So I have started to log/modify a few things on my basically stock 2002 ls1 camaro. (only has an slp lid)

I went for a drive tonight and noticed that I was getting some knock when I looked at the scans afterwords.

Now, this is a stock tune aside from the transmission tables I have modified. So this is why I am stumped- When I get KR, my car is adding timing? Since when does the pcm command to add timing when it see's a kr condition? Any other car I have tuned pulls timing?

2ndly, is it common for these cars to have kr stock?

3rdly, when I look at the tune, it looks like I am only supposed to be commanding 19* at WOT, yet, the scans seem to show up to 25*...how is that possible??

I've uploaded my tune and the scan, seems like I can't upload my cfg file.

since the scan is pretty long, anyone that looks at it, here are some areas I suggest looking at:

7.13.937
9.11.969
10.44.594
11.02 is when I go for a long WOT blast with zero KR
13.03.812
16.01.984

Anyone have any explanations?

 

It's not adding timing
The timing in your datalogs seems to be advancing because you release the throttle most of the times. Light throttle= more timing advance

Your wideband doesn't seem to be operating correctly because it's pegged at 12.84 all the time. The O2 give lean readings when the knock retard occurs, so it may be one of your problems.

 

Forgot to mention, don't look at the Wideband numbers, there is no wideband hooked up to this car.

I know that the car adds timing when you let off the throttle, but in all the instances that I mentioed above (where I gave the time stamps) I was on the throttle and not letting off.

 

Lets see
@ WOT, 6000 RPM and 0.68 g/cyl your main high octane table has 25°, not 19 like you think, so it's correct.


7.13.812
2.9° KR
Your high octane table is commanding 27° @ 1800 RPM, 0.48 g/cyl
The hystogram 1 also records the same 27°, the final advance you get is 23° so it isn't adding any timing. You can check the next points of the datalog and you will find the final advance will be less than your timing tables.

9.11.969
2.6° KR
Your HO timing table has 20° @ 1400 RPM, 0.52 g/cyl, after interpolation and some adders you aren't logging the commanded spark goes to 27°, the final spark advance is 20.5° so it didn't add any timing

10.44.484
1.1° KR
High octane table has 25° @ 2400RPM, 0.56 g/cyl. After interpolation and adders total advance is 23°, but the final advance is 21°. again, no timing was added

13.03.812
1.7° KR
HO table has 23° @ 4400 RPM and 0.68g/cyl. Total advance is 19° and the final advance you get is 18°, no added timing

We can check more points but this gives you an idea.
Timing advance is calculated from main tables using interpolation, if your tables have big differences between one cell and the next it causes erratic timing advance.
Then the timing goes thru the adders and multipliers, some of them add timing some pull timing.
Torque management and traction control also pull timing
After every correction is made, the final advance is applied. If no knock retard is detected, timing is applied steadily. If knock is present, the PCM will pull as many degrees as it calculates, but the final advance will never be greater than the total advance calculated from tables and adders.

It may seem to you like timing is being added, but it's not. You need to datalog more spark PIDs to know what's really happening

 

Interesting, I thought 1.00 g/cyl was WOT cells. I've been looking at my v6 tables too much!!

Still, I would think that if it was pulling timing I wouldn't be watching it climb from 19.0, 19.5*, 20.0*, etc. It seems to keep going up, when it should be going down?

The spark tables are all stock to my knowledge. Unless the previous owner changed something, but I highly doubt it, everything on this car was stock when I got it, including the air filter...

I just halfed the tq mangement right before this log, and TC was turned off while I was logging

 

If you are showing 0.68 g/cyl at WOT, that's low and you
may have an air mass fidelity problem (crusty MAF?) that
gives you short fueling and extra advance.

Or, your intake tract just sucks. But for it to be consistently
that low (same at 4400?) says probably not just restriction.

 

explain?

When I had the maf off to put the SLP lid on, everything looked clean to me?

only thing done to the car is the free ram air mod, and an slp lid/k&N filter (I really don't consider these things worthy of even being mentioned as mods)

what do you think could be the cause? Mechanically the car is in or appears to be in great shape.

Is it possible to have failing maf that is starting to read low?

 

I think it may be a bad MAF, because the entire WOT pull the intake pressure stays at 99 KPa or higher. At sealevel MAP readings at WOT are like 101 KPa so 99 is very good (I only get 84 KPa @ 5000 ft altitude).
If the intake tract, filter or anything was restrictive the MAP reading would be lower.

OP, what are your MAP readings with key open, engine off?

 

I'll look tonight and let you know.

Question though- should the car not run poorly if the maf is going bad?

I have a spare lt1 maf sitting here anyways I could toss on, but I can't calibrate it until I get my wideband put on this car

 

the mafs are the same

 

So Key on engine off I am reading 101.0 kpa. That is after I drove it home for about 15 minutes, shut the car off, plugged the scanner in and turned the key to on only.

With the engine running I am reading 35.0 kpa I believe it was.

