Need help for tuning fuel/advance on new 418 LS3

[JimMueller]

Replaced a 377 LS3 with a 418 LS3, static compression went from 10.7 to 11.9. DCR is about 8.8. Using premium fuel. Using new NGK TR6 plugs, unmodified gap. The passenger side cat seemed a little clogged when the engine was out, the driver side looked okay.

We're encountering some challenges tuning the new motor, I'm at the shop now. I've not gotten my NGK AFX lambda error config working again in V4, it worked previously in 2.24. Thus for fueling I'm using LTFT+STFT to adjust VE & MAF. But I didn't get very far, it seems to want to ping excessively even after LT+ST shows near 0 or rich. Maybe I just haven't spent enough time on it? The old 377 calibration had the misfire tables desensitized, I put them back to stock for the 418 calibration. I am getting some misfire codes, and ironically all the P0351-P0359 coil codes are also set, wondering what would cause all of them to set simultaneously.




Any guidance is appreciated.

[JimMueller]

The shop is blaming the excess knock retard on the back pressure caused by clogged cats, due to the amount of oil that got past the rings on the old motor. He’s able to hold his hand on the post-cat pipes, but not on the pre-cat pipes, indicating post cat tubing is not getting nearly as hot

He took out the spare bung cap on the passenger collector and claims when driving he’s hearing a lot of popping coming out that hole because it’s backed up; he said the popping wouldn’t be that bad even if it was too rich. Going to get the cats replaced with a straight pipe tomorrow. Not taking it home today, he’s worried about engine health if I drive it. Cha-ching.

He found a somewhat loose ground on the back of the head that he tightened, the dash gauges did not exhibit the same behavior on the only test drive since that was tightened.

[Jeff7577]

Let us know how it goes but I wouldn't put much faith in a shop that doesn't have a backpressure gauge or thermometer. Does it have the 99+ knock sensors and harness? Could it be induced from the exhaust hitting something? It looks like the KR comes out of nowhere and for no reason sometimes, like cruising around 1600 without moving the throttle it hit almost 4 degrees.

[Russ K]

For the Lambda error to function, just select the EQ Ratio Error in the Maths Folder. As for the spark knock, you will need to use 93/94 octane fuel.

Also your engine temp is very hot. Use a 160*F thermostat & lower the fan temps. And check for any blockage of the radiator

As for all the coil DTC's, they all share the same G114 ground circuit that's located at the rear of the left cylinder head. Is that the same loose ground that was tightened?

Russ Kemp

[JimMueller]

It's a '98 F-body with a LS3, using an extension harness to connect the knock sensors on the sides of the block to the factory harness. I'm pretty sure they are the '98 sensors, same ones that seemed to be working okay with the prior engine.

Where are you seeing the engine temp concern? Usually the ECT is near 200*F, and it pegged in the 2-teens at the start of a couple of the logs but quickly fell to 200*. The IAT's are definitely hot, using OEM IAT location in lid (same as prior engine). It took a lot of driving to get the IAT down to a reasonable 100*F.

He didn't specify which ground on the back of which head that he tightened. Would that also affect the oil pressure gauge? They previously had an oil pressure gauge problem on the OEM dash but the mechanical gauge said the pressure was fine, they said the fix for the oil pressure flakiness was repairing the oil pressure sender ground wire.

For Lambda error, the math entry references EQ Ratio & EQ Ratio Commanded. When I search PIDs for 'EQ', I see "EQ Ratio Commanded" but I do not see 'EQ ratio'; I also see AEM/Innovate/PLX - EQ Ratio. Don't I need to have both PIDs from the math formula listed in the channels?

If the knock problem persists, I'm asking them to increase the octane and re-test.

[JimMueller]

Replacing the cats with straight pipes eliminated all the knock, they must have been partially blocked and causing too much back pressure. A/C was charged but not blowing from vent, noticed my HVAC tube wasn't plumbed in behind the intake manifold. Performed smoke test and fixed any vacuum leaks. Fueling is getting better using the Greg Banish VE config (haven't started idle or MAF changes yet), but getting the car started I often need to blip the throttle a few times before it'll idle on it's own, damn embarrassing. I haven't fiddled with this stuff in the better part of a decade, how close do I need to get the VE before I can begin with the the RAF logging? The attached is a quick hand smoothed version of the VE but it's not as close as I want it yet, and I've only gotten up to roughly the 3600RPM column, a little higher in the WOT rows

TPS voltage key on, engine off, currently 0.63V
TPS voltage at key on, engine off, currently 4.59V
TPS % key on, engine off, no throttle input, generally 0.0%, sometimes bounces to 0.39%
TPS % key on, engine off, WOT, 100%
IAC, engine hot, I want these to be about 40-75 IIRC?

I'll try adding a filter on the RAF graph to only include TPS% < 1

[JimMueller]

Because I couldn't get the car to idle without throttle at at 80*F ECT, I raised the the RAF (which was probably too much) 10g/s across the board. It idled without throttle, but I heard a lot of whistling from the front of the filter and I couldn't get the IAC's to drop below 160 by adjusting the throttle blade. Should I reduce that RAF and try again? This is the current tune with the extra 10g/s.

[JimMueller]

With the help from a friend on LS1Tech, we've gotten the idle stable enough to not cause grief during the fuel tuning, the IAC's are in the 50-60 range with the idle voltage at .67V. He says I might set a code if we go to .69V, and he'd prefer to have the IAC's closer to 30 at warm idle because of the cam. That would mean drilling a 1/8" hole in the blade. Other takeaways from where we've left idle for now:

* The Dynamic Airflow is about 3g/s higher than Desired Airflow
* On throttle blip, it hangs a few hundred RPM high for about 8s before settling to idle RPM
* Idle will hang until we calibrate the IAC
* Hole drilling should theoretically happen before IAC calibration, but hole will increase negative idle trims, which we can control by shifting the IAC table

Is there a consensus on my desired IAC position vs a permanent drilling change? I seem to recall the goal was never to drill unless absolutely necessary.

