE would likely double and be well over 200%...Those numbers are just for reference because there are many different gains in the system that we can't see.

[blandmiller]

I would agree that throttle opening (ie MAP) influences VE. I am not completely sure that the column headers (or the calculated load% PID) are correct in our VE tables. What are the values of MAP and BARO when the %load first hits 100? Are you logging APP, TP, or ETC?

Why would you think your VE would double by opening the throttle plate ~66% more? The mass flow will increase if you are not already at BARO pressure behind the throttle body, but the efficiency would not double. The efficiency is the ability to completely fill the chamber with "actual" air mass (taking pressure and temperature into account).

Can you post one of your log files that show the 8 degrees of KR from 1400 to redline?

[ds8]

If the throttle area increases linearly (it really doesn't), the increase is not 66% when going from 31.5% to 100%, it's 217%. My PID's are listed in a previous post. Our barometric presure is around 101 kpa here and the MAP sensor reads around 70kpa when I hit 100% load. I've attached a really old log file. I won't run that tune anymore so I won't gather new data with my current PID's.

[blandmiller]

Wow, that file has alot of PIDs slowing it down. 33 PIDs using 37 channels and updating at ~1 fps? I assume this was one of the first logs. I saw a little burst knock, but not anything like what you had described. This log file doesn't even go above 2700 Rpm or 57% TP.

The calculated load percentage value uses current airflow/peak airflow and corrects to STP. I have no idea where the airflow numbers are coming from. None of them make any sense. I would think that the %load would be based on MAP/BARO.

[ds8]

I have very few logs saved from running that tune. I've deleted most anyway since the tune was so bad and I only used it for about a week. I now run the PID's listed earlier which run at a significantly higher rate.

[traumadog]

Hey - another newbie here.

Just out of curiosity... the LL8 profiles list two octane tables. What would make the I6 program switch from one to the other? We don't have less than 87 here, and we top out at 93. So would there be any benefit to switching by default to the high-octane table?

[Whodunnit]

Greetings. Wow! Let the greenhorns unite!

I too am new to this and am trying to get a feel for what is "normal and acceptible" before I start digging into tweaks. I am seeing quite a bit of knock-related activity with my stock tune on 87octane gas and would like to know if it's reasonable or potentially a problem exists.

Here's a screen cap from some recent driving.
http://i157.photobucket.com/albums/t53/bretwylie/trailblazerstuff/KRTrends.jpg

What do you think?

[Whodunnit]

*bump*
Come-on, I know someone has glanced at this KR trend and thought either:
a) looks normal to me...
b) wow that's some knock! there's something wrong going on (bad gas etc...)
c) looks like maybe the data trend is wrong... (did something such as conflicting channels being trended mess up the scaling?)

If you don't mind sharing your input, I'd love your help! Thanks!

[joecar]

Bret/Whodunnit,

That's too much knock too often...

Try these things:
- 91 octane gas (you live in CA);
- clean the MAF sensor (use only CRC "MAF Cleaner" or CRC "QD Electronic Cleaner"... do not use "Electrical" cleaner or "Brake" clean);
- check to see if oil is being pulled into intake via PCV valve;
- are your spark plugs in good condition;
- is engine coolant temp. overheating (is ECT sensor reading right);

Joe

[ScarabEpic22]

No MAF on the P10 LL8s, SD only. No PCV valve, exhaust VVT takes care of that (ok there is one but no one has reported any problems with them even after a few hundred K).

[Whodunnit]

Thank you very much guys!

Okay, after about 60k miles, it's probably well past time to change the plugs. I haven't pulled them yet, so I don't know the condition, just yet. (What do you think, wires too? Any recommendations on plugs or wires for Trailblazers? I use Magnacore wires on my Merkur...)

I've also been experimenting with better gas and think there's been some improvement there as well.

If that doesn't solve it I can dig down into the PCV option.

As far as ECT, it 'seems' to be okay and has always indicated as I would expect. The engine runs mid range, and I'm thinking the likelihood of having a faulty thermostat and a perfectly wrongly calibrated ECT sensor is probably very slim.

