944 FUEL SYSTEM DE-CARBONISER ??
- Thread starter Jinxy
- Start date
bmnelsc
New member
In Canada it is a popular "service" to add on to your vehicle during the big services - 48K etc. It is of course extra cost and is only described as preventative - no cures guaranteed. Infiniti dealer is the pushiest but when you quiz them on it they admit that is not part of the required services. Also - the Infiniti manual recommends AGAINST any fuel system cleaners or additives (but oddly enough - they sell Infiniti branded fuel system treatment now). In general - if you use a premium brand of fuel there are sufficient detergents, etc. to keep your fuel system as clean as it need be.
So - snake oil is pretty appropriate description - if you are serious about cleaning your fuel delivery - pull your injectors and give them a good soak....
So - snake oil is pretty appropriate description - if you are serious about cleaning your fuel delivery - pull your injectors and give them a good soak....
Come to that, what did they actually claim to have done? This sort of wording can be used to describe a lot of stuff. Was it some sort of squirt-through liquid treatment, or a proper job of dismantling, insoection, cleaning and replacement of components as necessary? Any 944 which has not had the head off for a decade or so will benefit from being decoked and may very well benefit from an injector overhaul or replacement (and a new head gasket, and tha valve guides doing, etc) but that's actual engine work, not a 'treatment'.
Fred Hindle
New member
I think it was about £70 to have the treatment. the magic word was 'Nano', everything is 'nanotech' today, the buzzword to get you to part with some money. What the treatment doesn't do (and it wasn't claimed to do ) is keep the system clean. Probably a 'Get it through the MOT' treatment, especially on low revving automatics where the catalytic converter doesn't get up to a working temperature.
Whatever happened to RedX?
Cheers,
Whatever happened to RedX?
Cheers,
stevie d
New member
Here's a link to the Terraclean website which includes a video extract from the Wheeler Dealers episode where the tall man uses the cleaning system . It details the before and after results of the emissions from the jag . Before treatment approx 0.65 % vol CO & 540ppm vol HC . After treatment approx 0.55 % vol CO & 76ppm vol HC. http://www.terraclean.co.uk/video.html
Veerzigzag
New member
Doesn't cost much to put a bottle of injector cleaner into the tank every few thousand miles when fuelling up. The best way IMHO of cleaning a fuel injector is to run the maximum amount of fuel through it from time to time, thus flushing away any deposits. You can do this by driving very, very fast. But then I am an old git and therefore allowed to do that.
Veerzigzag
New member
Postal refurbishment of injectors is about £20 each inc VAT, and there are various postings that suggest cleaning the air intake measurement gubbins is a good idea. If the 944 is not running very well, that's probably a good plan. My 2.7 (155k miles) also ran much better than ever before when the TDC and speed sensors were changed - inadvertent replacement when a mechanic mangled the old ones during a clutch change. 2x new sensors on eBay were cheap.
+1 for injector cleaner...I regularly dose mine with Redex Injector Cleaner and I could convince myself that on tickover in particular it's improved. So on the whole a good thing?
However, since the warnings about the effects of increased ethanol content in 95RON fuel, I've switched to Shell V Power (98RON, lower ethanol), which is supposed to do the same sort of thing. Again, I could convince myself the car runs better on it...maybe no need to use Redex now?
However, since the warnings about the effects of increased ethanol content in 95RON fuel, I've switched to Shell V Power (98RON, lower ethanol), which is supposed to do the same sort of thing. Again, I could convince myself the car runs better on it...maybe no need to use Redex now?
GlennS
New member
I avoid Shell "enhanced super-whizzy" fuels like the plague. There's no particular science about it apart from the fact that I am old enough to remember with horror "Formula Shell" and its magical engine destroying properties in the late 1980s. Once bitten, twice shy etc. and I can't bring myself to trust them. I do use other people's "Super Unleaded" these days due to the ethanol content issue.
Several years ago i had the injectors cleaned by a Bosch centre on my BMW 530i. The car had covered about 180k miles so I thought there must surely be some benefit. Unfortunately not. Economy (measured an improvement of less than 1 mpg) , throttle response and outright acceleration all felt the same as before the clean.
The clean involved the injectors being put on a flashing machine for about an hour. According to the Technician the flow rate of the injectors were 62, 63, 62, 62, 65 and 64cc. After clean all were 68cc.
The clean involved the injectors being put on a flashing machine for about an hour. According to the Technician the flow rate of the injectors were 62, 63, 62, 62, 65 and 64cc. After clean all were 68cc.
Veerzigzag
New member
But then there was a big problem a while back with OEM petrol (Tescos etc), coating valves and making them stick in the guides. All to do with additives, of which Shell V-Power boasts a lot.
Tesco's posher fuel is actually 99 octane (= 4 star if you are as old as me) and only it and Shell V-Power have this rating in UK, the others being mainly 97 (the legal minimum for "super-grade-petrol") or 98.
I understand that the higher rating makes no difference when the engine is running fast, but prevents pinking at lower revs under load (when you should have changed down anyway).
Or do the complex engine management systems back off the power (less spark advance) across the whole rev range if they detect the odd pink at lower revs?
Is this adaptive in real time, or is there a long delay during which the engine effectively produces less power?
Maybe it's best to use the cheapest fuel to avoid additives, and bung in a bottle of detergent "injector cleaner" every few thousand miles???
GlennS
New member
The 944 was designed for 95 RON, I suspect at least in part because its largest market was the US where their fuel is a bit err... well... Modern engine management systems adapt but I am doubtful whether the early system in a 944 is capable of such jiggery-pokery.
Oddly enough, I don't use Tesco fuel either [
] Or at least not in the 944.
Oddly enough, I don't use Tesco fuel either [
] Or at least not in the 944.Veerzigzag
New member
Interesting numbers. Bosch quote their injector flow rates in the region 150 gm/min to 450 gm/min and the lowest of those rates equates to around 50kW of engine power. You can work the numbers out for your own variant of 944, but it implies that the injectors are supplying fuel into the engine at about half their overall capacity which sounds like a reasonable design parameter. Improving max flow by a few percent is not going to make a lot of difference, and I wonder if an uneven spray pattern makes a lot of difference either, when the droplets of petrol get into the combustion chamber.
Well, I would go for an Italian tune-up if the roads weren't in such a disgusting state!
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