Edit: Here's the current tune and the 'cold' startup log from this morning, it's about as cool as it'll get from sitting overnight. I forced the fans off until it spent a few seconds above 230*F. When I set the set screw last night, I set it to .67V, as close to .69V as I could without hitting .69V. Last night the IAC's were in the 50-60 range at warm idle without turning off fans. This log shows that it's spending most of it's time at .65V, is that expected? Should I adjust the set screw again?

On the RAF, do I want to use the average DynAir, or the DesiredAir, to populate the cells? I used to use DesiredAirflow, but recently I've heard discussion about using DynAir?

[cobaltssoverbooster]

have you drilled the nub off the tps sensor and opened the screw holes a tad to allow it to rotate and be adjusted further?

[JimMueller]

I believe the TPS I have right now has the nubs removed and each hole is slightly slotted. Refresh my memory on how I adjust the TPS sensor after I slot the holes? If I rotate the sensor so the tps voltage changes from say .65-.67 to something lower, then that allows me to adjust the set screw to add more voltage back up to .67 which adds more air to lower the IAC counts further, am I remembering that correctly?

[cobaltssoverbooster]

adjustment is easy if you have a mechanical tb unit. monitor tps voltage and use the manual stop adjuster to open the blade by .01-.02 volts at a time.
once the mechanical change has been made loosen the screws and return the tps voltage to the setting you had before.
unplug the tps unit, turn ignition on without engine for 30 seconds or so, turn off ignition, plug sensor back in, turn engine on.

monitor new iac count position after settling and make any further adjustments as needed. you can also watch tps % to verify you still achieve 100% tps at wot.

[blindsquirrel]

Holes in TB blades are super easy to plug with lead shot. Install it like a Ye Olde Timey hot rivet - Put a small chamfer on both sides of the hole so the lead forms a flange and can't fall out either direction. Clamp a suitable something in a vise to act as a backup and then hammer the lead ball flat.

[JimMueller]

If I rotate the sensor, will that cause the WOT TPS voltage to increase as well? There are limits to the lower & upper TPS voltages that I need to stay within to avoid problems, right?

I'm reading conflicting opinions on whether to use Desired Airflow or Dynamic Air to populate the RAF table... if they are a few grams different, why would I choose one over the other?

[cobaltssoverbooster]

because the blade is physically opened you have reduced its range of total travel. This means when its adjusted you should see a properly calibrated idle voltage and a minor reduction in wot voltage due to the reduced travel range. thats why i recommend watching the tps % post adjustment to verify you still have 100% tps reading in the ecu.

[JimMueller]

This is interesting... version 4.4.2. Channel listing says MAF Hz is 6735, but the graph has the 6000 column highlighted. It's not the first quirky thing I've seen in this scanner.

GraphDiscrepancy.JPG

[JimMueller]

I've noticed that the g/s is consistently higher (by about 50-60g/s near 8000Hz) in the old 377ci MAF table than it is with the new 418ci MAF table. The only thing that changed in front of the intake manifold was removing the Saxon honeycomb filter, because I read that with the LS3 slot card MAF there is not a benefit to the filter. I would expect the additional torque of the motor would require higher g/s at the same MAF frequency. Could the filter be the source of such a discrepancy? Something else?

[JimMueller]

I decided to re-install the Saxon filter back in front of the MAF. While doing so I found that the shop that put the motor back in the car over tightened the clamp on the lid neck and now I've got a "V" (sort of like PacMan with a small mouth) on the inside of the lid neck, inline with the MAF card. I tried to clean that up the best I could but it looks like I need to buy another lid. Still tuning MAF only, didn't complete VE yet.

I also installed a new NTK 24302 for my NGK AFX today. I connected it to the power harness, turned on the power and let it dangle in free air for 20 minutes, then adjusted controller to Cal-, then disconnected power, then disconnected from harness temporarily to install the new sensor in the bung, then reconnected harness. Driving afterwards it was showing rich compared to the old sensor (13.x vs 14.x). On the same drive, I noticed it went WAY rich (9.x). When I parked, I noticed my engine sensor fuse had blown (O2s, MAF, reverse lockout, skip shift solenoid).

A new fuse blew within a few minutes of driving and it was driving like ass. So I took a chance and hard failed the MAF by physically disconnecting the harness, then loading the VE-only tune. Driving around on it wasn't bad, but the AFX was still reading even richer (10.x) whereas it had not when I stopped tuning VE before (then there was no airflow straightener and the old NTK sensor). So I assumed the old wideband sensor had led me astray and I started removing fuel from the VE table table using paste special multiply. Man, it's sure asking me to remove a lot of fuel, can you tune VE with the engine sensor fuse dead?

[JimMueller]

WTF? Wondering if I accidentally moved the calibration dial on the AFX, I recalibrated my sensor again today...I checked it at 45min and the battery had died. Recharged battery and re-checked, still at the Cal- setting. Drove it to the store tonight without the scanner, it was bucking and sputtering all over the place, controller showing 16.0 on the LED. It was showing excessively rich yesterday, so I was taking out the desired fuel, now it shows lean today. Could it be the controller itself? Might this have anything to do with the engine sensor fuse being blown? Looking at a years old thread here, it looks like I was able to tune VE in the past with the same fuse blown.

[JimMueller]

Should Copy with Axis from the Primary VE table and pasting to the Secondary table still work in 4.4.2? It seems to be pasting into the wrong rows in the secondary, specifically it's off one row.