Tune Report: a second look at your LS tune
Send us your HP Tuners file. We compare every key setting with similar builds and tunes we've reviewed, read your datalogs, and tell you in plain English what to fix first, what's worth a look and what's already in line.
Launch offer The full Tune Report: $19 free while we launch.
You sign in with your email (no password), upload your file and tell us about the build. Report within 24 hours, usually the same day.
What you get
Fix first, worth a look, in line
Your report opens with what to do next and the top three things to look at, in the order to do them. Then every finding gets its own card.
Compared with similar builds
Idle airflow and timing, cracker and follower, power enrichment, full-throttle timing, hot-air timing pullback, rev limit and more, each next to similar builds and tunes we've reviewed.
What it does, how it feels
For every setting: what it does, why it matters, and how the car can feel when it's off. Then how to change it yourself and how to check the result.
Datalog analysis
Warm-up, idle against its target, fuel trims by rpm and load for each bank, knock retard, full-throttle runs and, with a wideband, commanded against measured fuel.
First we check that the file matches the car: engine size, fuel, injectors, MAP sensor, MAF or speed density, manual or automatic. A wrong fact up front throws off everything after it, so that comes first. Behind every comparison: 6.2 million tune values from real LS tunes, read table by table.
Who it's for
- Cam swaps, from a mild truck cam to a big lope, where idle, timing and fuel all have to follow the cam.
- LS swaps on a factory GM computer, into anything.
- Naturally aspirated or boosted. Boosted cars finish on a dyno with a tuner there; the report helps you get there with a clean file.
- Someone else tuned it and you want a second set of eyes before you go further, or you're tuning it yourself and want to know what to look at next.
- HP Tuners users with a .hpt file. PCM Hammer .bin files are next.
How it works
- Upload. Your .hpt file and, if you have them, up to three logs. Tell us about the build; skip anything you don't know and we'll read it from the file.
- We read and compare. Every key table, side by side with similar builds and tunes we've reviewed, plus your logs. A person on our team checks every report before it goes out.
- Your report, within 24 hours, usually the same day, on your order page. We email you when it's ready.
- Optional: let us do it. Start-up File $79 or Full Custom $199. Then finish on a dyno.
What a report looks like
Sample. A made-up build, written for this page. It isn't anyone's real car or file.
LSSwapBible · Tune Report
Your C10: what to do next
Your file matches the engine you entered. The first thing to look at is idle timing: 15° in your file, where similar builds and tunes we've reviewed sit at 20–26°.
1972 C10 · 5.3 L
220/224 cam on a 113 LSA · truck intake · 4L60E
Pump gas · MAF · Naturally aspirated
- Idle timing Fix first
- Fuel trims at light cruise, from your log Fix first
- Hot-air timing pullback: where it starts Worth a look
Fix first
Idle timing
What it does: how early the spark fires at idle. The computer also moves it up and down to steady the idle.
How it can feel when it's low: a lazy, rough idle that runs hot and needs extra air to hold rpm.
Do it yourself: raise the in-gear and neutral idle spark a couple of degrees at a time, log after each change, and stop when idle steadies.
How to check: log idle spark and idle rpm together, warm, in gear and in neutral.
Or let us do it: Start-up File $79 · Full Custom $199
Finish the tune on a dyno.
Your report has a card like this for every setting to fix first or worth a look, then your log (fuel trims by rpm and load, knock, idle against its target, full-throttle runs) and the rest of your file grouped by what you feel.
What to upload
Your tune file (.hpt)
The file that's in the car now, saved from VCM Editor. Up to 8 MB. Not sure it's the current one? Read the car again and save a fresh copy.
VCM Scanner logs
Up to three .hpl or .csv files, 8 MB each. A wideband in the log helps the most. A warm idle of a few minutes, in gear and in neutral, plus normal driving and steady cruise, covers most of the report.
Don't make full-throttle runs just for us. If you already log full throttle on a dyno or a track with a wideband, send that log.
Recommended scanner channels
- Engine RPM: nothing can be placed without it
- Desired idle RPM: how well idle holds its target
- Engine coolant temp: warm-up vs warm running
- Intake air temp: heat soak and hot-air timing pullback
- MAP and barometric pressure: engine load, full-throttle check, speed-density fuel cells
- Throttle position (and pedal on drive-by-wire): finds idle, cruise and full throttle
- Vehicle speed: idle at a stop vs coasting
- MAF airflow (g/s) and MAF frequency: the MAF fuel cells, if you run a MAF
- Short and long term fuel trims, both banks: how far off the fuel is
- Knock retard: whether the engine is pulling timing
- Spark advance: the timing actually used
- Commanded lambda or EQ ratio: what fuel the tune asks for
- Wideband AFR or lambda: the only way to see real full-throttle fuel
- Injector pulse width and duty cycle: how hard the injectors work
- Idle airflow / IAC: how the computer is holding idle
- Current gear: which idle and shift tables are in play
Channel names vary between scanner layouts; we match them by name and unit. Missing ones show up in your report as "add these next time".
Your file stays private
Your file is never shared, sold or published. We use an anonymized copy of every file we receive, with the VIN and anything that identifies you removed, to keep improving our comparisons for everyone. You can ask us to delete your files at any time. The VIN is optional, and we only ever show its last 6 characters. Full details in the terms.
Questions
Does it change my file?
No. A Tune Report only reads your file and tells you what we see. Your car stays exactly as it is until you decide to change something.
Do I need HP Tuners credits?
Not for the report. We read the .hpt you already have; you don't spend any credits on our side. If you later make changes, you write them with your own licensed interface, the same way you do now.
Is my tune safe?
We don't call any tune safe, and no report can. We show where your settings sit next to similar builds and tunes we've reviewed, what your logs show, and what we'd look at first. Every engine is different. Finish the tune on a dyno: that's where full-throttle fuel and timing get set with the engine actually under load.
Which files do you read?
HP Tuners .hpt files from LS-family GM engine computers, saved from VCM Editor. PCM Hammer .bin files are next on our list; until then, the turn-on tune sheet covers the same settings for free.
Do I need logs?
No, the file is the only thing you have to send. Logs make the report a lot better: with them we can check fuel trims, knock, idle and, with a wideband, full-throttle fueling.
Is it really free?
Yes. While we launch, the full report is free (normally $19). Orders placed during the offer stay free. Nothing to pay and no card needed.
How long does it take?
Within 24 hours of your order, usually the same day. We email you as soon as it's ready.
Who reads my file?
Our software reads every table, and a person on our team checks every report before it's released to you.
Can I use this on a street car?
Our reports and tune files are for off-road and competition vehicles, and for vehicles exempt from emissions rules where you live. We don't remove or disable emissions equipment on vehicles used on public roads. See the terms.
Get your free Tune Report
Upload your file and get a plain-English review within 24 hours. Normally $19, free while we launch.
Just getting it running? Start with the free turn-on tune sheet or the HP Tuners walkthrough.