Outer Limits 4x4 Board

Has anyone got any ideas on what product can be used to remove carbon build up from the combustion chambers of a petrol engine? I've found the procedure below which seems pretty good to me, but what product will dissovle the carbon?

http://www.nissanperformancemag.com/dec ... ning.shtml

I tried Nulon Throttle Body Cleaner, but it's a mixture of acetone and methanol so it's going to evaporate from the cylinder very quickly through the open valves. Valvoline Syntron Injector cleaner and Caltex Techron 5000 don't evaporate, but wouldn't dissolve some carbon deposits I scrapped out my old exhaust manifold. The Nulon stuff had no effect either before it evaporated.

The engine in question is suffering badly from detonation/ pre ignition and has to be run with the timing retarded by 2 degrees from factory specs, plus use 98 octane fuel. It's an EFI engine with mechanical distributor, fuel injectors have been cleaned and flow tested, and the distributor swapped with a known good item with nil change. Sparkplugs are correct heat range. Fuel flow rate is fine but pressure hasn't been tested.

I noticed a thick build up of carbon in the exhaust ports when recently fitting extractors, hence the question.

Get some Nitrox and double the amount it says to put in. See if that helps

Old mate of mine once told me that water sprayed down the throttle body works. A small plastic spray bottle with water, with the engine going, air cleaner or hose removed, spray the mist down the throttle and run for a while. From what he told me, the water helps to crack the carbon off the surfaces and then gets blown out with the waste gases. If you've ever seen a motor with a blown head gasket, and the head off, you would notice the combustion chamber/piston/valves of the affected cylinders are clean as. This was an older motor though, (no fancy electrics or CC) so perhaps use this method at your own risk on a newer motor...

Decarboniser from CEM.

http://www.costeffective.com.au

Cheers
Daryl

Have you tried a good long hard drive? Get out on the highway and go flat out (100kmh+) for 2 to 3 hours on a hot day. I you haven't, you should try that first before pouring 'products' into the holes in your engine.

Have you tried a good long hard drive? Get out on the highway and go flat out (100kmh+) for 2 to 3 hours on a hot day. I you haven't, you should try that first before pouring 'products' into the holes in your engine.

This is a good idea murcod In the feroza do it in 4th gear too so it revs a little harder and really gets to hard operating temps.

mj wrote:

Have you tried a good long hard drive? Get out on the highway and go flat out (100kmh+) for 2 to 3 hours on a hot day. I you haven't, you should try that first before pouring 'products' into the holes in your engine.

This is a good idea murcod In the feroza do it in 4th gear too so it revs a little harder and really gets to hard operating temps.

With this, if you do have a carbon buildup, you may get run-on, as the carbon will act like a glow plug. Not a bad thing, but doing this will help to determine whether you do have a carbon problem or some thing else is causing problems.

Thanks for all the answers. I'll look into those products mentioned too.

I took it for a decent long drive yesterday (Adelaide northern suburbs down to Deep Creek Conservation Park near Cape Jervois - a couple of hundred kms) that included a lot of hilly stuff and doing 100km/h in fourth for a bit of it. The first part of the trip to the outskirts of Adelaide I had the Techron 5000 (supposedly good stuff) in the tank mixed with about 15 litres of fuel - the recommended mix rate is with 45 litres.

I then filled up with Mobil Synergy 8000 (98 octane) when empty and continued the trip there and back. On the way home my favourite hill for "testing" the detonation revealed no problems- so either the Techrom stuff has done something or the Mobil 98 octane is better than the BP Ultimate 98? Previously I'd tried the Mobil and it seemed worse.

That's still with the timing retarded though and running the high octane in an engine that is designed for normal ULP.

I'll see how it goes this week.

I had heard about the water cleaning too, and having suffered from a blown headgasket on another vehicle so can vouch for how clean that one blown cylinder was. The question is how long would you need to have the water going though the engine for it to clean it out? It could take a bit of time to have any effect?

When I fitted the extractors the build up of carbon in the exhaust ports was ~ 1-2mm thick so I can only imagine how bad the combustion chambers might be!?

How much carbon do you have on your plugs? Just a thin film of soot or a heavy crust?

