Cleaning intake valve service

BMW N54 Intake Valve Cleaning via Walnut Blasting

Our customers kept raving about how well their cars drove after our technicians completed the intake valve cleaning on their N54 powered cars..  (Found in the BMW 135i 335i 535i and 740i) We knew the carbon build up was causing poor fuel economy, rough running and power loss; We never expected the results we achieved with a before and after Dyno comparison.

The issue: Direct injection engines are designed to spray fuel directly into the cylinder rather than the older conventionally injected engine which would spray fuel into the intake port above the intake valves keeping them clean.

Direct injection was designed to increase fuel economy and performance. It has done a pretty good job at both, Unfortunately the intake valves no longer get cleaned by fuel flowing past them. Recycled blow by engine oil re-routed through the intake manifold heats up and forms carbon build up on the back side of the intake valves and in the intake ports, in turn blocking the correct amount of air from entering the cylinder.

The intake valves and ports now need to be cleaned manually to re-open the ports and get your horsepower back!

So this is where our adventure begins.  It was a warm Friday morning. A beautiful space gray BMW 335i coupe 6 speed came into the shop for an intake cleaning.  The car had been properly maintained all of its life, regular oil changes etc. Our test subject had 112k miles on it. It had very few modifications making it a great candidate. The car had a free flow exhaust, dual cone open air intakes and a charge pipe. The carbon build up was average, we’ve seen much worse.

We began by strapping the car to our dynojet dyno and doing 5 consecutive pulls. The temperature was 87*F. The car made a respectable 294 rear wheel horsepower on its best pull.

Next we began the intake valve cleaning process.  We remove the intake. Cover up/seal the intake charge tube, both air intake tubes, and any other openings. Then we determine what valves are open and which are closed. We cover the ports that the valves are open. We take before pictures, then load up our equipment.  We have a BMW specific attachment that fits precisely into the intake port on one end and the other hooks to a vacuum. The attachment has a small hole in it to inject the crushed walnuts. Next, we fire up the vacuum and start spraying walnuts into the intake ports in short blasts followed by compressed air. We remove the assembly and check how it looks. Most of the time, we have to carefully go into the port with sharp metal pics and scrap off some of the stubborn build up, then repeat the procedure until our desired results are achieved. We use very strong chemicals to give the ports one good final clean. Finally, we check to make sure the ports are clean of carbon and leftover walnuts.  This process is repeated on the remaining closed cylinders, then we turn the engine over to close the remaining valves and finish the cleaning process. Lastly, its time to take some after pictures! We re-install the intake, installing new gaskets & new vacuum lines to the vacuum pump and the diverter valves.  We start the car, double check our work and were done!

Now that we finished the procedure, we let the car warm up and strapped it back onto the dyno. The temperature is now at 91*F.  We did 5 more pulls.

As we were doing everything, we discussed what the rear wheel horsepower might be. The general consensus was an assumed 3-5 peak horsepower gain.

Well… We were wrong. Significantly wrong. The car now makes 308 rear wheel horsepower! a 13 hp gain!!  Gains were seen through the entire graph. The most significant gains were seen in the higher rpm range at 5500 rpm, with the gains greatly increasing until 6500 rpm where there was a whopping 39hp gain!!! At 6500 rpm before the cleaning, the car only made 255 hp. Now it makes 294 hp. We’re speechless!! The results literally gave me chills.  As you can see in the dyno graph, the power gains can make the difference of losing a race and walking away from your competition!

The hp gains are great! Imagine how much better the fuel economy gets (if you can stop yourself from utilizing your newly regained power). The cars always run much smoother and sound better.

EuroMpire recommends performing this service every 60k miles to keep your car’s power and fuel economy where it should be!


Contact us TODAY for more information, or to make an appointment!


Before and after Dyno results showing a 13 peak horsepower increase and a huge 39 rwhp increase at 6500 rpm!

intake valve dirty

Intake valves and ports before cleaning.

Cleaning intake valve service

Intake valves and ports after cleaning. So much room for activities!!

dirty from cleaning

We sifted out the walnuts vacuumed up after the procedure and recovered all the carbon (quarter for size comparison) All this was blocking the intake ports. Its enough to completely block one entire port!!

dyno after cleaning

Dyno graph showing the temperature difference! Ready to restore your vehicle’s performance? Contact Us to make an appointment!