Rick's Free Auto Repair Advice

What is a performance chip

Performance chip and Performance tune

A performance chip is an old reference that refers back to the days when auto computer software was contained in a read only memory “chip” that was inserted into the car’s powertrain control module at the factory. Later, if the car maker updated the software, the dealer would remove the old chip and install a new one.

Late model cars don’t have removable chips. They can be updated with new software through the diagnostic link connector and a special “pass through” device and a laptop computer.

When companies sell a “performance chip” they’re actually selling modified software to bypass the car makers’ operating restrictions to “gain more power” from the same engine.

How does a performance chip get more power from the same engine?

First, you can get more power from an engine by advancing ignition timing. So the spark plug ignites the air/fuel mixture earlier than the car maker specified. Does it work? Well, yes, but not without risk. First, igniting the air/fuel mixture earlier can cause engine knock. The car maker’s software would detect that knock and retard timing to eliminate it. But performance programming sometimes ignores signals from the knock sensor, so over time, that knock can cause engine damage.

Next, igniting the air/fuel mixture earlier will cause your vehicle to pollute more. If you live in an area with emissions testing, chances are you’ll fail. Altering the ignition timing in a way that causes the engine to pollute more is ILLEGAL.

Does a performance chip work?

Well, yes. They boost power slightly, but nowhere near the advertised amount. That’s because there’s really no free lunch. If they boost power in the wide open throttle range, they’ll cause a LOSS of power at part throttle. That will usually be NOTICEABLE as you tool around town. If you’re taking this vehicle on the track, fine. But if it’s your daily driver, you won’t be happy.

Are there Downsides to a performance chip

Yes, plenty. Have a look:

Lower gas mileage

Here’s a quote from someone who installed a performance tune and is going back to the stock software: “Peter Cheuk of Daly City, Calif., is a computer technician, so installing his Upsolute chip wasn’t a big deal. And he gained 18 horsepower and 70 foot pounds of torque in his modestly powered turbodiesel 1998 Volkswagen Jetta TDI. Still, he plans to return to the stock chip. He said that the problem was that, because he now drives faster, he lost 10 miles a gallon in fuel economy and, even worse, is now trailed by clouds of black smoke. ”But if it wasn’t for the smoke, I’d be happy with it,” he said.” —New York Times

Think about that, losing 10 miles per gallon!

You’ll most likely have to switch to premium gas

Premium gas helps prevent detonation and knock. Are you ready to spend .35 more per gallon AND get lower MPG at the same time?

Premature engine and transmission damage

Aside from causing you to fail emissions testing, some performance chips can actually damage your engine or transmission. As I said above, advancing ignition timing and ignoring knock sensor signals can cause significant engine damage.

If your performance chip tune is designed to give you more power and torque from a stop, that places more stress on an automatic transmission. The clutch pack pressures are designed for a certain RPM and torque. To handle the additional torque from a performance tune, the software writers alter the transmission software to apply higher pressures to the clutch packs.

To give you some perspective on this, let’s look at how a car maker would approach this same topic. Let’s say one transmission basic design can be used with many different engines. If it’s installed in a vehicle with a small engine with lower torque, it will contain a clutch pack with a set number of clutch discs and steels, a specified spacer, and a certain sized clutch pack piston seal. To make the same transmission work with a larger engine or with a vehicle that’s ordered with a towing package, the clutch packs will contain MORE clutch discs and steels, different spacer and a different seal. The transmission may be equipped with a different pump to achieve higher pressure. The engineers do that to eliminate clutch disc slip.

If you boost pressure on a clutch pack that isn’t designed to handle extra torque, you’ll get clutch disc slip. In other words, you burn up the clutch discs.

©, 2018 Rick Muscoplat

Posted on by Rick Muscoplat


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