Soot and crap will always buildup in the exhaust ports and is not always an indication of how dirty the cylinders may be - just look at a chimney flue for example.

Just be careful of excessive retarded timing, you can burn exhaust valves as the flame front of combustion is later in the cycle.

Back to the run-on, when you shut the motor down, does it sometimes run on after an extended highway run?

There's no run on when turning the ignition off- but it's EFI so once the ignition is off the injectors won't pulse anymore to provide fuel. The detonation/ pre ignition is worse on hot days and only up steep hills; I notice it mainly in second and third gear.

Factory spec for the timing is 3 +- 2 degrees and I'm running 1 degree, so it's just inside that.

I haven't checked the plugs since replacing them about 8 months ago. The previous ones were one heat range too hot (installed by previous owner).

I'm just about to go wash it, when I've finished I'll rip the plugs out and take some pics.

Murcod, I had the same issue a while back. I just drove it harder, further, until the engine gave out and needed to be rebuilt

Runs great now!

Ferwoaza wrote:Murcod, I had the same issue a while back. I just drove it harder, further, until the engine gave out and needed to be rebuilt

Runs great now!

Yeah Murray, I know about yours and that's what I'm trying to avoid. I've had mine for a year now and have tried numerous different things to cure the detonation- even a different distributor (thanks Croz!); but nothing's fixed it. It's pi$$ing me off big time.

The carbon build up would make sense, mine appears to have been a city car it's whole life and has done over 170000km. I've been doing a bit of research and found the USA has regulations on the minimum amount of fuel additives to help clean the engine out, but Aust apparently has nothing and the fuel companies don't have to add anything if they don't want to.

Detonation is a common problem to Ferozas, so the engine design mustn't help either?

Anyway here is a pic of the spark plugs. These ones have been in for around 9000km. If anyone is good at reading plugs I'd appreciate their opinion!

they seem alright maybe a bit to white from running hotter you want them more brown but not dark brown or black. also on the edges of you plug electrodes are they square or rounded

Hi Murcod

A while back I decided 2 run some subaru upper engine cleaner through my feroza.
From memory theres about 90% water in it, not sure what else is used but I've seen heaps of dirty smoke come out the exhaust pipe on some subarus so it must work
A can will cost around $10-12 and u just spray it into your inlet manifold through one of the small hoses.

If u need more imfo let me know

Ruggers, once I cleaned them up with a wire brush they seemed pretty good with no obvious signs of pitting etc. I'll attach a close up pic of two of them before they were cleaned.

James, I've heard good things about the Subaru cleaner from other people too. I would have tried it instead of that other stuff but the nearest Subaru dealer is an hour round trip. So the can actually says it's mostly water does it? Does/did your Feroza detonate a lot or not?

That Nitrox stuff sounds alright too: http://www.griffiths.co.nz/downloads/JEMISC42.pdf

does it have an air flow sensor? on my vit, there was a hole in the intake pipe after the sensor, so the computer wouldn't supply enough fuel for the extra air being drawn through the hole. bp ultimate would fix the problem a bit, but not eliminate it.

just an idea

No Antt, the Ferozas use a MAP sensor- but good call. I've checked all the vacuum lines running to it and they seem OK.

with my old vk i had a small galss of water and dripped it in the throtle body and gave it a fair bit of revs at sam time....and it worked in that so i duno but yeah thats all i know

I've got one of those misting kits for cooling outdoor areas lying around somewhere- they give out a very fine mist. I might have to try rigging up a nozzle in the inlet manifold and giving it a go..... Could be interesting!

murcod wrote:I've got one of those misting kits for cooling outdoor areas lying around somewhere- they give out a very fine mist. I might have to try rigging up a nozzle in the inlet manifold and giving it a go..... Could be interesting!

Too much work, besides, think about how long the hose will have to be!!! You don't need to spray a lot of water in there for a long time. Just use a hand sprayer, the sort of thing you would spray indoor plants with, 'bout 2 bucks at coles. If you put too much water into the combustion chamber, it would contaminate the oil film on the wall, eventually finding it's way into the sump etc.

Just a thought...do you know how good your oxygen sensor is?

I had some bad detonation there for a while and replaced the oxygen sensor. It helped quite a bit. Still pinged with normal fuel but went away with Hi octane stuff. Cause my old sensor was stuffed, it wasn't giving correct readings to the computer which was giving wrong fuel amounts to the engine etc because of it..

