The engine is the most crucial part when it comes to tuning, if the engine isn’t in good health the car will not run right. Things like compression testing a vehicle, if the compression is low the engine will not perform as strong as it should, This is something that can and will sometimes be carried out by SM Tuning before mapping to ensure the engine is in good health and running strong. The difference between good compression and low compression is a big jump when it comes to power figures. We’ve seen some engines lose as much as 50bhp when compression is around 100-120psi instead of the usual 140-180psi more commonly seen. Misfires are also something that tends to happen. SM Tuning carry some spare parts for some vehicles for the most common causes (Like plugs and coil packs). Generally it can be sorted on the day, but ideally it needs to be sorted before hand. Misfires are usually a sign of plug failure or coil pack problems, which is ultimately an easy fix which we can carry out before tuning. However fuel pumps, injectors, fuels lines etc can also be a factor to misfiring, which, if we were to try to repair on the day and within your allocated slot, just could not realistically happen. Service schedules should be up to date, along with cambelt’s etc. A worn cambelt will kill an engine if it fails during tuning. Sludge and carbon deposits can lead to oil feed lines becoming clogged up, starving important components such as turbos of vital fluids. An easy disaster to avoid with regular oil changes. Smoking is something that also needs to be addressed. Smoking is common on the Vauxhall’s due to the valve stem oils seals, but also can be for other reasons. Smoking can be blocked breathers, Turbo oil seals, Failed piston rings tired engine etc. If your vehicle is smoking, and is booking in for tuning, Please contact us, or let us know so we can address it before tuning. SM Tuning will generally refuse to map a car if it is smoking due to the various implications it could cause. (This is taken on an individual case, and each vehicle would be evaluated). Actuators on turbo’s are another crucial part to making sure the turbo runs the right amount of boost pressure required when tuning the vehicle. This is something that isn’t as easy to check unless you have access to testing equipment, if you are unsure it can be tested on the day of mapping. This in itself isn’t a major issue that would mean mapping couldnt take place (Depending on how bad the actuator is), its certainly worth noting though.
Not something that people would probably think is related to tuning, but it all plays its part. Tyres are the only thing that keeps you in contact with the road and should not be skimped on, or risked under any circumstances. Recently SM Tuning couldn’t put a car on the rolling road due to a vehicle having non road worthy tyres. This is something that needs to be sorted before tuning. If a bulging tyre did give way on the rolling road, the wheels are spinning at over 100MPH in some cases and this would cause some serious damage. If the tyres are not in road worthy condition, then the tuning will not be able to take place.
Relatively small on the scale of the above issues, boost leaks can cause all sorts of havoc. If you think you have a boost leak, or are concerned, then get a garage to do a smoke / leak test on your car to check for leaks. Vac leaks can also be identified using this process. Vac hoses play a huge part in making sure your engine runs good. Most engines now run a boosted fuel pressure regulator meaning that (for example) the static 3 Bar fuel pressure is added to the boost pressure which equates to your fuel pressure. If you run 1 bar boost, your fuel pressure at 1 bar boost would become 4 bar fuel pressure. If you have a vac leak, this may cause your fuel pressure to drop off and starve the engine of fuel. Vac leaks can usually be identified with a boost gauge. If you are worried though, get it checked.
Warning lights are usually the first part of the puzzle when something goes wrong. You might not always get an engine warning light on if something is wrong, but SM Tuning have had many cars over the years where people think the map will solve all the issues and fix the lights. This isn’t always the case. In situations where people have gone for a sports cat / Decat this can be solved during mapping if the engine management light is on for catalyst efficiency. Generally faults need to be rectified before tuning though. SM Tuning have tried to “gloss over” the issues and explain them in a way that we hope will help people in the future of tuning there cars. This doesn’t automatically mean if you have an issue it cannot be tuned, but the sooner you mention it to your tuner the sooner we can start to look at resolving it or looking at options to get it sorted and reschedule your tuning appointment. It makes life a lot simpler and saves a lot of time if a vehicle is fit for mapping before hand, then having to try resolve issues on the day and potentially refuse to tune it. In future if you have any issues and are booked in with SM Tuning, please let us know ASAP.