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IS220D Inlet Manifold Cleaning - Carbon Removal


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First off, I am not a mechanic so my terminology may annoy some of you!


I did this as i was getting a lack of power at about 2500revs mainly in higher gears. It has improved dramatically. Fuel efficiency seems to have improved but only slightly so I can't say for sure. 


For this guide, I refer to right and left as you stand at the front of the vehicle looking into the engine. I know this is not the norm so apologies if confusing. Front refers to the front of the car as standard.


Also, the elec. connectors are the biggest pain in the &%$£. Trying to squeeze the clip and pull at the same time is so difficult as they are usually well stuck in place being nine years old! Don’t give up!


Job time – 10 hours over two days (I didn’t have a guide so hopefully you will do it faster – it would take me about 6 hours if I did it again)


Set up tools, bench, laptop, etc. (1 hour)

Disassembly (5 hours)

Cleaning (2 hours)

Reassembly (2 hours)


Basic tools are required but just having a good socket set is very important. Not necessary to jack up vehicle but would help. I drove the front wheels up on 3inch blocks.


This is the order I did it in, you may want to do it a little differently. I include headings for the most part but in general this order worked well.


Here we go!...




Remove primary engine cover

Remove RH engine cover

Remove LH engine cover

Remove front engine cover

Remove under engine covers (x2)




Disconnect Battery terminals

Remove Battery horizontal support brace

Disconnect the electrical connection on the LH side of the Battery cover

Remove Battery cover

Remove Battery

Remove base cover of Battery

Remove Battery vertical support brace

Remove control module under Battery (x3 bolts – long one goes on RH side)

Disconnect 3 elec. connectors on control module

Remove bottom Battery case (x3 bolts)




Remove EGR pipe and gaskets

Disconnect EGR elec. connector

Remove EGR valve




Open radiator cap and drain ***** (have bucket ready to take ~5 litres)

Drain fluid

Remove air intake duct above radiator

Disconnect inlet and outlet pipes of radiator fluid reservoir tank

Remove reservoir tank




Disconnect fuse box wire harness clips (x2)

Disconnect common rail front end elec. connector

Disconnect common rail fuel supply hose

Disconnect common rail rear end elec. connector

Remove wire harness support bolts (x2)




Disconnect EGR valve rear end elec. connector

Remove five wire harness clips (red arrows)

Remove harness support (green arrow)

Remove sponge adjacent to EGR valve

Lexus 01.png




Remove bolts (x3) on water pipe (blue arrow) below EGR assembly

Remove clip at front end of pipe and slide hose off

Remove vacuum hose (small) from water pipe (underneath)

Remove elec. connector under vacuum hose & remove clip also (hard to see but you’ll know it has to be disconnected)

Push hose assembly out of the way – towards Battery area (no need to fully disconnect)

Lexus 02.png


Air Flow (Throttle) Assembly:-


Disconnect three elec. connectors on air flow unit

Remove bolt on air flow unit

Lexus 03.png


Common Rail:-


Remove common rail bolt (x2)

Remove common rail fuel lines

Protect (tissue) the common rail connectors & ports

Remove common rail and keep clean


Inlet Manifold:


Disconnect vacuum hose from inlet manifold

Remove inlet manifold upper stay bolt (it’s a vertical support that can be hard to see)

Remove air flow pipe to inlet manifold (1 clip also) (difficult to remove for me but keep twisting and pulling – there is a lip to overcome)

Loosen inlet manifold lower stay nut (very difficult to access – hard to even see. This was the most awkward part of the whole job. You should really disconnect for easier access but it would be impossible to get it back on – loosening and pushing it aside was fine for me) See diagram below.

Remove bolts (~x9) on intake manifold

Remove intake manifold

Lexus 04.png




Clean inlet manifold – I used a power hose, carburettor cleaner, screwdriver for scraping & kitchen paper.

Clean inlet ports – as above but I used a hoover continuously to prevent as much carbon as possible entering the valves/cylinders


Reinstall in reverse – much easier than disassembly!


Prime the fuel system. 


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For a non mechanic as you describe yourself this is excellent, your mechanical skills are obviously better than you think.

Thanks for taking the time and trouble to write all this up, I'm sure it will be of great help to other members.

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Very good guide :thumbsup:

Do you have any picture of the manifold or inlet after you took the manifold off?

This seems to be a more and more common problem as mileages increase.  Guides like this give me more confidence to have a go.  

Did you change the manifold gasket?

Mine has 120,000 miles (hit 120k this morning :smile:), so I think it might benefit from a clean.

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@Steve - it's only a small contribution that pales in significance when compared to the help I've gotten from this site! 

@Shahpor - I'll attach some pictures soon. They are not great though and I regret not taking better ones. I read somewhere about a Is220d owner removing pounds of carbon from the inlet. I'd say I got about half to maybe a full pound. I didn't change the gasket. It's metal (like the EGR ones) and looked in good shape so I didn't bother. 

One thing I should add is that there are torque specs for each nut and bolt obviously. I didn't torque anything. I went good hand tight on everything but a little softer on the common rail connections. It is very important that they sit right before finding the thread. I didn't have any issues though.

I think DIY jobs like these all come down to confidence and it does help to know someone else has tried it first!!! 

The only problem is that bottom bolt on the inlet manifold stay. Persevere though!


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  • 6 years later...

So, I tried this ...  Got a LOT of carbon out...  But as I didn't have a "shop" hoover, ended up just scraping off loads, getting it out using a screw/screwdriver/finger.

Put it all back together, have primed for a while...  Double checked electrical connectors, vacuum hoses etc, all seems fine.

But car won't start.  Just turns over.

About to get the computer connected (managed to get techstream working today) but if carbon has entered the block, how bad is that?

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