Area54, I wasn't planning on trying to drive anywhere with the nozzle in place! The mist they put out is a lot finer than a spray bottle and more likely to make it into the cylinders with the air being sucked in.

Murray, interesting that the Oxy sensor should affect it. I've worked a bit on EFI systems in another job (mainly Commodores utilising the Delco system) and the Oxy sensor is used for "closed loop mode." This means the engine has to be up to operating temp and running at relatively constant revs before it's output is used to control the mixtures. As soon as the accelerator is floored (ie. when I get the detonation) the EFI program reverts back to a set program for the mixtures and doesn't use the Oxy sensor. Who knows what Daihatsu has done though?!

I do know the Feroza only uses a single wire Oxy sensor and my factory manifold was "floating" and not earthed (which means it could give strange readings to the computer). That should be fixed now I've got the extractors on though.

murcod wrote:Ruggers, once I cleaned them up with a wire brush they seemed pretty good with no obvious signs of pitting etc. I'll attach a close up pic of two of them before they were cleaned.

James, I've heard good things about the Subaru cleaner from other people too. I would have tried it instead of that other stuff but the nearest Subaru dealer is an hour round trip. So the can actually says it's mostly water does it? Does/did your Feroza detonate a lot or not?

That Nitrox stuff sounds alright too: http://www.griffiths.co.nz/downloads/JEMISC42.pdf

On regular unleaded it's bad but on shell optimax i dont even notice any pinging

I haven't been able to try Optimax as we don't get it here in SA....

It still seems to be running a bit better. I'll wait until I refill with my normal BP Ultimate before I say it's improved though..... and then I'll try advancing the timing.

If I get bored on the weekend I'll running the water mist through it and see what happens!

Don't be scared, have used the water trick on many old clogged up shitters before. Easiest method is (i know this sounds rough but it works) to connect the vehicles washer bottle hose to the intake manifold somewhere (vacuum port or clamp it in between one of the intake hoses) and go for a hard drive while intermittently operating the washer button.
Give it shit then squirt a heap of water in, it will bog down but keep thrashing it. Couple of laps round the block will do wonders!
Wouldn't try this with a diesel , and i can't recommend any anti-bug
additives for this treatment.

Just a quick few pointers on this topic, an oxygen sensor is not the main sensor that controls air/fuel ratio, it is only a trimming device and is only capable of controlling about 10% of ur air/fuel ratio.

MURCOD, try a product called a flash lube kit, we install them on cars that we convert to gas to help lube the valves. I installed one on my lux (with an injected holden 5L) and plumbed the hose into the ported vacuum pipe on the throttle body, and instead of using the lube i fill the bottle up with water. They have a adjustable tap on the side of the bottle so u can meter the amout of water entering the engine, my motors done around about 16,000kms and i recently had the heads off to do some porting and the combustion chambers are still like new.

Got any other Q's just ask.

ZUK-16V wrote:MURCOD, try a product called a flash lube kit, we install them on cars that we convert to gas to help lube the valves. I installed one on my lux (with an injected holden 5L) and plumbed the hose into the ported vacuum pipe on the throttle body, and instead of using the lube i fill the bottle up with water. They have a adjustable tap on the side of the bottle so u can meter the amout of water entering the engine, my motors done around about 16,000kms and i recently had the heads off to do some porting and the combustion chambers are still like new.

Got any other Q's just ask.

Sounds interesting- what was the reason you fitted it to the V8 for?

I'd be worried about the water leaking out while the engine was stopped and filling a cylinder or four overnight!

the water can not leak into the motor over night as it relys on engine vacuum at mid-wide open throttle to draw the water in. The reason why i said to plumb it into a "ported" vacuum source rather than any other vacuum source is so that water is only drawn into the motor at higher rpm which =: higher rpm=better atomising of the water=better distribution through out the motor= better results.

Just an update- the detonation has improved to the point where I can't detect it anymore.

So the Techron 5000 and/ or the Nulon has made a difference. I'm still running 98 octane and retatrded timing, but it is progress in the right direction.

Still investigating setting up some sort of water injection to give it a good clean out.