Having been a member of various car forums and been asked whether these 'tuning chips' work a bazillion times by other members, and after seeing how many are being listed on Ebay, i thought it was time to set the record straight on what they are, and the harm they can do to your engine. Firstly, they neither chip or tune your engine - only a proper ECU chip, mapped to suit your car with the correct fuelling/air ratios can tune it (superchip, seb etc) and these are usually 100+ pounds to buy and are a replacement EPROM for the board in your cars ecu. They're NOT a 10p resistor available from any branch of maplins or RS. So what does this resistor actually do? In a nutshell it cons your ecu by sending it false information about the temperature of the air going through the airflow meter or IAT sensor on your cars engine. It basically makes the ecu think the air is much colder than it actually is. The colder the air, the denser it becomes. Dense air (if my physics is right) means that you're getting more oxygen per cubic centimetre (CC) in the combustion chamber which makes the mixture of fuel and air burn hotter, making a bigger bang and creating more power. Its this information that is used by the ecu to adjust the amount of fuel needed for the conditions its sensing, and proper running of the engine. Right, thats the science bit out the way.
So whats the problem with the resistor 'chip' then?? Right.....with one of these resistors fitted, your cars ecu recieves the air temperature info via the resistor which, as said previously, is not an accurate reading of the air temperature going into the throttle body. Because of this, the ecu makes the fuel system of your vehicle deliver fuel at a higher rate than the engine needs. Yes you might feel a small improvement in power (although in some vehicles the opposite is true) but too much or too little fuel is pretty serious as it can lead to detonation, lumpy idle, bore wash, higher emissions, lower mpg and, in extreme cases, even wrecked pistons!! Anyone whose ever had their car in for repairs at a garage will know how costly in terms of inconvenience and money this can be, and dont expect much help from the seller, as the small print on the packaging will state that no liability will be taken for damage caused from use of the product :(
Please remember what your parents probably told you many times - if something seems too good to be true it most probably is!! There are no tuning mods that deliver 20+ BHP for a couple of quid.....if it was that simple to gain horsepower from an otherwise standard engine car manufacturers development costs would be a lot lower and everyone would own a racing team ;) Unfortunately there are also no shortage of unscrupulous people who are only too happy to relieve you of your hard earned money by promising the earth and delivering a nightmare so research your subject before you buy.....
If you're serious about tuning your engine the best advice i can give you is to go online and join a forum that covers your make and model. This way you can speak to people who have already done it. They will tell you what works and what doesn't, whats good value for money and whats a con, and you'll meet friendly, like minded people as an added bonus :)
Well thats my tuppence worth - hope reading this has been of some usefulness to you. Please remember to mark it as helpful if it has been :)
Buy smart, and remember........fire burns! :P