It seems like it's detecting knock when the engine up-shifts and here as I drove on flat freeway and then up a bit of a grade. Most trends aren't quite this bad, but, I don't think it would be a good idea to start tweaking until I get to a good and safe starting point.

Thanks again, I really appreciate your help!

- bret

[ScarabEpic22]

No wires on the LL8, coil on plug. Plugs are good for 100K, I made the mistake replacing them at 50k with Bosch Platinum +4s for ~25K and then yanked em for the stock iridium AC Delcos. Dont waste the $$ on plugs, just pull them out, check them, then use anti-seize otherwise it can be a pain later down the road to pull them.

Thats where Im seeing KR, Im running 0TM and hear a ping every once in a while when upshifting, but more often in 4th on the freeway at ~65-75, it will ping then kick the TCC off lockup.

[Whodunnit]

Alright, thank you! I guess I should look under my own hood a little more often. :doh: I'll go ahead and do just as you say and post back to ya.

Yup, that's where I'm seeing KR most too. Thanks!

[bpayne_69]

Bret/Whodunnit,

That's too much knock too often...

Try these things:
- 91 octane gas (you live in CA);
- clean the MAF sensor (use only CRC "MAF Cleaner" or CRC "QD Electronic Cleaner"... do not use "Electrical" cleaner or "Brake" clean);
- check to see if oil is being pulled into intake via PCV valve;
- are your spark plugs in good condition;
- is engine coolant temp. overheating (is ECT sensor reading right);

Joe

Joecar, I noticed that the inside of my intake (behind throttle body) has a good bit of oil on it. It looks pretty wet and seems to be comeing from the vacuum hose that comes into the intake just below the brake booster vacuum hose. I don't think it's the PCV hose, but it does look like it is comeing out of the block. What causes this or what else should I check? Thanks.

[joecar]

Oil and oil vapour reduce the "octane number" and may induce/allow ping...

On F-body cars, the PCV hoses come off the rear of both valve covers, merge into one tube that runs to the front, thru PCV valve and into the intake manifold (just downstream of the throttle blade)... when accelerating, oil is pumped up the pushrods and floods the valve cover area, and the g-force pushes the oil rearward and into the said hoses and gets sucked right into the manifold... brilliant design, gets all your oil changed every 3K miles by virtue of you having to add 1 qt every 500 miles... :bash:


I am not familiar with your car, are you sure that the hose you mention is not feeding the MAP sensor...?

If it is coming from the block, then it may well have to do with crankcase ventilation, and you could be getting oil thru it;
if can you splice in a clear tube you will be able to see if that's where oil is coming from.

There are also other means that oil can enter the intake manifold.

[ExtTB]

i was getting a bank to rich error and adjusted the injector flow rate up and it went away...if i adjust it down it comes on more often...i thought it would be the opposite...i was thinking since my I-6 has 156,000 maybe the ejectors are worn

[Whodunnit]

Hi folks!

As suggested, I've been running with 91octane for a while now, but I'm still not quite seeing the MPG I was hoping for and it seems like the idle is a little rough at times; sometimes stumbling when I first give it gas. Though I've never "heard" a knock with this car, I was seeing KR's of around 5-8 before (89octane) and now its more like 2.5. Is this consistent with what you would expect from normal commute driving or should I keep searching until I get down to 0 KR?

(attempting to attach a couple .log files for your reference)

Also perhaps worth noting is that I had found some oily residue present around the airfilter box and intake ducting (post-filter), but I used to think that K&N would make sure their filter oil couldn't cause other problems with the car. Perhaps I was wrong and should try to prevent any loose oil in there as well...I'll work on that side of things, but if anyone wouldn't mind taking the time to offer additional advice, I'd really appreciate your help! :master:

Thanks for your advice!

- bret

[ScarabEpic22]

Can you post up your current tune so I can check it out? or email it to the email addy I have in my profile. If you want me to help you with the trans or some minor engine tweaking let me know. :D

[Whodunnit]

My current tune should be bone stock. '03:frown:

I do have slightly larger tires (+2.4") and a K&N air filter. Other than that... hmm....

Thank you so much for being willing to take a look!!! I really appreciate any help I can get.

- bret:cheers: