All
Is it normal for these engines to have RPM dip when coming to a stop ( manual trans, clutch in ). My engine idles around 950-975 but in the run I just did it would dip to 600-700 rpm then recover. Just wondering if this is expected or can be tuned out ?
Log-0000-19258269 ls376 r8.hpl
thanks!
not normal
Nope
JTC Performance - Authorized HP Tuners Reseller
Remote performance tuning
Post a toon and what is done to the car if you want help. -5 degrees on a coastdown is a little excessive lol
TuneOriginally Posted by ns158sl
stock-runningcooler-highermapcheck.hpt
Latest log
Log-0000-19258269 ls376 r8.hpl
Engine has less than 50 miles on it. Test runs around town its stalling at stop lights after getting warmed up.
Engine specs are:
DESCRIPTION:
HP & Torque: 625 HP / 565 FT LBS
Compression Ratio: 11:1
Aluminum Heads
Hydraulic Roller Cam
Forged Crank
Forged Pistons
BLOCK:
OEM Block Machined in the USA!
6-Bolt Main
4.060" Bored to 4.069
1-Piece Rear Main Seal
ROTATING ASSEMBLY:
New Forged Crankshaft
4.125" stroke
Forged 6.125" connecting rods
Forged Pistons
Internal
CYLINDER HEADS:
BluePrint Aluminum Cylinder Heads -PS8015
72cc chamber
2.165" intake/1.600" exhaust valves
259cc intake/102cc exhaust runners
CAM SPECS:
Roller
.624 intake .624 exhaust lift
239 intake 255 exhaust duration
@ .050, 114-degree lobe sep.
Replace those sae channels if you can. The polling rate is not helpful
Yeah I think he is logging without a laptop.
Guys. That was logging using the mpvi3 interface while driving. Is that log no good?
Add Cylinder Airmass, Volumetric Efficiency, Dynamic Airflow, MAF Sensor, Injector Duty %, Injector Pulsewidth B1 & B2. That should get you some usable data. Get rid of the throttle channels except Commanded; keep that one.
You can try this tune to see if it helps with the dip when coming to a stop.
ls376 r8.hpt
Thanks LS Rob. I'll load that up in the morning and change the logging settings too
@LS ROB here's a log from running the car in the garage after making the changes you suggested. Do you think it looks better ?
garage-idle-after-lsrob.hpl
Here's the log from the MPVI3 device with the requested channels added. I was driving around the street like I did yesterday. It seemed better to me but hopefully the logs show something better too ?
Log-0002-19258269 ls376 r8.hpl
Any help is greatly appreciated!
My goodness! That second log is slower than USPS right now! However you were logging the idle log in the garage; do that and replace those (SAE) channels with one similar like hjtrbo said. You may need to update your Engine size and verify your injector part number before going any further. I thought I seen somewhere you have 42lb injectors? Need to verify the data for those. Is this a ls3 based 427 or 429? Wondering why that wasn't updated if so. Once you verify the part # on the injector, post it up so someone can make sure your data is correct. That's the foundation for the tune.
Thanks LS ROB. Updating those channels on the mpvi3 device is an interesting process. I downloaded defaults first, saved the XML file. Made the changes to the channels in VCM Scanner then saved those channels. Renamed the channels XML file to match the Defaults name then wrote the channels back to the mpvi3 device. It looked like it was working at a glance but obviously not.
That first log was using my laptop however the laptop has a crappy battery and will likely last 2 mins on the road. I'll give it a go anyway as it seems like the laptop logging is providing what is needed ?
Also not entirely sure how to get the injector part number but I posted the engine specs above in this thread. Its a 427.
From: https://factoryfiveengines.com/gm-427-c-i-ls/ it says 42 lb injectors
Have you looked for a part number on the injectors?
still looking. I'm going to ask Blueprint too to make sure. This engine was ordered in 2020 and shipped early 2021, still in the chaos of covid aftermath so who knows what parts they used.
Tangent: Not a good advertisement for stand alone data logging. Is that really how bad it is? I've always wanted to upgrade.
Its not the easiest to setup. I'll take a look at it again one day but I'm just going to use the laptop for the next logs.
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