I'm having issues trying to figure out the action of the WUR. As I understand it the unit is basically a bimetallic strip with a heating coil around it. The coil resistance is varied from model to model to alter the heating time and final temperature in order to influence the amount and rate of change the bimetallic strip bends. This in turn changes the amount it loads onto the spring under the diaphragm unit, changing the amount of additional pressure needed from the fuel line to allow fuel to flow out of the unit. Is that basically right? Assuming so, I have 2 questions. I know the coil resistance is crucial and is carefully set for each model but are the metallic components the same for all similar variants of this unit? And secondly, I have been led to believe these can easily be recalibrated with a fuel line pressure meter but I can't see how. There seems to be nothing to adjust them by? How is this done?
first part sounds right to me but im no expert! 2nd part the 8v ones are tricky but can be adjusted by tapping the bit round the back in and out (yes you have to take it apart if you tap it too far!) 16v ones are easy, drill a hole in the brass dome bit and this reveals a grub screw you can adjust to change control pressure
looking at google not the same unit, 0438140118 is 1.8l version and 0438140011 is 1.6. i know the fuel maps on the 2 units differs supposedly the 1.6 one is better iirc
if i recall correctly they are different inside, but you might want them to be. i.e for a slightly richer fuel curve or whatever. both the metering head and wur are different between 1.6 and 1.8
John lol you seem to be talking in riddles here... from what i gather 043 814 0011 will work in place of 043 814 0118, correct?
it will physically fit yes, but the fueling might not be correct. you may find that actually that is fine e.g. if the profiel enriches the mixture and you have supporting mods etc to match think of it this way, its same as if you put bigger fuel injectors into an EFI car, or put a higher pressure FPR, or a different MAP etc. may not work but you may be able to tune it etc
correct me if i am wrong but that can then be compensated with the CO adjustment screw on the metering head, my car does have a 278 cam and bigger valves. so that could work to my advantage
exactomundo! you might prefer to use the 16v WUR instead as you can use the grub screw I mention to adjust the fueling a bit more finely, you often see people talking about using an Audi WUR for this purpose but I bevel its the same as the 16v one anyway. The only problem with it is you can only make it perfect for 1 spot in the fuel map if that makes sense, the adjusting only moves the whole curve richer or leaner it doesnt change how the fuel is delivered if that makes sense. same as mk1 owners always going on about the audi throttle body as its bigger, the mk2 golf ones are the same size so also a good upgrade and easier to get if you can find a kstar+fuel kit those are the best thing for kjet tuning as you can fiddle with both the ignition map and the fuel map all thru the rev range as it uses an injector inline with the wur feeds to allow you to adjust the pressure at all points of the map to suit your engine. normal kstar only do the timing see
For what it's worth Shaniel, I have 2 of these units here taken from working motors. And what do you know, 1 of them is 0438140118! It's on ebay listed as "028 133 403" at the moment if you find you need to get one. My own understanding of the mechanical side of this is not as good as rubjonny's but I have found out that the overall working pressure is arrived at by a combination of the adjustment at the pressure regulator on the metering head and the pressure set by adjustment of the WUR. If the adjustment of the pressure regulator is out of whack then the WUR is no longer giving its best. Electrically I can say that it all depends on the value of the heating coil being in spec. This varies from unit to unit and assuming, as I believe, all units have 12V across them all the time then it dictates the rate of warm up and the overall final temperature the bi-metallic side reaches. Ultimately the engine temperature will come into the picture too and I think swamp the effect of the coil but is will still offer a little effect. These coils seem to be 5% or 3% at best and overall the system is not brain surgery, just a fair approximation during the warm up period. We have seen people here take the line that units are actually fairly swappable. Here is a useful YouTube link where you can see someone adjusting pressures on a Mk2 GTi. Anyone have any idea of how different a 028 133 403 A (0438140073) version is from the earlier 028 133 403 (0438140118)? I'm pretty sure the 073 'A' is 1.6 and the 118 is 1.8 16V.
