SIDI carbon cleaning thoughts??

[Skylarking]

Wouldn’t hurt to spray some upper engine cleaner in the intake with the engine running

Well it can hurt if care isn’t taken and too much liquid enters the engine.

It can cause hydro-lock as cautioned within the GM TSB I linked above

 

[RevNev]

I've used this (below) a few times on direct injection BMW's, with carbon sticking valves causing a cold start misfire and worked well. I've given a couple of LFX engines a dose, not to correct an issue but as a request by car owners concerned about carbon deposits on inlet valves.

 

[greenacc]

I've used this (below) a few times on direct injection BMW's, with carbon sticking valves causing a cold start misfire and worked well. I've given a couple of LFX engines a dose, not to correct an issue but as a request by car owners concerned about carbon deposits on inlet valves.

View attachment 257087

Where do you spray it on an lfx if the plastic intake pipe is in place?

 

[Commo64]

It's hard to say if that is how badly Holden built the 3 litre engine or if there's an issue that needs sorting.

Direct Injection engines are notorious for carbon buildup, irrespective of the brand... I wouldn't do anything if your car is running fine and it's been maintained well throughout its life...

 

[greenacc]

Direct Injection engines are notorious for carbon buildup, irrespective of the brand... I wouldn't do anything if your car is running fine and it's been maintained well throughout its life...

That's the thing.. does normal maintenance prevent carbon buildup? I don't think it does. I think the valves on these engines just slowly carbon up as you drive so it's only a matter of time before it needs a carbon clean.
But if it was a common issue there would be lots of late VEs and early VFs limping around with blocked up valves. And Im not seeing that...

 

[RevNev]

Where do you spray it on an lfx if the plastic intake pipe is in place?

The can has a long tube, and I sprayed it in the breather hose fitting on the LHS of the plastic intake pipe whilst someone on the accelerator revved the engine around 3000rpm. The engine runs rough whilst ingesting the contents of the can and takes some throttle opening to keep the engine running, good airspeed to suck it in. Smoke bellows out of the exhaust during the process.

 

[Commo64]

That's the thing.. does normal maintenance prevent carbon buildup? I don't think it does. I think the valves on these engines just slowly carbon up as you drive so it's only a matter of time before it needs a carbon clean.
But if it was a common issue there would be lots of late VEs and early VFs limping around with blocked up valves. And Im not seeing that...

Normal maintenance doesn't completely get rid of this issue but it certainly helps reduce the severity... Carbon buildup on these engines isn't as big of an issue as let's say VW Direct Injection engines, which are notorious for carbon build-up... My advice is to not get paranoid about this and only take action if there is actually carbon buildup, and the car isn't running right...

 

[Anthony .]

Don’t they use walnut shells to clear the carbon? Also, I’d say somewhat regularly giving the car a thrash at higher rpm (only when at operating temp) may help prevent buildup

 

[Immortality]

It's not so much of a problem because the bad PCV valve design keeps the gunk in the crank case

 

[Skylarking]

Don’t they use walnut shells to clear the carbon? Also, I’d say somewhat regularly giving the car a thrash at higher rpm (only when at operating temp) may help prevent buildup

I’m sure each manufacturer has their cost effective engineering solution to the poor design that causes such carbon build up.

So have a look at the Honda TSB I liked too and compare it to the GM TSB I linked to

PS: and manufacturers want you to use their own products so even if an abrasive is ground up walnuts with a specific particle size, they’d call it something like abrasive 10452983 and make various claims that it’s the only abrasive they recommend…

PPS: and whether abrasive blasting is needed depends on how bad the carbon build up is (which is why Subaru recommend carbon flush fluid at specific intervals).