Er. No. Not done that before so not confident. Bit lame, I know. I've had a read of your instructions. Not sure I fully understand but I'll have a go!
Just ordered a timing lamp. Quick question, do I test this whilst the engine's warm or cold or shouldn't it matter?
While doing the HT leads, I'd take a peek at the plugs during a cold poor idle. Misfiring is either too rich, poor timing, poor spark or poor air, so diagnosis can be difficult. I don't know the Kjet system to determine if its too much fuel. It won't be under fueled as a lean state won't hold a low idle. As Toyo said, timing... RJ is always right when it's electrical, read his BASICS guide, it's gold! (John, there are dead image links in the doc - http://www.clubgti.com/showthread.php?195423 )
Thanks for the pointers, the exhaust smells pretty fuel-heavy, so my guess is it's running rich. I suppose that might explain why the car struggles to start until I dab the throttle; I'd guess at the extra air coming in leans out the mixture enough to allow it to fire? What I don't understand is, if it's a timing problem, how did it suddenly occur when I changed the ICV? Current situation report from the original list, anyway: 1) The car sometimes won't catch for ages. The starter's spinning OK. Eventually it'll cough and if you give it a bit of throttle it'll fire up. This is intermittent. It's generally worse when the car's been standing for a couple of nights, although it does occasionally do it after much shorter periods. Still happening, guessing the mixture's too rich perhaps 2) The car will occasionally stall when put into neutral. I think this is the ICV as the revs will dip below idle before recovering pretty regularly, sometimes it won't recover quickly enough and that's when it cuts out. ICV replaced, problem so far no longer occurring. Hopefully solved 3) The very occasionally stalls when standing at idle for long periods of time, for example in heavy traffic. It'll start running rougher than normal, then struggle, then die. Could this also be down to the ICV? Discovered a bad HT lead and a dodgy rotor arm. Both replaced and so far no repeat incident. A bit early to be sure, but potentially resolved. 4) The one I'm particularly concerned about is after it's stalled, it often won't want to start again. When this happens, the starter won't spin as if there's no charge in the battery. I've got dash lights, headlights etc all working without dimming. If I leave it for ten seconds or so, it'll then start again. This does seem to be better, although at least partly because I've reduced the instances of random stalling 5) Rough running and stalling when cold. New problem starting from ICV replacement. Two steps forward and one step back!
+1 (or should that be +100) for Rubjonny's basic checks : http://www.clubgti.com/showthread.php?195423 - idle switch, air leaks in vacuum lines, temperature sensors, timing Maybe try an extra earth from the battery straight to the gearbox or engine for the starter issue.
OK. So I checked the ignition timing. The large diamond looks about right in the centre of the viewing hole. However it is roaming quite a lot. The car is hunting a bit and when the revs drop, the diamond isn't central, ie it hasn't come around that far. I haven't tried adjusting it as it does line up most of the time suggesting something else is responsible. I've also noticed that with the idle screw fully closed the car is still idling at about 1100/1200 rpm. When cold the car has a definite sound of not firing properly. Like a cylinder isn't firing at all.
With a pinch of salt.. Take a visual of your plugs and note any difference on one cylinder, that'll disprove the single cylinder. If there is an unhappy plug, then it might be the jet/injector, (for Kjet others will help) then it would starve the cylinder at higher speeds so the miss would be consistent and the plug would show signs of a lean state. In the meantime, buy a good length of vac hosing, a couple of T pieces to be safe and replace each length one at a time. Splits seem to always happen out of view! It's a relatively cheap exercise and it can't hurt giving things a glance while you're under the hood. Be sure to check in with John, Eddie and the long list of GTIers that will get to the bottom of it.
I also replaced the three senders on the side of the block. If anything this seems to have made things worse!
have you checked out the idle switch and upper throttle linkage yet? if that isnt working it'll give you a hunting/high idle. if idle screw is all the way in that points to an air leak
Hiya, The idle switch *seems* to be working OK. If you disengage it from the arm the engine note changes. The throttle linkage is hitting the switch and hasn't been over-adjusted as the arm still has its full range of motion. I won't be 100% certain on the switch unless I swap it out, though. Agreed on the air leak. It seems pretty clear now that's what I'm dealing with; the fact that it's playing up when hot would fit if it's pulling hot air in from the engine bay. It's particularly bad in traffic when there's no air flow through the bay and I have confirmed cracks in the big hose boot that attaches to the air box. If they're there then there's probably some elsewhere. I'm guessing that I disturbed some perished plumbing whilst I was clattering around in the engine bay. Thanks for all the help and sticking with it, guys. I feel like I'm closing in on the issue now, at least! I'm taking the car off the road to have all the air hoses off it. I guess I might as well swap for silicone whilst I'm there. If nothing else I'm learning a lot from this palava!
cool the idle switch sounds fine then if it makes a difference when disengaged so you can stop worrying about that if injector seats and injector seals have never been touched by you chances are those are leaky, spray round the base of the injectors with carb cleaner or similar see if note changes. also if the seat seals are suspected unplug the thin hose from the breather to the inlet for the air shrouding system and cap this off, this will stop any air leaking past the inserts
I had a good look round the engine bay yesterday. I replaced the air duct boot on top of the airbox as that was cracking plus all the little vac hoses behind the bulkhead heat shield and down by the airbox. Some were cracked but only one was notable split: I've not had a chance to test the car yet, but what's that line for? It feeds into the back of the head from the airbox ducting.
looks liek the vac line from the brake servo hose that splits off for the ecu and the over-run cut-off and cold throttle enrichment valves. main problem with it being split is you have an air leak, so once thats all sorted you'll want to reset the base idle and co
OK, I'm losing the will to live with this, now. Got the car started and it does sound better, however it wouldn't idle. The second I took my foot off the throttle it stalled. After a couple of attempts at trying to get the thing to idle the damned thing decided it didn't want to fire at all. It just sat there. Turning over. If I wasn't having to borrow pool cars and rent and get taxis, this'd almost be funny. Can cars have grudges? Did I offend the effing thing somehow?
The three big sections to the throttle body? I had all of those off when I did the vac lines. Replaced the ducting from the air box. They were a royal pain in the ring to refit, but they did go back on and I'm pretty sure they're solid. I will have another check, though. It's probably time for a list of the stuff I've done: Replaced: HT leads, battery, 3.25mm core vac lines (every one of them I could find), air box ducting boot, rotor arm, 3x temp sensors on head, ISV, idle overrun valve. Tested: Ignition timing, resistance to head sensors and ISV. Lost: Patience, will to live, any residual faith in garages and a couple of spring clips.
