Tuning for dummies, where to start

[louvered97gtp]

After reading help, and other posts, all this jumping back and forth has left me more confused than enlightened. I've not found any stickies or demos that help one get started either. I'm sure the info is there, I may just need a little push to get started. I'm looking to reduce KR.
Is there some logical sequence to begin tunning? I.e.. zero out certain tables, adjust MAF, then fueling? Or back and forth?

From there, is there an explanation of how to safely start changing values? Do we multiply the existing values by 10% and increase or decrease all these values across the board until we get better performance and reduced knock? I doubt it's just random #'s changed in alternating cells.
If you can point me in the right direction to some links, I'd greatly appreciate this. It's been hard going from post to post trying to make sense of all this.
Thank you.

Steve

[Eddie-98GTP]

Hey Steve.

The following assumes a good free flowing exhaust (u bend deleted and non restriced cat (3" downpipe w/ highflow cat is a good first mod)) and CAI of some kind...

First thing you need to do is work on fueling. If your fuel trims (LTFT) are consistaintly between -5 and 0 and your LTFT is always 0 when in PE (ie. AFR below 12 when WOT), then you need to see where you are getting the KR.

The first thing to do (IMHO) is to verify you're not running too lean. With a wide band O2, you want to see around 11.5 AFR or so (depends on mods). If you are using your narrowband O2, then look for O2's in the 930-940 range (again, this depends on mods).

If you're fuel is OK, then look to see how much advance you're commanding. On a SC car, shoot for 17-19*. If you can not run 15* at WOT with AFRs in the 11.3 range (950 O2s), then you may need to reduce timing or add mods to support your current config.

Also, take a look at the AFR Spark table. this table will add a lot of advance if your commanded AFR drops below 10.7. Even at 11.7, most will add 3* or so.

What has been done to the car? It seems many here don't add this info to their sig, but it sure helps in giving advise. If you're running an innercooler, headers, and cam, this advise may be off a little. If you're running a 2.8" pulley with a completely stock everything else (I'm sure you're not, this was sarcasm), you need more mods

[BlackGS]

Is the KR you are trying to remove at WOT? Some people have part-throttle KR also, so post a scan and give us some details.

I started tuning by getting part-throttle response in line. In order to do that, you should drive at least 20-30 minutes and log the LTFT's. When you get a nice large count, look at the averages and see where the LTFT's fall in different rpm ranges and different MAF ranges. You want them as close to zero as possible. If they are averaging positive, multiply your MAF table by a number greater than 1. For example, if you have LTFT averages around +5, try multiplying the MAF table by 1.05 (105%). If the LTFT's are averaging below zero by more than 5, multiply the MAF table by a number less than 1 (.95 for example). After changing the MAF table, drive around again for 20-30 minutes and repeat the process until the LTFT's are close to zero on the negative side. Once you have LTFT averages across the table close to zero, you can get them closer for each MAF cell by multiplying individual MAF cells the same way.

Once I had part-throttle fueling good, I increased timing in the part-throttle rpm ranges, and removed timing adjustments from any other table that might change the numbers unexpectedly. There are three tables under Spark Control that should be considered: IAT, ECT, and AFR. You have to either zero these tables out, or understand what impact they will have on timing, and use that knowledge when entering timing values in the main table (High Octane).

When part-throttle is tuned right, WOT will be that much easier to work with. To get rid of KR at WOT, you want to keep an eye on two main numbers in the scans: AFR and timing. You also want to note what MAF frequency ranges you hit during WOT. You really want to be working with a wideband O2 sensor to get accurate AFR readings, but you can use the narrowband stock sensor to at least see if you are making changes. First, get a few good scans at WOT. Note the timing, especially right before the KR starts. Look at the O2 values at this point. As mentioned, they should be 930mv or more. If they are not, you need to add more fuel and see if that helps. Check your injectors first - if they are not maxing out, then you can add some fuel by increasing the MAF table. Multiply the MAF in the WOT cell ranges only, not the whole table, otherwise you'll mess up the part-throttle tuning you did already. Since you want more fuel, you multiply the MAF cells by a number greater than 1. I usually start with 5% (1.05) and fine-tune from there.

If adding more fuel doesn't help the KR, you will either have to reduce timing, or get more mods! At one point, I had my timing in the upper boost/rpm cells as low as 10 degrees. Not the best for trap speeds, but it kept KR away, and I still had plenty of power down low. Ideally though, you want to try to have zero KR with upwards of 18 degrees of timing most of the time. Not all cars will be able to do this though, so don't just adjust your timing table to 18 degrees in the 5200/.92 cell and think you can go test!

Finally, if these suggestions don't work, just post your scans here and someone will be smart enough to figure it out!

