Hi All, My car is a mk2 16v, and it has never run properly from when I bought it [:^(] Arguably I am stupid for buying a car that didn't run properly to start with. OK, there do not appear to be any air leaks, all of the vacuums are connected and the fuel metering head has been ruled out (swapped for another one). The idle valve also appears to be working OK. Other things that can be ruled out are the cooling system as I have just put on a new thermostat and water pump, and the injector sprayheads are clean and pushed home firmly. The valve and ignition timing are both dead on correct. The symptom is that the car is running VERY lean. I have a wideband lambda kit on there because I am halfway through building a megasquirt, but I haven't currently got time to finish it, so I need to try and figure out what's wrong at the moment. The car is running at something like 15.8:1, and it idles badly. In fact, the idle isn't TOO bad when it is cold, but as it heats up it gets worse. The engine also "hiccups" when it is idling, which also corresponds to a change in the AFR according to the lambda kit. Someone has advised me that the warmup regulator (i think it sits on the side of the head) could have gone wrong - I have been told that this controls the system pressure of the fuelling side. Can anyone please offer me any information as to whether this sounds feasible before I go and buy another one? Thanks, Ajoy.
Hi, it does sound feasible mate, i had the same thing on mine, if you look in the FAQ's i did a FAQ on adjusting the WUR to it's optimum! Second hand ones around 30, i think i still have one spare and it should be pre drilled so you can access the allen key to increase/lower the pressure to the injectors! If you want it let me know, if you want to just test it first then i am happy to send it to you if you cover postage, if it's not that then just send it back, if you are happy then you can but it off me! Can't say fairer than that
Hi Kev, Thanks for that - can you give me a link to the faq please? the faq section doesn't appear to be working on the new site. So could it be that my WUR is not actually faulty, but just not set correctly? Thanks! Ajoy.
Yes mate it the FAQ section does work, it's just have to set the post from the begining on the drop down! here is the link anyway - http://www.clubgti.com/forum/showthread.php?t=81658 As to your question, it could be knackered or arm may have just moved inside! I know the one i have is working though. Of course you need to test the system pressure as well as if this is low, the wur will be low!
OK, thanks for that! Just two more questions - can it be adjusted on the car? I can see my AFR because of the wideband lambda sensor, so can i just stick an allen key in and give it a tweak? Also, when you refer to the "system pressure", do you mean the actual pressure coming from the fuel pump? Thanks, Ajoy.
It can be adjusted from the car, like in the FAQ, you will need a fuel pressure gauge and the system presure is from the metering head to the wur!
You've probably checked it, but it might be worth taking off the crankcase breather hose on the front of the block that joins to the airbox and cleaning it out/checking for splits and vacuum leaks. When that gets full of crud it can mess up your idle in my experience. Also, check the airflow sensor plate is sitting at the correct height in it's bowl as per the Haynes manual instructions, though you may have ruled this out by swapping the metering head.
Oh, should i be also checking the thermotime switch (is that what it is called?!) Is there a faq somewhere that shows what resistance it should have? Thanks, Ajoy.
Thermotime switch is only to activate the 5th injector when the the temp is low! This should have nothing to do with your particular problem!
So the warmup regulator does actually affect the pressure of the injection system, even when the car isn't "warming up"?
What the warup reg does is reduce the pressure from the metering head to the injectors during a cold start fro around 1 minute 30 secs, with reduce pressure the engine will run rich for that amount of time, once fully warmed it has no effect! it like an auto choke if you like!
well if the wur is knackered then it could be stuck on the rich setting, causing overfueling all the time! best to try another one to rule it out, otherwise it's just all guess work!
have you set the C0% (mixture) to 2%? If so have you checked your injectors, are they squirting in a cone shape spray?
Right I can set the CO because i have a wideband lambda, but what do I actually put into the hole? Allen key? flat bladed screwdriver? It's pretty deep and dark in there!
All you need is a long 3mm allen key and adjust it slowly, once you get your 2% on you wideband you should set to go
Thanks for that - I have adjusted so it gives about 14.5:1 at idle. It does jump around a bit though. The car sounds much happier (much less popping and spluttering, and the oil temp doesn't go higher than 92) - I had to turn down the idle speed a bit as well, and it drives a bit better, but it needs an extended drive to see how it runs really. The only thing is that when cruising at about 80, it goes lean again (about 16:1 or so), and also, the enrichment isn't there when I put my foot down. Any ideas on that please? Thanks, Ajoy.
what are you ajusting to get the readings?? i drilled the back of my wur and kept tweaking it ...then ranting up the road to see the a/f ratio, mines about 13.5 give or take through the revs
I am adjusting the 3mm allen screw on the fuel metering head. I didn't mess with the WUR as the problem doesn't seem to be related solely to cold running - it runs crap hot and cold!
