Hel!p look at this log please ( Cammed 5.3 truck)

[Slowrc]

This is a log of a cammed 5.3 . Recent mods include a 4.8 to 5.3 swap, 3k converter, shift kit, and some tuning. Look at the rpm on the 1 -2 shift. The owner complains of a sluggish off the line condition and says it just soes not pull as strong as it use to and now he has more cubes. I have not logged the off the line condition because thats at the track only. Still spins on the street. Any ideas? I'll save mine till someone hits on it. Thanks.

[5.7ute]

Why is it only commanding an AFR of 14.63 under WOT conditions? That and high timing for a that mix wouldnt be helping at all.

[5.7ute]

That lean spike at frame 463 could well be a detonation issue not being picked up by the knock sensors.
Do you have any logs of the previous combo. Trans or convertor issues I wouldnt think would affect both rpm & mph, unless the trans was loading up internally. Was the car frying the tyres in this area?

[joecar]

+1... I agree with Mick... needs to command richer at load/WOT and with less timing...

Even if you don't hear knock/detonation, combustion chamber temps would be going very high (which may cause damage and greatly increases knock/damage potential).

You need to richen CFOL and PE... and make sure PE enables...

Also, being too lean may be the reason why it may be sluggish.

Looks like you're running OLSD (no MAF, no LTFT)... and have gotten BEN's close to converging...

Lean spike might be knock, but not for 7 seconds... that might be the wideband resetting itself or something.

30° timing advance thru peak torque is too much advance... if you don't hear it knocking then the other problem is cylinder pressure would be peaking a bit early (i.e. piston-rod angle is not at optimum angle to make the best torque... i.e. piston is still too close to TDC where it is not moving down very much yet).

My understanding of the LS1 family cylinder heads is that they are a fast-burn design, so you don't need as much timing advance.

$0.02.

[5.7ute]

I was just looking at the spike at frame 463.
Joe, what do you make of the drop in RPM & mph from 410 to 430.

[5.7ute]

Also I just noticed it is either an arctic winter, or the IAT sensor is an open circuit or not plugged in.(Reading -39deg C)

[joecar]

The other problem you have is the IAT pid is pegged at -38°F like Mick said... the IAT sensor might be disconnected;

(my comment on this is that at -38°F I would have expected the commanded AFR to be much richer, something like 11.7-12.5).

[5.7ute]

Joe, I believe it is a custom OS with stoich commanded. Wideband AFR is fluctuating like STFT are active.

[joecar]

I was just looking at the spike at frame 463.Ah, I see it, yes maybe it's due to knock...


Joe, what do you make of the drop in RPM & mph from 410 to 430.That looks maybe like his spinning tires are slowly/progressively gaining traction and at the same time the engine is starting to experience increasing load (from increasing traction and insufficient torque).

[joecar]

Joe, I believe it is a custom OS with stoich commanded. Wideband AFR is fluctuating like STFT are active.Ah, I see that too, now.

[5.7ute]

That looks maybe like his spinning tires are slowly/progressively gaining traction and at the same time the engine is starting to experience increasing load (from increasing traction and insufficient torque).

Yeah, that's what I started thinking after a closer look.

[joecar]

Slowrc, what are the cam specs...?

[Slowrc]

Sorry to come back so late. the cam is a 220 56x lift on a 112. this log was taken while doing autove. I will post the tune later today. I am at work now and can't do it on the work computer. It does spin on the 1-2 shift. I thought commanded would be 12.95 for fuel so I'll have to check into that and thats the timing table from a well known local tuner from the 4.8 tune. I definitely see you guys points! Thanks for looking.

[Slowrc]

Could the IAT have made the commanded A/f be that high? on my tune its 12.95 just like the autove tutorial says. I texted the owner the schematic and he got the right wires back installed. The wrong ground was pulled when we diabled the maf (DOH!) He says it idles soo much better now. THANKS!!!

[joecar]

I looked at some tune files, there is no IAT AFR table other than B3641 IAT PE multiplier (which I saw was zero in all cases)...

So IAT does not affect the commanded IAT (unless B3641 is non-zero during PE)...

