Intake cleaning spray thread

[Greg Roles]

Hey all,

As I get a LOT of questions related to PCV and catch cans, thought I'd start a thread to hear peoples experiences and techniques of using intake cleaning sprays. I'm aware of a few different brands, but have recently been recommending the "Subaru upper engine cleaner" SA459, an aerosol spray. This needs to be added after the air cleaner element, and to be safe, alongside / after the MAF as they can be sensitive. I need to find out if this stuff is MAF safe. That said it does take a bit to kill a MAF, but what I am trying to do here is amass all the information, as I'm no absolute expert on this stuff.

From a Subaru website:

Half a can is sprayed it then wait 10 minutes. Then the vehicle is started & whilst idling (juggling the throttle cables) the remainder of the can is sprayed into the inlet & the engine is turned off. Wait another 10 minutes, then restart the engine & rev it to 4000+ revs till the smoke from the exhaust clears. ( I'd suggest on a warm engine!! )


It will smoke a LOT, and make sure your exhaust is facing somewhere it doesn't matter, as a lot of black crud will end up on the ground behind the car, could really spoil a nice garage! In a normal petrol car, the car will struggle to run on it, will need a bit of throttle to clear it all. A diesel is ENTIRELY different, and this stuff will act as a fuel and make it rev right out. In a diesel you need to slowly add it whilst idling, and I mean slowly, as easch squirt is like opening the throttle, or best idea is to make up an intake restrictor plate, so that the intake is reduced down to a hole the size of a 5-10cent piece, thus preventing max revs as the spray is added. I also found a picture of the LiquidMoly product used by Ramspeed on the diesels - I am researching diesel specific products at the moment, but all the usual Subaru, Seafoam etc etc are not really suitable, as the diesles will throttle up on them.




In no whay whatsoever would I recommend using this or any oil removing spray on a DPF equipped diesel, as it will all end up in your DPF, and oil ash cannot be regenerated or burnt off. You DPF types need to be running a Provent from new, and consider methods to reduce the EGR introduced. For the time being that's all you can do.

Be interested to hear and see what people have done, and especially pictures of where you added the spray along the intake on the various models. Also love to hear of other brands such as Wynns who have similar products.