Is your car healthy enough for a remap? How to tell

A remap is not a repair. It asks the engine to work a little closer to its limits, so it assumes the engine is in good shape. How do you know that before you book? You don't need a garage for the first steps.

Signs that need attention

If you notice any of the following, the cause needs to be found first:

• Engine warning light on, or coming on and off.
• Loss of performance compared with the past, or the engine cutting power under hard acceleration (limp mode).
• Smoke. Black usually means too much fuel or too little air, blue means burning oil, and persistent white can mean coolant in the combustion chamber.
• Unstable idle, jerking, hesitation when accelerating.
• Oil or coolant consumption that you have to top up often.
• Whistling or hissing from the engine bay as boost builds.
• A slipping clutch: revs rise without a matching rise in speed.
• On diesels, DPF regenerations much more frequent than before.

Five checks you can do yourself

1. Service history. When were the oil, filters, spark plugs (on petrol) and cambelt or chain last done, where fitted? If you don't know, assume it needs a service.
2. Levels on a cold engine. Oil at the right level and not black like tar; coolant at the right level, with no oil in it.
3. Visual check. With a torch: oil around the turbo and intercooler pipes, split hoses, missing clips.
4. Cold start. Listen to the first few seconds. Knocking, rattling or a blue cloud from the exhaust is information.
5. Read the fault codes. An inexpensive OBD reader with a phone app is enough to see stored and pending codes. Don't clear them before you come in. A code that keeps coming back tells us a lot.

What a data log shows

If you have an app that logs data, a few values give a good picture. You don't have to analyse them; just send them to us:

• Requested and actual boost. If actual stays consistently below requested, there is a leak or a problem with turbo control.
• Fuel trims on petrol engines. Large positive values usually point to an air leak or a fuelling problem.
• Ignition corrections (knock) on petrol engines. Constant corrections in standard form are not a good sign.
• Rail pressure on diesels, requested and actual.
• Air mass (MAF) compared with what the engine should be drawing.

Don't do full-load tests on the road just to fill a log. That is a job for the dyno.

What we check

Before writing any calibration:

1. We read fault codes and live values from the ECU.
2. We do standard runs on the 4WD dyno with the car fully warm.
3. We log pressures, temperatures, ignition and fuel corrections at the same time.
4. We compare the result with what the engine should produce in standard form.

If everything is in place, we go ahead. If something is missing, we show you the data and decide together: repair first and remap afterwards, or not at all if it isn't worth it. It is better to hear "not yet" than to pay for a result that won't last.

Mileage is not the issue

A high-mileage engine that has been properly maintained is often a better base than a newer one that has been neglected. Condition matters, not the number on the odometer.

See what is available for your vehicle in the car finder or book a dyno check.