But IAT affects the airmass calculation... IAT -38°F would cause a greater airmass to be calculated, so for a given commanded AFR this would cause a greater fuelmass to be injected, the fuelmass would be greater than what is required to meet the AFR with the actual airmass (at actual intake air temp, 70°-90°F or so), so wideband will read richer than commanded AFR.

Edit: my explanation was messed up.

[Slowrc]

I will log and tune the fuel map a few more times and see how it looks. Was the iat affecting the timing? max timing on the high side of the map is 28 in the tune.

Also, how is timing calculated if I am running SD?

When should you perform a full reflash instead of program with currently loaded calibration?

THANKS!!!

[joecar]

Post #15: I had messed up my grammar/context/participles/something... :doh2: see my correction to make it read properly.

[5.7ute]

Slowrc. Do not continue trying to do AutoVE until you have changed B3647 away from stoich in the low load areas.(I use 14.5:1) STFT are active when you command stoich & will mess with your data.
Timing is calculated from cylinder airmass. Log GM.DYNCYLAIR_DMA & RPM to reference what cell you are in.

[swingtan]

Here are my views / observations, most are repeats....


The tune appears to be a CLSD, evidenced by the WB signal hunting at light throttle.
PE mode is being entered, evidenced by the WB signal varying in high load areas.
As already mentioned and fixed, the IAT was not working.
Broken IAT sensor will mess up all VE correction data due to charge blending and if using a COS, {A0014} IAT VE Multiplier. Do not use any log with the bad IAT sensor foe VE correction!
Log frames from 408-430 is most likely wheel spin, evidenced by the sharp rise in VSS at the gear change followed by the gradual down slope to a speed very close to the pre gear shift value. I'd guess that the vehicle was on dirt or wet pavement or just has bad tires.....
It appears all torque reduction has been turned off for the 1-2 shift, but the rest of the up-shifts still have some.
The timing is too high and the commanded fuel is too low. This will make the car feel very weak at WOT, most likely it's also experiencing a bit of exhaust backfire as well.


Now, what to do moving forward...


Fix the IAT and confirm it is reading correctly! ( already done )
Confirm the PE tables to ensure a more reasonable amount of fuel is commanded during PE mode. Aim for 12.5 while doing the VE so it's always going to be safe.
Alter max spark timing in PE mode to around 22' while dialing the VE.
If using a COS, command 14.5 in all cells in B3647 to force the PCM into OL mode. Otherwise use BiDi's to force OL mode. You don't want CL mode when doing the VE
Disable DFCO when doing the VE corrections.


This should get you to a much better position and wake the car up a lot.

Simon.

[Slowrc]

The first tune is the tune used while I was making the log that was posted. This is a truck with 4:56 gears and a shift kit. It does break loose on the 1-2 shift. The second tune is some changes that have been made since the first tune.

I see that 3618 is set to 14.62, but isn't that the way I was instructed in the autove tutorial?? Why was it not using the richer 3605 that would have had the commanded @ 12.95?

I don't have 3467 in this OS.

Thanks so much for helping!!!

[voda1]

Downloaded the log file but when opened only shows 3 pids selected - BEN1, INJDC1, INJDC2. Using v7.5.6 build 117 in demo mode.

[WeathermanShawn]

Looks like it using B3648 as Commanded Fuel???

You oscillate between 14.63 and 14.68 AFR. Thats the only Table I see that would do that..

[joecar]

Some comments:

I know the AutoVE tutorial says to set B3618 to stoich (and to make the high load columns of B3605/B3647 sufficiently rich)... the reason for this was to avoid any sudden transitions in commanded AFR...

in this situation (AutoVE), the earlier LS1B PCMs (LS1 F/Y cars) selected the AFR from B3605/B3647 since these are richer than B3618 (when PE enables).

If you're not seeing this happen, then set B3618 equal to the WOT AFR in B3605/B3647 (all cells in B3618 including the low rpm cells... e.g. consider what happens if engine is turning 1200 rpm and you mash the throttle...?)

Also, let PE enable easier by setting B3616 to 60% below 3500 rpm, and to 40% above 3500 rpm.

[Slowrc]

Thanks guys! The truck is running much better now with the IAT back in action. I will look in to those changes and make sure I am going richer in the high load areas. Thanks again!