I could be wrong, but when I was doing research on them, I believe the LT1 maf flows more as I believe the 3.8 turbo guys look more so for the LT1 mafs than they do the LS1's. I could be wrong, but that is what I remember.

 

You don't need a wideband to know it's running lean in this case. Have a look at the O2 mv at WOT. They're switching low from 4000 rpm up. AFR up there is probably 15-16. Could either be low fuel pressure or a bad maf.

The airflow numbers (260-270 g/s at peak) are a bit on the low side at sea level, I get about the same at 2000 ft. But your stock exhaust might just be choking it a bit. I'd check the fuel pressure under load before swapping the maf unless you can swap for a known good one to check.

Also, the part throttle KR looks fairly normal and I wouldn't worry about it too much. Probably mostly false knock.

 

so throw this into the mix of things. Im looking at the scans a little further-

at 6000rpm where I am showing lean on the narrowbands, I am at 87% injector duty- could a bad maf cause that or only a fuel pressure issue?

all lean instances seem to occur at 4600rpm and above. If it is infact a fuel pressure issue, what would cause an issue that seems to only consistently appear from 4600rpm up?

I would think if it was an issue with the fuel pump, it would not only occur intermittently at those exact conditions everytime?

 

A bad MAF won't cause the injector duty to climb
You have a bad pump and/or a clogged filter, replace both and retune

The only way to know for sure is to hook a fuel pressure gauge to the rail and tape it to the windshield in a place you can watch it when you go WOT. If the pump is bad or the filter is clogged the pressure will fall several PSI bellow 58

The pressure should stay at 58 psi all the time you're at WOT

 

Fuel pressure problems become most apparent at high rpm because the fuel demand increases (roughly, peak airflow = peak fuel flow = peak power). At an injector duty of 87% a stock motor should have plenty of fuel if the fuel system is holding up. I see about 83% at similar air flows, which gives me about 12.7:1 AFR. So your maf is probably ok.

I'd copy the low octane spark table to the high octane untill it's fixed to prevent knock, and avoid WOT except for testing.

 

I would think 87% injector duty on a stock LS1 is high is it not? Especially because generally you do not want to exceed 80%...I know on a stock 6 it is in the 60's irrc.

Here is something that throws me for a loop seeing as it shows lean. Being that lean I would think that I would be popping and bucking at WOT, yet the car runs beautiful and pulls great. In fact, my modded 3.8 would walk away from the LS1 from 0-60mph, but this LS1 would walk away from my heads/cam 3.8 from 60mph +

The car pulls hard on the highway when you get on it, so this shouldnt be the case if I was lean? (I have gone 14-15 afr lean in the 3.8 before and you knew it)

So I know I anything from this point forward is speculation until I can get a fuel pressure gauge on it, but are you all sure that the MAF readings are not referenced to for fueling/injector duty?

Because these are my thoughts:

1) You mentioned my MAF readings seemed low
2) Even if I had poor fuel pressure, the car still revs up to 6000rpm before shifting, so poor fueling would not put me at lower g/cyl?? g/cyl has to do with the air coming in, not the amount of fuel corresponding
3) I know that you mention the most strain on the fuel system is at peak power- but the MAF is also highly referenced from what I understand from 4000rpm +, which is right around when the narrow bands read lean.

I only throw all of this out there because literally the only way I stumbled onto this issue was hooking hp tuners up to the car for some base scans. I had zero issues that prompted me to hook up the scanner in the first place.

 

update, I swapped in the LT1 Maf and copied the Low octane tables over- still runs the same, up to 4* kr at 4300rpm and 48/52 mv on the narrowbands.

DA tonight is 928

I'll head to the shop hopefully tomorrow and get the fuel filter changed out.

Still boggles my mind that I would have no idea there is an issue had I never plugged in the scanner.

 

If you're going into PE mode during this KR you need to change your PE Delay. That is retarded to have it that high. Try setting it to 0 then punch it. This will allow you to go into PE once your TPS threshold is met. Or put it to stock which is probably 800 rpm.

Change this too

Fuel -> OL & CL -> EQ ratio

All cells from 140* to 212*, change to 1.00

I would turn on STFT to help maintain stoich while in closed loop


I'm no tuner pro or even novice. I just play one on the internet.

 

The tune is bone stock with the exception of tq management has been halved, and some transmission parameters modified, and tire size adjusted.

All pe tables and enables are factory. I refuse to touch any of those tables without a wideband installed.

 

I just pulled a few stock ones and I don't know why it's that high for stock. Maybe someone with more knowledge can chime in. I checked my stock file and it's also set at 5,500. But my factory tune AFR Stoich is 14.68 where yours is at 14.62. Everyone I know puts it to 800 rpm or less to avoid another parameter that needs to be set in order to enter PE.

I personally wouldn't tune without a wideband but lowering that PE Delay will help keep you richer during WOT. Your stock tune from the factory is rich to say the least since it's commanding a 11.4 at peak TQ and HP.