Thread: Interpreting scan logs, any help please?

OK, I'm pretty sure I've worked out the mechanical bugs. Car is drivable. Went for a short drive tonight so I can begin trying to figure out these scan logs. I am not hammering the throttle, just rolling into it. Not going much over 65% tp. That's because I'm seeing kr. It happens when MAF frequency hits about 8000. My ltft is around -1.5. Stft -5. KR is up to 5-6. Well, I'll post a log if anyone is interested, but basically I'm wanting to know how I relate these points to the spark table? The spark is in Mg/cylinder. And MAF is in hz. Is there a formula to figure out what points I should be pulling spark?

Right now I'm using the L67 spark table. I imagine I'll need to trim some spark since I'm running more compression. Just don't know how to find the points in the spark table to pull. I googled and found a formula, but its for a v8.

I have tried using Jerry's guide to tune ve first. But my car won't run with the MAF unplugged. As soon as I hit boost the car dies. No idea why this is.

Here is the log if anyone has time to look. Around line 1200 was one problem area.

https://www.dropbox.com/s/ulyhzb785z...1scan.xml?dl=0

The VE table on a supercharged PCM stops at 140 kpa, not even really 4-5 psi of boost, the car is not meant to use the VE table.

It takes everything from the MAF sensor and MAP sensor.

I have no idea what that is in the dropbox, I use hpt so I don't know anything aobut dhp if that what that was.

Sorry, that was an xml.

Here.

https://www.dropbox.com/s/ft59ezqo0s...1scan.csv?dl=0

Originally Posted by Fivefingerdeathpunch

The VE table on a supercharged PCM stops at 140 kpa, not even really 4-5 psi of boost, the car is not meant to use the VE table.

It takes everything from the MAF sensor and MAP sensor.

I have no idea what that is in the dropbox, I use hpt so I don't know anything aobut dhp if that what that was.

It's as soon as I hit boost, 100 kpa it just dies like i turned the key off. Have to let it sit for 15 seconds before it will start. Dunno if it's flooding or what.

The ADC input 2 is my wideband. I got the formula working but it stops responding after a couple minutes. Need to get ahold of AVT and see what's going on.

Originally Posted by SgtMarshal

I looked at it, I am too much of a noob tuner to make any real suggestions, other than your fuel trims need a lot of work

Lol, thanks Captain Obvious

If you are running a 3.4 pulley that is too much for a top swap. I need to be on E85 in order to run that pulley.

And just to double check, you are using an L67 MAP and tune right? I dont think the L36 tunes like to see boost.

Third, what is that A/F column? commanded Air/fuel? because every time it drops to <14.7 is when it starts to knock. I can't tell if this is the cause or an effect.

Originally Posted by JoRoW99

If you are running a 3.4 pulley that is too much for a top swap. I need to be on E85 in order to run that pulley.

And just to double check, you are using an L67 MAP and tune right? I dont think the L36 tunes like to see boost.

Third, what is that A/F column? commanded Air/fuel? because every time it drops to <14.7 is when it starts to knock. I can't tell if this is the cause or an effect.

You have identical setup. I can get a bigger pulley, but I'm going e85 too. Was just trying to get something drivable for a tank or two of 93. Gives me a chance to figure some of this tuning out.

Yes I have l67 map and tune. The A/F column is commanded I think. DHP is not liking my WB for some reason.

I just had an aha moment. Not sure if its right. But what I could do is look at the spark advance and use that to figure where I need to pull timing in the table.

MAF Decade Average of KR Average of LTFT Average of Injector PW Average of MAP(kPa) Average of O2
0 0 2.34375 2.782110039 98.97674419 4.239069767
1 0 2.34375 3.207446403 95.6 4.34
2 0 9.095982143 2.360037505 45.05791506 429.5427027
3 0.003202492 4.235197368 3.129520369 50.99595142 488.8561943
4 0.013090093 -3.607047872 4.158786897 59.5106383 491.5588652
5 0.090921336 -4.579741379 5.791851156 74.4137931 537.3368966
6 0.289667694 -5.094630282 7.378059461 91.42253521 536.9374648
7 0.82108347 -3.700657895 10.27494348 117.4473684 591.7247368
8 3.598632813 -0.607638889 13.96709138 136.2222222 911.6411111

Your trims are very lean at idle and cruise (MAF decades 2 and 3). When you start getting into load (MAF decades 4 and up) at throttle tip-in, you are weak in the PE transition and get the KR. Look at your frames in the 250 - 260 range. Your LTFT shoots up to 10% because you can't keep up the fuel. You need to richen up the MAF curve in the lower ranges and check your PE transition throttle settings, and then adjust PE fueling for added richening.

Thanks guys! I may have some bad data though. I found another exhaust leak pre o2 sensor. Could that be why the trims go way high especially on decel? A few times my car also died when I slowed to stop. I aimed a leaf blower at the exhaust and found a nice one where the crossover connects to the rear header. I'm gonna let the rtv set and take it for another drive later.

Sorry, feel like I kinda wasted your time. I'll make sure its not leaking before I post another log.

A trick I used to find exhaust leaks was to put a rag or something in one of the tailpipes and then seafoam if. the white smoke will come out of the leak.

Originally Posted by JoRoW99

A trick I used to find exhaust leaks was to put a rag or something in one of the tailpipes and then seafoam if. the white smoke will come out of the leak.

That's a good trick. I'll remember that. Tough to do the rag trick when you're alone though. Used the vac because I wanted to get working without waiting for pipes to cool.

Originally Posted by mguzzo

Your trims are very lean at idle and cruise (MAF decades 2 and 3). When you start getting into load (MAF decades 4 and up) at throttle tip-in, you are weak in the PE transition and get the KR. Look at your frames in the 250 - 260 range. Your LTFT shoots up to 10% because you can't keep up the fuel. You need to richen up the MAF curve in the lower ranges and check your PE transition throttle settings, and then adjust PE fueling for added richening.

Could this be because my IFR is off? Stock L36 IFR is one value in the whole table. The L67 IFR is scaled down the list. I've seen both methods used in topswaps. Mine are scaled starting at 219 something.

First problem I see, beside the obvious LTFT's needing fixed, is that when you're in boost, you're still not in PE and your afr is at 14.7. Under PE_Enable_TPS, it should be set to whatever tp% you start getting into boost at. Looking at your scan, that's just over 30%, I have mine set at 35%. It looks like you're not seeing PE until 50% throttle, and even then a commanded 13.1-13.0 afr is too lean. Any way you could add your .bin to the dropbox so we could take a look at it?

Sure, thanks. Here is the bin. I get what you are saying. How exactly do you tell when i'm in PE looking at the scans? Is it when the AFR changes? So, when just cruising the car is using MAF table, but when I step on the throttle, PE table is used once TPS reaches the set value?

Yeah, you can tell you're in PE when your AFR changes, looks to be right about 50% for you, but you start seeing boost at ~30%. Gonna take a look at your .bin.