16v fuel accumulator options

[bmwcompact 10]

The fuel accumulator for the 1.8 KR engine is 431 133 441C ( I believe to be: Bosch 0438170027 or 0438170040 or 41), and for the 2l 9A engine is 431 133 441 (I believe to be: Bosch 0438170051 or 52 or 0438170061 or 62).

 

Its my understanding that the function of the accumulator is to smooth out pressure fluctuations in fuel supply and to ensure sufficient pressure is maintained in the system to ensure immediate start up. I have however read that some owners have operated engines without an accumulator and experienced nothing more than the inconvenience of cranking the engine several times to start: they have reported the engine runs fine! Can this be true-has anyone a 16v corrado without an accumulator?

 

I would welcome input to a discussion on what accumulator can be used on the Corrado 16v.

 

I believe that the KR accumulator maintains a residual pressure of 2.6 bar, whilst the 9A accumulator maintains a residual pressure of 1.8 bar (please correct this info if its wrong). So, would you be happy with a used KR accum on the 9A or more likely a used 9A accum being put on a KR engine?

 

Since they are expensive (typically £80-170), owners faced with yet another part to replace and failing to find a usable secondhand unit might be tempted to try the cheapest new Bosch accumulator they can find. I cant find any information on Bosch accumulators (residual pressure): does anyone have a source? Has anyone tried one of the cheaper Bosch units eg 043 817 0007 @ £80 on a 16v corrado?

Edited March 8, 2013 by bmwcompact

[bmwcompact 10]

bump

[davidwort 0]

I wouldn't fancy running a 16v without one, I'd imagine starting would become really annoying, given how long it takes me to start after working on the fuel lines and dropping the pressure out of the system. Also, given that the system is a constant injection system I'd imagine fuel delivery may be affected too if pressure can fluctuate. I've never chopped one apart but if it does act as a pressure control unit then I'd imagine the correct part would be pretty critical to fuelling.

[davidwort 0]

have you asked on club GTI?

[bmwcompact 10]

Thanks for your reply David. Googling takes me to many forums in the UK and abroad. Since Bosch injection systems have been fitted to other marques eg Ford, volvo, porsche, then I have read about non corrado setups. I have gained a general impression that the accumulator is not so important and need not be the one originally specified by the manufacturer. I am not a member of any other forum so have not asked the question elsewhere.

 

There are many sites showing a cross-section of an accumulator and explaining its function (it contains a rubber diaphragm and a helical spring). I believe that other than physical dimensions and hence their volume (most appear to be the same size) the only other difference in accmulators is the spring stiffness and hence the residual pressure that they maintain in the system. Its the pump that produces the pressure in the system not the accumulator, and its the metering head that controls/maintains the correct pressure to the injectors when the engine is running. Hence I believe the main function of the accumulator is in allowing easy starting apparently especially when the engine is warm. I cant believe its important whether the residual system pressure is 1.5 or 2.5 bar.

 

So thats the theory and my conjecturing.

 

I was hoping some petrol heads who have swapped engines and components between golfs, sciroccos, passats, corrados would tell of their experiences whether successful or not.

 

I ask this question simply because cost of ownership can be high and the possibility of using other more available/cheaper parts (whether new or used) ought to be of interest to forum members.

 

I might add the same thoughts occur with the ISV. There are vauxhalls, peugeots, citreons, saabs etc with very similar Bosch or VDO valves. I dont believe they are so different (volume of air delivered) yet I have found no information to show which will function on a corrado. (I might add there are posts for other vehicles explaining how to retune an engine to remove the need for an ISV).

 

In both cases I don't consider the function being performed to be so precise, the component so complex that the cost is justified. (Think what complex electrical devices can be bought for £150, the cost of an accumulator).

[davidwort 0]

that's interesting, as 16v ISV's are hard to come buy (in comparison to the 8v counterparts) I tried running one on my valver some years back, and guess what, idles perfectly, hot or cold, summer or winter, there's just a slight difference in the inlet and outlet positions but it fits the bracket and pipework fine. I'm talking 1.8 K-jet here, the metal bodied VDO ISV, not the 2.0 16v black plastic (bosch?) isv.

But I remember some time ago 'CrazyDave' asking about ISV duty cycles, so the ECU's must be match to the ISV electro-magnet in some way, bit beyond me though :)

 

your explanation of the accumulator sounds good, in which case a mk1, early mk2 8v or even an XR3i or capri one would probably work fine, probably best to get one from a 4 cylinder basic K-jet though if possible, plain K-jet does seem to run at a high pressure.

 

I'd register and look into the 16v section on the club gti forum though, loads more work done on 16v engine swaps and so on in there, some very knowledgable users, in particular toyotec? he's turboed an ABF 16v and seems very clued up on the tiniest of details in spec variations on 16v engines over the years

[bmwcompact 10]

I have spent some time on the net today researching this topic. The following quote from an American site is just one of several I have found. It says what I've been suggesting:

 

'The fuel accumulator is only installed to smooth out any minor fluctuations in your fuel pressure (similar to a shock absorber) as you drive your car and to maintain a residual pressure in the fuel lines after shut down to help during a restart. It is basically a canister with a rubber bladder in the middle, a spring in the top half and fuel stored under pressure in the lower half. There are many Bosch style fuel accumulators on the market that are interchangeable between vehicles. As long as the connections are similar and the internal capacity of an accumulator is relatively close – it will work. For example I often install one designated for a 6 cylinder Volvo on 911 Porsche – at half the price. Search on the internet under Bosch Fuel Accumulator rather then one for a specific model car and you’ll see lots of photos that will help in identifying a substitute. By the way the one needed for a Porsche, Mercedes, BMW - V8 engine is a big mother and they are all pricey....'

 

If you are a believer, this suggests the course of action to save some money. If you are not its as you were.

 

I also have read today on the GTI Forum of several VW owners who have removed their accumulators at MOT because of corrosion-it was a fail or removal -and they have never replaced it and report no running issues!

[bmwcompact 10]

Has anyone any experience they would like to contribute?