Thats a good link! The system I think you have a prob with is the Cold Acceleration Enrichment. This page explains the system BUT, UK cars are different. Instead of the potentiometer on the side of the sensor plate, you have the vacuum switch. I don't have my 16v anymore so I can't remember if they do actually have the vacuum switch unit, or whether the ECU gets it's input from the vacuum hose connected to it. On 8v engines you can clearly see the vacuum switch on the side of the airbox. I will check the photos of my car later at home. Anyways, with the engine started from cold, pull off the fifth injector plug (or pull it off first) and attach a test light or multimeter. Then blip the throttle, and you should see a voltage each time you rev until the engine gets warmer then it'll stop. I'm not saying this is the cause of ya prob, but its well worth checking out.
gti..yeah i'll do that test in the morning when its cold about the 5th inj enrichment..it goes alright if i nail it , its the the transition between idle and driving where it stumbles, so that kinda doesnt sound like it is there a way to make the wur richer for the start up?? boviously i have set it to be 48psi and the correct mixture when hot..but is there any control over cold
It is the transition that the cold acceleration device helps to an extent. It adds fuel to cope with the initial gulp of air when you put ya foot down. Like I say, may not be the cause. About the WUR, no you can't change the mixture during warmup. The control pressure warmup adjustments are predetermined by the way the bimetallic spring bends, which is why I mentioned swapping for another one just to test (should be one in a breakers yard for small cash). When the engine warms up, the heat of the block takes over to heat the spring.
Pigbladder - You can join my 'I hate K-jet' club! Good luck with it, I've not really got any more ideas than have already been suggested but will be keeping a keen eye on this thread. I take it you have control pressure set at hot idle to 48psi and system pressure around 5bar, have you reset the CO as well? Does sound awfully like a WUR fault to me too, doubt it's the pump or accumulator, I changed mine over last week for a known good secondhand setup and it made no difference!
yeah stu..i did all that im reluctant to buy a 2nd hand wur as you never know for sure if its dodgy i'll burn it if i cant fix it
Are you sure that you have not got an air leak somewhere ? That would really weaken the mixture from cold, but as it got warm things expand and seem ok. Spray carb cleaner around the inlet track from cold and listen for rev increase.
rite back again, didn't get round to testing the cold start valve for spray. however, i did test the water temperature sender(brown plug on side of head) and it measured 64.1 Ohm resistance with the engine warm and didn't drop at all. also left the car outside my GF's house for 4 hours(it was good! oh yeah) and measured the resistance of it before starting it up(from cold) and it was still 64.1 Ohm, so it seems like the resistance hadn't changed between the car being hot and cold. makes me think its dodgy... oh, i'll test the 5th injector tomorrow. i drove back from GF's house(with the engine cold) without the water temp sender plugged in and it made F**k all difference! i have anothere on in my garage that i measured the resistance of when i ran it under the hot tap and the resistance of that one seemed to get higher with more heat. i guess it should do that pigbladder, have you tried unplugging the 5th injector and driving the car from cold? just a theory, but if the car starts from cold and idle's ok, doesn't this mean that the ISV will be helping it idle? so theoretically if i unplug the black/red wire near the coil and unplug the isv and then see what it idle's like hot and cold, wouldn't this make it easyer to diagnose a faulty warm up component? doesn't all the isv do is help the car idle? it should idle without it plugged in tho rite? Edited by: bigfatpixey
Bigfatpixey, sounds like a poop sender then. You could try taking it out, putting it in a pan with some water and boil it up to see if the resistance changes (although it sounds like it won't). Deffo get I new one I recon. Yes the car should idle without the ISV when warm. Pigbladder, even though you don't want to buy a new part, you are kinda stuck. You'll never know for sure unless you do change it. Inside they are a really simple setup. I've nabbed loads from breakers in the past. Nice and pocket sized
I know this sounds *too* obvious, but are you absolutely sure that the plug leads are good? What you describe sounds very much like a dodgy plug lead and (from experience) can be mistaken for a fuelling problem.A weak sparkwill have trouble igniting a mixture under any kind of load; yet it can ignite a low-load mixture ok - i.e. even at high RPM if there's no load. I would replace all service ignition parts anyway - leads, cap, rotor, plugs.
What is the lifespan of a coil? I was thinking of getting a new one, to set the car up, since I have plugs, wires, dist, cap, rotor all new.
golden..it starts on the button and revs around to 2k then gently settle to around 1k or maybe a tad over after ajusting the wur and control pressure it didnt afect that at all...in fact suprisingly it only knocked the co out a touch i was thinking would it make a richer start up if i took the wur apart and bent the strip a bit, then reset hot to 48psi Edited by: pigbladder
It sounds more to me like you might have an injector spray pattern problem. Have you check the injector pattern? Also, years ago I came across a mint cabrio gti with a very similar problem. After checking all the fuel and ignition system the head came off to reveal that the back of the inlet valves were covered in fuel/oil gum. I complete decoke completely cured the problem, what was happening was as the fuel was sprayed at these horrible valves it was initially soaked up then just dripped badly into the cylinders. The inlet valves looked worse than the one on the left before cleaning.
pigbladder, do not bend the strip inside the WUR, it is made of bi-metal and will not like it !! You can have the same adjustment effect by drifting the spiggot it is mounted on in or out...
golden, the injectors are recent and the head came off last year, it gets regular redlining and i steal inj cleaner from work as often as i can so it "shouldnt" be that 150pdgti...can you explain a bit more details please
no jetta, im pretty sure its okay in there, anyway if it was coked up surley it would run slightly better after a good blast than when ive poodled around town for a few days