[louvered97gtp]

Thank you for your response guys. I've added my mods to signature. i'm dealing with my 97GTP (daily driver)at moment. I can't drive the car out of my block due to severe KR at low idle. I rebuild my own engines, and the bottom end on my 97 is stock for now since I have bought the best goodies for my 99GTP (track car). therefore, i'm reallly worried about blowing chunks off my stock pistons. I am still reading your posts, and trying to understand a bit better. I am looking at what you've said and reviewing my scans. In the meantime, here is a scan while driving down the street a few houses and back. Lastly, how do I reduce timing? do I remove 10% from all the numbers in the spark advance >High octane or Low octane area?
Your suggestions are very very appreciated

[Eddie-98GTP]

Well, I can't look at the scan since I don't have an HPTuner, but if you're seeing KR at low engine speeds/low loads (you had said something about KR at idle), you either have

1. Something hitting the exhaust, the sway bar has been a problem for a lot of people.

2. Bad knock sensor(s)

3. A shit load of carbon in the engine

4. A mechanical problem.

It's VERY hard (if even possible) to get detonation at idle unless there is something else really wrong. How does the engine sound? Any rattling sounds like somthing hitting (like sway bar as mentioned above)?

My guess - it's false KR, but don't just take my word for it. I've been a professional ASE auto tech for over 18 years, and have seen many things I didn't think were possible (like fuel in a PCM!). Be sure to check everything that could fake the PCM in to thinking the engine is detonating.

[louvered97gtp]

Well, I can't look at the scan since I don't have an HPTuner, but if you're seeing KR at low engine speeds/low loads (you had said something about KR at idle), you either have

1. Something hitting the exhaust, the sway bar has been a problem for a lot of people.

2. Bad knock sensor(s)

3. A shit load of carbon in the engine

4. A mechanical problem.

It's VERY hard (if even possible) to get detonation at idle unless there is something else really wrong. How does the engine sound? Any rattling sounds like somthing hitting (like sway bar as mentioned above)?

My guess - it's false KR, but don't just take my word for it. I've been a professional ASE auto tech for over 18 years, and have seen many things I didn't think were possible (like fuel in a PCM!). Be sure to check everything that could fake the PCM in to thinking the engine is detonating.

I think you might have hit the nail on the head. there is a faint but peculiar noise I can hear. I just noticed today that the car is shaking a bit more than usual while idling. What is the procedure for testing the knock sensors? I suspect it is false knock, I may have to pull the engine and inspect the bottom end again.
Thanks a bunch guys.

[JerryH]

- Loose rocker bolts?
- bad supercharger bearing? (there's 2, BTW)
- bad harmonic balancer?
- downpipe hitting sway bar?

Don't start pulling engines until you look at the obvious.

As far as testing knock sensors, I do not know of any way to test them.. maybe Eddie does, but I will say this. If you over-torque them, even by 1-2 foot/lbs, they are no longer reading accurately. I think the specs are very low... somthing like 12 ft/lbs for the knock sensors.

[Eddie-98GTP]

The only way I know to test knock sensors it to tap on the block near the sensor and watch the scanner. This was the way GM tested them.

But...

Before trying to diagnose a knock sensor problem, the GM text says (which is obvious):

If an engine knock can be heard repair the engine mechanical problem before proceeding with this diagnostic.

[louvered97gtp]

Many thanks once again. I finally got a chance to look at the editor while reading your posts. Here are the last questions I have so I can start playing with the tuner.

Hey Steve.
Also, take a look at the AFR Spark table. this table will add a lot of advance if your commanded AFR drops below 10.7. Even at 11.7, most will add 3* or so.

Which table is this? I see many tables but none matches the description. I found Spark control>, and High octane, low octane, and AFR correction , IAT spark & ECT spark.

....., multiply your MAF table by a number greater than 1. . .... Once you have LTFT averages across the table close to zero, you can get them closer for each MAF cell by multiplying individual MAF cells the same way.

When I multiply the MAF table, Is this the table under Engine>Airflow>Airflow vs Frequency?

Once I had part-throttle fueling good, I increased timing in the part-throttle rpm ranges, and removed timing adjustments from any other table that might change the numbers unexpectedly. There are three tables under Spark Control that should be considered: IAT, ECT, and AFR. You have to either zero these tables out

Can these IAT ECT & AFR be zero'd out for now, and the car be used like this? Can I leave these to adjust down the road when I gain more experienced? Or do these need to get filled back in when the MAF tune is better?

Check your injectors first - if they are not maxing out, then you can add some fuel by increasing the MAF table. Multiply the MAF in the WOT cell ranges only, not the whole table, otherwise you'll mess up the part-throttle tuning you did already. Since you want more fuel, you multiply the MAF cells by a number greater than 1. I usually start with 5% (1.05) and fine-tune from there.

