So if you own or have done any reading on the TDV6 engine, be that the 2.7 or 3L that are found in the likes of the XF and S type Jaguar, in the Land Rover Discovery 3 or 4 and in most Range Rover models, you will know that a reasonably common issue is the EGR (exhaust gas recycler) valves.
These two valves which reside on each side of the engine, are tasked with allowing exhaust gases to be recirculated back through the induction and combustion chamber for the purpose of emissions control.
Now these valves are prone to failure but this post isn't about them, its about a byproduct of their use in the engine.
So what happens in the induction system??
The emissions enter the induction system just after the throttle body and mix with the intake air and a quantity of oil from the PCV (a byproduct from normal engine use).
This is where the problems start. When the oil and emission mix, they stick to the walls of the induction system and residual engine heat bakes it on. So over time, layer after layer of this carbon/oil mix builds up in the induction system, until there are significant deposits throughout the induction, from throttle body to the back of the valves.
So why is this a problem??
Well there are a lot of problems associated with these deposits. One we see often, is a blocked map sensor on the throttle body. Another issues include; a decrease in performance over time due to intake flow restrictions; EGR faults due to severely blocked EGR pipes; rough running engines and uneven idle.
To fix it?
There are a lot of products on the market for induction cleaning such as; Sea Foam, Liquid Molly, BG induction cleaner, Nulon etc. Some products I'm sure are very good, however they are really only useful when used throughout the vehicles service life. When a vehicle has significant deposits of carbon and sludge build up, there is only so much these products can do. Unfortunately the best fix is dis-assembly and manual cleaning. This can be expensive but is worth it as it will increase the performance and reliability of the engine, as well as extend its life.
At Pickards we manually clean all the induction parts with solvents and use a walnut shell blaster for cleaning the ports of the heads and the backs of the valves. We find that this is by far the most successful way of cleaning the ports (see here for an example on a bmw
If you own a newer vehicle or have had a full induction clean done on your vehicle the good thing is there is an easy way to keep the induction clean. This involves having regular induction cleans when having your vehicle serviced. I generally do it every 20,000 to 30,000 km. At this interval the induction sludge and carbon build up can be removed by a good quality induction cleaner as it hasn't had sufficient time to harden and collect.
For the ongoing cleaning of the induction during servicing we use a product, Prostream 1000, that is run through the entire induction system including the turbos and ERG valves. We have had a lot of success with this product.
Should you have any queries about the induction clogging issues or induction cleaning please contact me at www.pickardsautomotive.com.au or at (03) 9428 9655.