Engine Carbon Clean - Any Experience ?

[Red 4]

Not sure whether to post here or in Engines and Drivetrain but looking for the general consensus.

Anyone had it done and noticed any difference/ benefits ? I'm looking at the hydrogen treatment (gas into the throttle body/ intake). Direct Injection petrol engine currently on 40k miles.

Local garage only charge £25. Seems rude not to.

[NMNeil]

This real world test would indicate it may be best to keep the 25 quid in your pocket
https://www.youtube.com/watch?v=Ro8IFUYryPg

[Red 4]

Hmm. OK, thanks for posting the video.

The pics showed that there wasn't much carbon removed from the valves but the car ran better with a microscopic gain in power.

That's what I'm looking for TBH. It's my wife's car, I don't drive it much but it has a slightly rough idle which my tinkering has not solved. I'll probably give it a whirl. It can't hurt I suppose.

Thanks again for posting the link. Much appreciated.

[colin_p]

Far better, at least once a week, to utterly thrash the tits out of it for a few minutes.

[NMNeil]

Red 4 said:

Hmm. OK, thanks for posting the video.

The pics showed that there wasn't much carbon removed from the valves but the car ran better with a microscopic gain in power.

That's what I'm looking for TBH. It's my wife's car, I don't drive it much but it has a slightly rough idle which my tinkering has not solved. I'll probably give it a whirl. It can't hurt I suppose.

Thanks again for posting the link. Much appreciated.

You could always try the old steam clean method.
https://www.youtube.com/watch?v=0pPmSLJXV4g

[GreenV8S]

Red 4 said:

Direct Injection petrol engine currently on 40k miles.

If there's nothing else wrong, you shouldn't expect it to be coked up at that age. And if there is, decoking won't cure the problem.

I suspect you'd have more luck checking whether the ECU is detecting any misfires and whether the adaptive fuelling changes are reasonably small.

[Pastie Bloater]

What car/exact engine is it?

[randomeddy]

VW/audi etc FSi engines are bad for it because of the design and position of the injectors.

Marque specialists do walnut blasting to clean it all.

[Red 4]

GreenV8S said:

Red 4 said:

Direct Injection petrol engine currently on 40k miles.

If there's nothing else wrong, you shouldn't expect it to be coked up at that age. And if there is, decoking won't cure the problem.

I suspect you'd have more luck checking whether the ECU is detecting any misfires and whether the adaptive fuelling changes are reasonably small.

Pastie Bloater - it's a Mazda 3 2.0 Sport DISI. 60 plate. Owned from new and the car has done lots of short trips ! It does get taken for a good blast once in a while but as you can see the mileage is very low for the age.

It's been such a good car - precisely zero has gone wrong with it - that I'm loathe to get rid and just run it until it dies. My missus has no interest in cars but she does love it.

No codes showing, just a (slightly) shaky idle. Maintained to within an inch of its life. Very sooty exhaust though !

[GreenV8S]

You could use an endoscope to see how much carbon there is in the chamber and then decide whether that's a problem. It may well be that the rough idle is something completely unrelated, and the ECU can probably tell you what that is if you have the right diagnostoic equipment. Or at least confirm it's in closed loop and the lambda readings are cycling reasonably quickly.

If you decide a decoke is needed, water injection is a great way to do that. The insides of my V8 were spotless despite it running very rich from time to time, and I put that down to the water injection.

[Chainsaw Rebuild]

What about filing it v power fuel on the grounds it has extra cleaning agent in it, and perhaps something like redex, and then taking it on a long journey? Worst case you have a day out somewhere.

[Tony1963]

I’m with the replies suggesting: at least one full tank of V-Power/BP Ultimate, a long drive (100 miles+), use high revs frequently.

If you think it still has a problem, it needs looking at properly with diagnostics, not snake oil.

[liner33]

Chainsaw Rebuild said:

What about filing it v power fuel on the grounds it has extra cleaning agent in it, and perhaps something like redex, and then taking it on a long journey? Worst case you have a day out somewhere.

Thats what I would do . Fill up with V power and go a spend it on the motorway at a nice cruise , roads are quiet and its a not a bad way to spend and evening and will do the car wonders

[320d is all you need]

Red 4 said:

Not sure whether to post here or in Engines and Drivetrain but looking for the general consensus.

