Lexus IS250 and GS300 intake valve carbon fix/cleaning with walnut blasting

After a lot of research, CARspec performed our first walnut shell blasting of an IS250’s intake valve to remove carbon buildup that causes misfires and a rough running engine.  You can read more about the rough running issue in this blog.  A common repair on direct injection BMW and Audi engines, very few (if any) repair shops offer this service on Lexus direct injection engines.  This 2006 IS250 already had its pistons and rings replaced under the enhanced warranty ~30k miles prior to this cleaning.  Here’s what the valves look like before the process (upper and lower intake manifolds have been removed):

IS250 intake valve

While the warranty enhancement repairs the misfiring symptoms with new pistons, rings and valve cleaning, it doesn’t address the base issue of carbon buildup on the intake valves.  The goal of walnut blasting was to proactively remove the deposits.  The results were surprisingly good:

IS250 Valve before and after

On the left is a cleaned valve, the right uncleaned.  There were some pretty big chunks that came out:

IS250 Valve Chunks

The process requires extreme care be taken in preventing walnut media from finding its way into the cylinders.  Lots of tape was used, moving from port to port individually, protecting the rest of the engine with fender covers:

Protecting the Engine

The process takes two technicians roughly 3 hours to complete.  The owner had this to say:

Better more immediate throttle response and smoother idle. I’d highly recommend this service. Even with only 33k miles worth of carbon buildup, it’s likely to be night and day difference for someone who never has had a cleaning done and is outside of the Lexus powertrain warranty.

This may prove to be a suitable repair attempt (combined with top engine clean) to a misfiring IS250 out of the extended warranty program or as routine maintenance.

As Eden Prairie and Chanhassen’s independent Toyota and Lexus repair specialist, we hope this helps an IS250 or GS300 owner out of the warranty enhancement that has a rough running engine.  If you’d like to read about other unconventional repairs we’ve done, check out this blog about swapping an Land Cruiser suspension into an LX470 or this sway bar repair on an older Camry.

Note this process isn’t needed on engine with D4S direct AND port injection engines like the 2GR-FSE in the IS350 or GS350, only the 4GR-FSE and 3GR-FSE of the IS250 and 2006 GS300, respectively.