Recently, I've noticed my diesel makes more smoke. Is it tune related or is something wrong with my car?With the Summer season warming up, you're probably experiencing hotter temperatures where you live. You might also have noticed that your tuned diesel has started making more smoke than usual. Before you call your tuner or start throwing parts at your car to figure out what's wrong with it, let me explain why this is, in most cases, normal. Or at least, why you should expect to see some smoke when it's hotter. The basic principals of diesel combustion is to compress air and fuel (diesel) together until it goes boom. To make power, there is a careful balance of mixing the right amount of air and fuel together (among other things). Since temperatures can change the density of air, it's important to understand how that factors into the combustion of diesel.Air Density MattersYour diesel engine uses air and fuel to combust. When the air is cold, it's more dense and can combust more of the fuel that it's given. When the temperatures start to heat up, the air density lowers, effectively giving you less air to combust with the same amount of fuel. This can lead to more unburnt fuel exiting the combustion chamber and creating an increase in soot leaving the tailpipe. A tuned diesel engine can be especially sensitive to this.Why didn't I notice this when the vehicle was stock?A Stock ECU tune is much more conservative and keeps fuelling and boost within a lower range. This allows the factory cooling system to keep up with the extreme temperature differences and fluctuating IAT (Intake Air Temperatures) which means it will be less sensitive to air density changes. When you increase power, you are playing closer to the limits of the factory hardware. The factory emissions systems also help to filter a lot of the soot that comes through. When dealing with performance increases, there are some compromises that must be made to achieve those gains. And if you are still utilizing the stock cooling system, you will reach it's limit sooner.How can I prevent it?There are several ways to remedy this. Generally, if you are experiencing higher ambient temperatures (and therefore also higher IAT's) you can try one, or all of these things.1.) You can switch to a lower output Stage tuneIn most cases our Stage 1 tunes will not suffer from drastic temperature changes. The stock cooling system may still not be able to keep up with extreme temperatures, but for most regions this will solve most of the problem by lowering the boost and fuel request enough that the factory intercoolers are able to cool the charge air enough to burn efficiently in the combustion chamber.2.) Upgrade your cooling systemIf you're dead set on keeping the power you have and don't want to compromise on your power output, you can upgrade your cooling system. A larger intercooler with more surface area can usually be enough of an upgrade to cool the intake temperatures down to a more suitable range to keep the air density lower enough to make a clean (full) burn in the combustion chamber. In some cases, this may even increase power output ;) Some customers even opt for extreme cooling upgrades such as installing a water meth kit. While effective at keeping IAT's low, these can often be expensive and finicky to setup properly, and sometimes requires custom tuning.4.) Maintenance and RepairIn some cases, hardware upgrades and de-tuning aren't necessary. Depending on your vehicles mechanical condition, you could reduce smoke output by cleaning out your factory intercoolers. Over time, intercoolers can get clogged (dirt, bent intercooler fins, reduced airflow, etc) - A good starting point would be checking your intercooler and making sure it is in good operating condition. Double check your air filter. If you have a dirty or clogged up air filter, that could be reducing the amount of air coming into your engine effectively creating less air density as well.3.) Custom TuningAs a last ditch effort, if you live in an extremely hot climate you may need to get in touch with us about having your ECU custom tuned for your specific needs. However, it's important to note that this doesn't necessarily mean you'll get more horsepower either. If you're unsure if custom tuning would be right for you, you can always open a ticket and our Calibrators can assess your specific setup to determine if it's right for you. For small tweaks, we may be able to do a tune revision based on your data logs. A logging tool like VCDS or Vehical is necessary to provide data logs and/or request custom tuning.