Do stock injectors, 45# and 65# injectors max out at 22g/s? Or are there different numbers I should be looking at for each? Which is the WOT MAF? General airflow>Aiflow vs. Frequency? or Positive/Negative? Or the Main VE Primary button?

- Loose rocker bolts?
- bad supercharger bearing? (there's 2, BTW)
- bad harmonic balancer?
- downpipe hitting sway bar?

Don't start pulling engines until you look at the obvious.

As far as testing knock sensors, I do not know of any way to test them.. maybe Eddie does, but I will say this. If you over-torque them, even by 1-2 foot/lbs, they are no longer reading accurately. I think the specs are very low... somthing like 12 ft/lbs for the knock sensors.

Pulling engines has become quite the norm for me around here lately LOL. I'd rather not have to pull it again, but I will look at the downpipe area. I'll try diagnose the noise I hear first in hopes it's an easier problem to fix.

Have a great and safe new year all

[Eddie-98GTP]

Which table is this? I see many tables but none matches the description. I found Spark control>, and High octane, low octane, and AFR correction , IAT spark & ECT spark.

This would be the AFR Spark Advance Correction - Add table. I would set 11.7 and below to about 3*.

Can these IAT ECT & AFR be zero'd out for now, and the car be used like this? Can I leave these to adjust down the road when I gain more experienced? Or do these need to get filled back in when the MAF tune is better?

You could zero these tables, but I wouldn't raise any of them just yet. If some of them are already negative, I would leave those for now. I don't think this is going to help your problem since these tables should already be 0 in the areas you're having KR (unless the engine is overheating)

Do stock injectors, 45# and 65# injectors max out at 22g/s? Or are there different numbers I should be looking at for each?

Pretty much. You can figure where youare running out of injector by calculating the on time of the injector. If the injector is staying on over 90% of the time, then it's time for a fuel system upgrade of some kind.

Which is the WOT MAF? General airflow>Aiflow vs. Frequency? or Positive/Negative? Or the Main VE Primary button?

You would do this in the MAF Airflow vs. Output Frequency table (I don't have an HPTuner yet, but I looked this up in the help file. I believe this is the right table). The WOT ranges are normally from about 7500 hertz and higher. Again, if your looking for low engine speed/low load KR, this will most likely not help you. If you are running lean at WOT, then this is what you would adjust (among a few other things) to add fuel.

[BlackGS]

I thought I had responded to this post the other day, but somehow it is not here.

When I multiply the MAF table, Is this the table under Engine>Airflow>Airflow vs Frequency?

Yes. The table is under the heading MAF Calibration. The table is made up of cells that represent the airflow for different Hz values of the MAF.

Can these IAT ECT & AFR be zero'd out for now, and the car be used like this? Can I leave these to adjust down the road when I gain more experienced? Or do these need to get filled back in when the MAF tune is better?

AFR Correction - Base: Zero this table out! When you try to adjust timing in higher cells, this table will add even more, which will drive you KR-azy!

IAT Correction - Base: This table adds timing when it is cold outside, and removes timing when it gets very hot. If you have relocated your IAT sensor, you might want to change some values in here. I kept the hot negative timing in there. I figured it is just a little bit of a safety margin.

ECT Correction - Base: This table adds timing when your engine is cold, and removes timing if it gets too hot. I just left this alone. If your engine is running ok, you will be in the zero cells most of the time anyway.

[louvered97gtp]

If your engine is running ok, you will be in the zero cells most of the time anyway.

Sorry to bother you again, what does this mean? Is this related to the histograms? I've read people saying they're in certain cells, ???
I don't mean to be a nuisance, if there's a post you know of that can clarify, please just feel free to link me to any related thread you know of.
Thank you, and Happy New Year!

[Perforator]

It's related to engine coolant temperature. What he is saying is that under normal operating conditions, your engine coolant temperature will operate within the cells that have zero timing added from the ECT Correction table. In other words it's a don't care so just leave it alone.

[BlackGS]

It's related to engine coolant temperature. What he is saying is that under normal operating conditions, your engine coolant temperature will operate within the cells that have zero timing added from the ECT Correction table. In other words it's a don't care so just leave it alone.

Right! The "cells" we are refering to are the table row/column intersections for different values. For instance, in the ECT Spark table, you have Cylinder Airmass across the top and Engine Coolant Temp down the side. When my engine is at normal operating temperature (180* on my setup), all the cells for that table row are zero. Therefore, I would neither add nor subtract timing when my engine is running at that temp, which is almost all the time.