Hi All, Not the usual WUR question, ie. what is it, what does it do, what is the Stealth modification etc? My question is what does it indicate if my car cold starts in the same cr@ppy way whether the WUR electrical connection is connected or not? I have tested the resistance across the WUR heater element as per Haynes and gt 24 ohms which is within tolerances. Also, when cranking or running the engine at idle the connector gets a constant 13.7 volts to it. This drops very slightly as you rev the car but only by 0.05 volts or something. My thoughts are that it means the heater/bi-metallic strip in my WUR is knackered - could this be the cause of my on-going cold start problems? Any answers much appreciated!
I'm afraid what you've tested doesn't tell you much. You've checked the electrical side, which from what you've said checks out ok. The only way to tell for sure is to measure the control pressure during warm up.
stu,if you can wait till mines been set up (dodgy brakes to sort ) you can lend my wur and gauge if you want or where do you live? i'll stick the gauge on it for you, im between stanstead and cambridge Edited by: pigbladder
For cold start it does not matter whether the electirical connection is made or not - what matters is the value of the cold pressure that the WUR is placing on topof the metering head plunger. Once started the electrical connectionto the WUR simply supplies a current to a resistor inside the WUR, this causes a bi-metal strip tobend andincrease thecontrol pressure, heatfrom the block will also increase the control pressure up to the upper fully warmed uppressure setting. So for a good cold start you need the following :- 1) A good battery for fast cranking and fat spark, 2) A WUR that gives the correct control pressure at cold, 3) Good spark plugs, Disy cap and leads and the engine timing spot on, 4)The metering head disc set correctly and allowed to move the metering plunger smoothly and freely, 5) Correct system pressure. 6) Good spray pattern from the injectors, 7) Cylinder head free from carbon, 8)No air leaksin the inductionside, ie injector o rings, inlet manifold gasket, throttle body gasket, auxiliary air bypass valve.
Hmmm... that sounds like another possible cause of the poor starting out of the window then! I thought the electrical connection was to heat the bi-metallic strip when the engine was cold, oops! Thanks for all the info
That would be great but I'm miles away unfortunately in Cheshire! Looks like I'll have to get myself a gauge and a spare WUR unless you could post them to me to borrow and I could post them back when sorted (I would cover costs of course)? Edited by: Stu
The thing with the WUR is its a differential pressure regulator. If it fails and the CO is adjusted afterwards the warm running will be absolutely fine but the cold running will suck. Checking the control pressure is the only way to tell.
That sounds familiar, could well be my problem! I could check control pressure with a fuel pressure gauge plumbed into the correct line couldn't I?
Yes you can, read this thread and this thread. and if you going to have a go, make sure you get the correct gauge
Ok cheers for the info, will have a good read of those threads before I attempt anything, don't want to make it worse! Anyone in the North West got a gauge lying around they want to lend me...?