Anyone had it done and noticed any difference/ benefits ? I'm looking at the hydrogen treatment (gas into the throttle body/ intake). Direct Injection petrol engine currently on 40k miles.

Local garage only charge £25. Seems rude not to.

Waste of money

Literally a waste of money.

[320d is all you need]

liner33 said:

Chainsaw Rebuild said:

What about filing it v power fuel on the grounds it has extra cleaning agent in it, and perhaps something like redex, and then taking it on a long journey? Worst case you have a day out somewhere.

Thats what I would do . Fill up with V power and go a spend it on the motorway at a nice cruise , roads are quiet and its a not a bad way to spend and evening and will do the car wonders

The reason this is a bit non sensible is because the whole idea is to remove carbon deposits which cause rough running and other problems

ON direct injection engines this extra "treatment" in the fuel only helps injectors, generally as cars have fuel filters this is never an issue
be cheaper to just run an additive from halfords (redex or similar)

- the reason for vpower or momentum would be the octane increases which do help and you need to use these continually

Back to the subject of removing carbon deposits which cause rough running etc these are on the back of the intake valve which is not touched by the fuel , and no amount of vaporised chemical sprayed into the intake will help, it would need inlet removing and intake valve cleaning via walnut blasting or other manual cleaning

[liner33]

320d is all you need said:

The reason this is a bit non sensible is because the whole idea is to remove carbon deposits which cause rough running and other problems

ON direct injection engines this extra "treatment" in the fuel only helps injectors, generally as cars have fuel filters this is never an issue
be cheaper to just run an additive from halfords (redex or similar)

- the reason for vpower or momentum would be the octane increases which do help and you need to use these continually

Back to the subject of removing carbon deposits which cause rough running etc these are on the back of the intake valve which is not touched by the fuel , and no amount of vaporised chemical sprayed into the intake will help, it would need inlet removing and intake valve cleaning via walnut blasting or other manual cleaning

Its only non sensible if you really believe a car with 40k has issues with carbon build up . The problem this car more than likely has is sticky injectors providing a poor spray pattern due to lack of use and short trips .

Some fuel with cleaning agents and a decent trip will most likely sort this.

[320d is all you need]

liner33 said:

Its only non sensible if you really believe a car with 40k has issues with carbon build up . The problem this car more than likely has is sticky injectors providing a poor spray pattern due to lack of use and short trips .

Some fuel with cleaning agents and a decent trip will most likely sort this.

Have you seen some intake valves on a DI engine at or around 40k?

It can and does happen unfortunately.

The problem with DI and overly zealous / poorly designed PCV required by modern emissions laws.

I hope we can both agree that these "terraclean" and similar products are a waste of money never the less

[Red 4]

Chainsaw Rebuild said:

What about filing it v power fuel on the grounds it has extra cleaning agent in it, and perhaps something like redex, and then taking it on a long journey? Worst case you have a day out somewhere.

Always run on Super (V Power or Tesco Momentum) and gets a shot of Redex if I fuel it (once in a blue moon).

It's had a couple of long trips recently (150+ miles at motorway speeds). It hasn't helped.

Recently had plugs, no codes. It just doesn't seem as happy as it usually is. It's fine under load (so have ruled out a coil on its way out) and drives great. It's just a bit grumpy at idle.

Thanks all. Advice is appreciated, as always.

[Red 4]

liner33 said:

Its only non sensible if you really believe a car with 40k has issues with carbon build up . The problem this car more than likely has is sticky injectors providing a poor spray pattern due to lack of use and short trips .

Some fuel with cleaning agents and a decent trip will most likely sort this.

EGR valves can be an issue on these cars with less than 40k. That's still a carbon build up issue. I don't think the short trips help due to the lack of heat to burn deposits.

I'll whip the EGR off and take a look.

[Nickp82]

I had a Mazda 6 Sky-activ diesel with carbon build up issues (infact I have had a couple).
A £25 carbon clean won’t do much (ime), Mazda dealers are equipped with proper gear to deal with it (involving walnut shells) and Mazda UK are actually quite forthcoming in offering goodwill to cars that have been serviced correctly as it is a known issue.
The cars I had were five or six years old so newer than yours and of course a different engine but given you have had it from new, it could be worth a quick call to a dealer to see if any goodwill might be available.