Hi, My issue started late 2022 when the car would stall when I’d push the clutch in to come to a stop and the revs would just die but it always starts first time every time. The car struggled to maintain a regular tick over but following rubjohhy 16v setup guide I spent the winter going through each step. I replaced vacuum lines, plugs, leads, ISV, rotary arm & cap, CO2 adjusted, 3 sensors on side of block changed and probably much more. All wiring was checked and repaired where require and it ran better(not perfect but much better). Then I hit March/April this year (weather warmed up?) and the issue went away, well I thought. Now it’s getting cold again it’s starting again. It starts fine and will run on the drive and Rev free without an issue. And when I start driving at first it’s fine but when it gets to around 50% warned up ever time I press the clutch it dies as before, I can prevent this by holding the revs up above 1k. This will continue until it’s warmed up fully when it won’t stall but continues to hunt. I’m pulling out what little hair remains so any advice would be much appreciated.
Break in the wiring to a water temp sensor on side of the head? The wiring can get pretty brittle in this area. Mind you not sure this would explain the "hunting"
I had this issue with my mk2 8v, it would cut out intermittently when clutch down approaching a junction/roundabout etc. In the end I found the ecu relay to be dodgy, problem solved after that. Hunting issues is almost always down to the ISV, have you checked the wiring to the ISV and gave it a good clean out/soaking overnight?
hi, I had the ISV off the weekend and to be honest it was still pretty clean in there. However, i ran it in petrol and flushed it several time and it’s gleaming in there now.
I have this morning disconnect the 5th injector and it’s made no difference whatsoever. Is this the response I should expect when doing this?
Doesnt the 5th injector just operate at the very outset of starting? Would not impact on hunting or stalling when clutch put down? Mind you there are far more learned people on this forum than I.
You haven't said but I'm guessing it's a 16v KR? As it's winter is the issue just cold related or is it more when it's wet? So you say it will idle fine on the driveway: How long have you kept it running? If you start it and run it on the driveway and keep it running until it's fully warm, the thermostat opens and the fan kicks in does anything change during that process? What RPM does it idle at, (I think it should be close to 1k anyway, I'm sure it's 950 for an 8v Kjet) so is your idle speed just too low? You say when you press the clutch it dies, I assume it's nothing to do with the clutch but what you mean is it just won't idle. You've replaced the Vac lines, but I had an issue on my old 8v where behind the inlet manifold there's a fatter moulded rubber Y-piece. It was actually that which had split. I found it's the same on an early Porsche and got one off eBay. I don't think a 16v has the same part. But with it running on your driveway, 'carefully' spray an accelerant (carb cleaner or even WD40) around the engine bay, following the vac lines. If the idle speed increases this will show if you still have a vac leak as the system will have sucked in the accelerant. A vacuum test is like an MOT, only good at the time it's tested. Faults can develop at any time, even if it was previously fine. General rule for K-jet is if you don't pressure test it, then anything you do is guess work and pointless. You need to start by running the appropriate fuel pressure tests to find out exactly what's going on. But I do find this chart very useful. Good luck!
Thank’s for the reply and your correct in it being a KR. Regards wet or winter it’s probably both. When it was wet early this month I used PTF spray to damp seal things and that was cured by this. Now that it’s cold and not rained the last week or so the irregular tick over still remains and this is also regardless of time of day. When it’s on the drive running it hunts until fully warm when it stabilise, it will the happily go through the cycle of switching the fan on and off without over heating. It would idling at 1100 reasonable stable and show fluctuation between 960-1020 on the digital clock. I’ve change the o ring on the tick over screw and the revs are between 900-1080 any lower and it will cut out when driving as before. When first started from cold the revs sit at 1500 on the speedo, this never happened during the summer where it would always sit at 1100 on the speedo whatever the cars temp. The revs are slow to come down now where as before they would drop nicely back to tick over. I’ve sprayed easy start everywhere literally everywhere to the point that I’ve used 2 tins but not had a hint of increased revs. I’ll try again tomorrow with WD40 just to mix it up a bit. If by pressure testing you mean the fuel system I did that during the summer when I had starting issues at that time the fuel pressure was just over 5bar (the fault was the none return valve). I will work through the chart you posted tomorrow. Regards
Hi, I have no idea how the 5th injector work so thought I’d give it a go. As you’ve point out though there was no noticeable change. Started first time, ran at same revs (1500 when first started) and pulled away just as well as it always does.
I'm not sure about the K-jet but when you say 3 sensors changed I'm presuming that includes the coolant temp. sensor/the infamous blue sensor on my 8V anyway?
Ye, there the same. I think they are for the dash temp, ECU temp and ISV. I’ve rotated them and I get the same dash temp read out on all 3 so assume their all good.
With regards to the revs not dropping back I had this recently on my KR. Would intermittantly stay at 1500. Was the throttle shut down switch on the throttle body. Or rather the accelerator cable sticking when returning the cable to stop/micro switch. Get someone to press accelerator while you check the throttle switch is being touched by the stop nice and gently. It might be confusing the ISV??
will give it a once over tomorrow. I was going to look at all the wiring in and around that area. I know I’d did a repair in that area before but can’t help think it was on my previous 8v.
Granted, I have an 8V but your issues and mine are not completely unrelated: When I first got the GTI it was not running at all well including cutting out/hesitating after the warm-up period had elapsed. Through a process of elimination I have improved it by 80-85%. The usual suspects were attacked and eliminated: Fuel Pump and Filter Coil Spark Plugs HT Leads Alternator - I was getting slightly low voltage readings so I replaced it just in case the lower voltage was causing an issue. Distributor Cap Rotor Arm Coolant Sensor ISV Vacuum Hoses Replaced Throttle Body Inspected and Cleaned - they can gum up ECU, Wiring, earths etc. inspected/cleaned/repaired - I did found a couple of dodgy earths and poorish 12V connection to the ISV. Main engine loom opened up and inspected and re-taped (nothing found) There are only 3 avenues left for me to attack 1. Distributor / Hall Senders - I have a new Bosch Distributor that will be installed. Cousin was to assist me with this last month but he bailed. 2. Inspect throttle body wiring, micro-switches etc. (You're having a poke around there now). 3. AFM - This has been opened before without a shadow of a doubt but I'm reluctant to touch it - last resort I will. In your case, I think one of the differences is that you have a Warm-Up Regulator (WUR) on the head - is there any chance that your WUR is not working like it should and screwing up what should be the normal running temp. condition. If my memory has not failed me there is a coil/diaphragm/seal within these that can go for a burton. I did have a KR but it's been a while to say the least. Robert
Just a quick update. over the weekend I was spraying brake cleaner around the air box area and specifically the cut off/over run valve. Every time I gave it a good dose of cleaner it would drop heavily and a couple of times cut out. I covered the warm air inlet to the air box just in case but it made no difference. Anyway while I had the valve off I connected 12v and got a very positive click when connecting power to it. I put it back together and thought knowing the pipes to it don’t usually have clamps (and I haven’t that size) I put several tie raps round the pipe to secure them. It then seemed to tick over more stable the last couple of days but today it’s back to square 1. My thinking is now, if spraying brake cleaner in that area and it gets the response still could the seal between the metering head and air box be a probable course?
pull the plug off the over-run valve and see if that helps. air leaks around the airbox are ok if they're before the metering flap as any air that gets in will still be metered by the flap, though it'll be unfiltered of course. worth having all the rubber pipework off from the meterign head to inlet for a good look for any cracking in all the folds, hard to see when in place
