Your Car, Your Responsibility
It's commonly known that getting your engine tuned is one of the best ways to gain extra power. But before a car even gets close to the dyno, any reputable tuner will always carry out a thorough inspection to make sure it's safe for them and your engine.
Tuning pushes engines harder than normal driving, and small issues can quickly turn into expensive problems. Aside from that, wheels spinning at over 100mph whilst stationary can get sketchy real quick if anything were to go wrong.
Prepping your car not only saves money and time, but it also ensures your tuner can focus on performance instead of fixing preventable faults.
Having worked at a tuning shop for several years, I’ll give you my first-hand experience and advice to help you be as prepared as possible to set your tuner up for great results.
Why Preparation Matters
Tuning shops expect your car to be in good health when it arrives. If it isn’t, you risk delays, extra labour charges, or a session cut short. More importantly, existing issues can get worse under load. A car burning oil, leaking coolant, or running on worn tyres could fail on the dyno. Taking time to prepare now means you’ll leave with more power and lot less headaches.
What Your Tuner Will Check
You should understand that tuners don’t perform a full mechanical inspection when doing their pre-tuning checks. That part is your responsibility or your mechanic’s. If you want a mechanical health check, that is something you should get completed beforehand, but you should check with your tuner to see what they offer. If there's ever a good time to do it, it is before modifying your car or taking it to the track.What your tuner will inspect is more focused on keeping the session safe and identifying the problems that we most often see with your specific engine type. This is when taking it to a specialist pays off. They will know exactly what to look for.
A good tuner will typically:
- Run a smoke test to spot vacuum or boost leaks that could ruin data or cut a session short.
- Inspect for common failure points they know well from experience with specific engines.
- Check the engine timing is within specification
- Listen for unusual noises under load, such as detonation, belt slip, or failing bearings.
- Look over the fuel system and ignition health to make sure the engine can deliver enough fuel and spark for the tune.
- Check logs or live data to confirm the ECU is behaving normally before changes are made.
These aren’t exhaustive checks, but they are vital. A tuner’s job is to focus on calibration, not to rebuild your car. If something major is uncovered, expect them to stop and advise you to repair it before continuing.
Fluids and Leaks
Start with the basics:
Engine oil
Make sure it’s at the correct level and fresh. If you’re close to your service interval, change it. It’s also worth asking your tuner which oil grade they recommend, as some engines perform better on different viscosities.
Transmission and differential fluids
Follow your maintenance schedule, change it if you’re near or overdue. Especially significant when there's a large increase in torque.
Coolant
Check the level and system condition. Poorly maintained cooling systems are one of the biggest causes of delays and leaks on dynos. Air pockets or leaks can cause overheating, especially when your engine is being pushed hard. Leaks or radiator hoses popping off cause significant delays.
Leaks
Fix oil, coolant, or fuel leaks before the session. Fresh fluids protect the engine when it’s pushed hard, and stopping leaks ahead of time saves you wasted dyno runs. If your car leaks fluids on the dyno, you either waste valuable time or risk being charged extra for the time it takes to clean and repair.
Spark Plugs and Filters
Think of this as a tune-up before the tune.
Spark plugs
Install a fresh set and ensure they’re the correct type and properly gapped. Worn plugs misfire under load. If you want to maximise performance, speak to your tuner about upgrades (running a cooler grade spark plug).
Air filter
Check it’s clean and flowing freely. A clogged filter limits power. Replace if it’s old or has a large build-up of contaminants. And if it's aftermarket, don’t assume the filters don’t need replacing.
Fuel filter
If it’s overdue, replace it. Numerous dyno sessions have been paused due to having to replace old and clogged fuel filters. It doesn’t matter what fuel pump you have; when more fuel pressure is requested, an old fuel filter will put a stop to that.
These are the simplest parts and are usually the most inexpensive to check or replace compared to the cost of wasted dyno time.
Belts, Hoses, and Loose Hardware
Weak belts and hoses are common failure points under high RPM. Inspect and replace anything that looks cracked, glazed, or brittle.
Secure all:
- Intake and intercooler pipes
- Vacuum lines
- Exhaust bolts and clamps
A loose pipe blowing off mid-run ends the session instantly. Tightening everything beforehand avoids wasted time and fees.
Check Engine Light
If your car shows a fault code, sort it before tuning, or postpone your booking. Misfires, sensor errors, or emissions faults can throw off data and prevent a safe calibration. The only exception is if your tuner already knows about a code linked to a removed part, but always confirm in advance.
Fuel Up Properly
Never arrive at a dyno with the fuel light on. It's common sense. A tuning session can use far more fuel than normal driving. Ensure your fuel tank is at least half-full of fresh, high-octane fuel and is the exact grade you want to be tuned for (for UK readers, 99 or E85). Running low on fuel risks pressure drops, inaccurate readings, and wasted dyno time.
Tyres and Safety
Unless your tuner uses a hub-dyno, your tyres make contact with the dyno rollers similarly to how they would on the road. If they’re bald, cracked, or unevenly worn, they could slip or even blow out. Check:
- Tread depth and condition
- Correct pressures
- No sidewall damage; bubbles, cuts or cracks
Safe tyres ensure accurate readings and protect both your car and the dyno equipment.
Drivetrain Checks
Power gains are useless if your drivetrain can’t handle them.
Clutch
A worn or slipping clutch won’t survive extra torque. Replace it if it's old, especially if it's already slipping.
Transmission
Fresh fluid is a smart precaution if you haven’t changed it in a while or have no record of it being replaced.
Differential and Axles
Listen for whining or clunks and address them first.
Brakes also matter. In most cases, they aren’t used much or at all during dyno runs, but they’re needed if something goes wrong, for street testing and general safety around the shop.
Suspension
Ride height
If your car is low to the ground or doesn’t have much of a gap between the wheels and the arches, I would strongly advise raising it. You may be turned away if your car won’t go on the dyno. Even if it's a chassis dyno at ground level, the rollers won’t be. You’ll often find dynos above ground level that simply use ramps to get the car on the rollers, which can often limit access.
Arms and Bushings
If you’re aware of any play in your bushings or are hearing any knocks or bangs, get them taken care of. Many tuners will utilise suspension components to strap the vehicle down on a chassis dyno to keep the car safe and stable. If there is any unnecessary movement or potential for failure, it could cause more problems than you’d think.
Final Checks
Before heading to the tuner:
- Ensure the battery and charging system are in good condition.
- Check all grounds and connections.
- Bring basic spares (belts, plugs, a coil) if you have them.
Any reputable tuner will perform a pre-tuning inspection, but arriving with a clean, fault-free car helps the session run smoothly and avoids any unnecessary fees. They will also love having you back!
The Payoff
After reading this, some of you might think it’s overkill and sounds like you need a full inspection before tuning. But the truth is, a lot of the items in this guide are things that should already be maintained for any vehicle, street legal or not.
If your engine tuner refuses to put your car on the dyno until repairs are completed, remember that it's not just your tuner's reputation on the line; it's a liability that engine tuners take on, and if something goes wrong, they usually get the blame.
Preparation takes effort, but it’s worth doing and will benefit you the most. A well-maintained car produces more reliable results, tunes without headaches, and avoids costly surprises. Your tuner will appreciate it too.
A healthy engine during tuning is imperative. Not just for the health of your car during tuning, but once you get it out onto real tarmac.
Arrive prepared, and you’ll leave with a car that’s not just more powerful, but more dependable, even when pushed hard.
Happy ripping!
