The tricks of engine tuning

Tempted as you may be to feed your power hunger with engine mods, make sure you only deal with a real expert.

Tempted as you may be to feed your power hunger with engine mods, make sure you only deal with a real expert.

Published Dec 30, 2010

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The electronics age has brought many benefits, such as reduced exhaust emissions, increased engine efficiency and even the capacity for tailor-made performance characteristics.

Tailor-made performance, what does that mean? Well, the electronic control unit (ECU) is a mass of electronic components, including a main processor which contains engine operating data and is in fact a "map" allowing a check on all ECU inputs.

The tailoring bit is left to engineers who determine what sort of behaviour is required from an engine, but most of the time the prime consideration is fuel efficiency rather than high performance.

Naturally, engine tuners have seen the gap here and realised that by re-chipping certain types of engine power and torque characteristics may be changed.

A "chip" is a piece of silicon that acts as the ECU's memory and, while early chips had to be physically removed from the ECU, it is now possible to re-program many of them via the diagnostic socket.

Many ECU faults are due to no more than the foolish location in which manufacturers place them. Any place that allows the site to fill up with water, whether it comes from the road or the screen, is bad news.

The drain holes inevitably become blocked with debris and flood the ECU with disastrous results. Check the location and keep those holes clear.

The claims for re-programming may at times be a little exaggerated and it must be accepted that power increases for normally-aspirated engines will be far less than for turbo-equipped engines.

The greatest increases will be achieved on turbodiesels.

Re-chipping will be expensive and it is important to get a full quote before signing up for the job. Also, where possible - even if it means visiting various tuners - get a drive in a car on which the work has been done to see if the performance justifies the expense.

Probably the owner of a late turbodiesel will be able to justify re-chipping, but shop around and refuse to be hurried before laying out any cash.

Many of the power gain claims are ridiculous and the gains may in fact be minimal.

Anyway it would be wise to talk to your insurance company before getting the work done. Some companies have an intense aversion to modified cars.

Lastly, a few cautionary words need to be said. Do not fiddle with electronics unless you really know what you are doing.

Unplugging the ECU may cause problems on some cars, as can jump-starting or even disconnecting the battery.

Voltage fluctuations can be death to an ECU so if you intend to use your trusty multimeter, be certain that it is set correctly.

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