Hello, I have an '86 8v K-jet Mk2 Golf and I seem to be having an issue with running. I have done all the usual stuff like timing (using all the correct marks) using a strobe timing light, replaced dizzy cap, rotor and leads so all seems to be good there. The troubles I am having are as follows: 1. After first start up (and especially when its cold weather) the car doesn't have a very fast idle. Then, if the engine dies straight away or it dies when the revs drop after pressing the throttle, it is then very difficult to start it again. The engine then turns over about 8 or 10 times before it starts again but will still have the characteristics described above. 2. Once the engine has run for a while and is warm, then it will idle fine and doesn't die when the revs drop (i.e approaching a roundabout or braking to a stop). However, it seems to be really flat until about 2k rpm, after which it then picks up and feels strong. It almost feels like its being stangled until 2k rpm and then whatever is causing it ceases and the car pulls normally. Other things to note are that once warm, it idles at about 800-900rpm (mostly at about 800). Can WUR's go wrong? Do I need to set my idle speed higher? Do I need to adjust the CO on the metering head? Any assistance much appreciated. Karl
getting the CO adjusted would be a good start, after that ideally you mwant to gety a k-jet pressure tester on it so you can see whats going on with the fuel system. without this you can end up randomly changing parts for ages before you stumble on the part that was the casue of your problems. A fuel injector test might be an idea, pop all 4 out and bridge the fuel pump relay, lift the metering flap up and check all 4 spray nicely. If you want to be even more scientific about it, you copuld put them into their own container and measure the fuel delivery. Then once you shut off the fuel pump relay make sure they dont drip
If it's very flat up to 2k rpm, I'd say your cam timing could be out. If that's the case, then the work you did getting the ignition timing right is wasted, because it's out relative to the cam. There's a description of setting up cam timing in the haynes manual.
Sorry for the ingnorance Jonny, but is there an established routine for CO adjustement i.e. a right and wrong way so I don't mess it up!
no its easy on a k-jet, sniffer probe up your tailpipe then adjust the co screw. if you look at the rubber boot on the metering head there is a small hole just in front of it, down there is a 3mm allen key grub screw. adjust it a tiny bit at a time, and dont rev the engien with the tool in there.
Just had a look and you can get them for about 75 plus postage on EBay. I read your 8v tune-up guide on Edition38 (which applies to the Digifant engines) and you mention that you can adjust the CO by 'feel' i.e. adjust it until it runs rough then adjust again until it runs smooth. Can this process be applied to K-jet 8v's as well? I could always take it to my friendly garage and get them to test the CO I suppose.
it will get you close, but its not really advisable, better to go for a proper co test if you can. you can get the co meters cheaper if you shop around on ebay
I adjusted the CO screw on mine by feel because it was running like a dog when i first fitted a new engine. It does get the engine running much more smoothly but mine still requires setting up properly. My kjet still suffers from a couple of the symptoms you appear to be suffering from still - mainly cold start related. I've heard the gas testers aren't really much cop though for this based on their sensitivity? Or lack of I could well be wrong though I'm booked in for a rolling road setup in the new year to get it running spot on. Would the fifth injector not working have any bearing on some of these specific issues? Or is that just for extra fuelling at the top of the rev range?
Right, well I suddenly had abrain wave last night and remebered that we have a CO tester at work (d'oh!). I have just run it up on the tester (calibrated and car at operating temp, probe stuck a good way up the exhaust) and I got 0.67% on the right hand tail pipe and 0.97% on the laft tail pipe (its a standard GTi system). So, unless the CO meter is wrong (or I did something wrong), then the results above rule out anything to do with CO. .....
you want to be aiming for between 1.5 and 2% if i'm not mistaken. idle mixture screw has the greatest effect on the mixture at idle, but also influences mixture throughout the rev range, the higher the revs, the less the effect your idle mixture adjustment has. hence why it may be worth richening the mixture up a touch to improve your lower rev performance.
doh! i was mistaken then. sorry i should have got off my **** and looked in the haynes just had a look, you're quite right i was thinking of my old carb motor. sorry dude didn't mean to misinform you. looks like that could explain my fuel consumption then as mine's set to 3% <slaps forehead>
No worries mate. I guess its back to the drawing board - check timing and ignition, plugs etc again - just in case I missed something.
Have you checked all the vac lines? Last kjet i had ran like a pig, till i changed one or 2 vac pipes
Did you calibrate it in clean air? I'd have thought you should get the same result in each pipe, or very close. You only need to measure one, really.
