Tried to write this post a couple of times but always ends up as an essay so I'll try to summarise in bullets: Background: 1991 16v Has had various mods including head ported to fast road spec after sitting for ~1yr was very low on fuel Car ran fine before it was laid up. Also ran fine for first few weeks after getting back on the road. Past few days I noticed a slight misfire - which has worsened to juddering and occasional cutting out while driving. Seems to happen mostly when accelerating uphill. Car has had conversion to mk1 fuel pump by previous owner per this post: https://clubgti.com/forums/index.php?threads/swirl-pot-replacement.286190/ I've checked plugs: biscuity and seem OK to my amateur eye last replaced in 2013 according to receipts that came with the car Dizzy found some oil inside it. Cleaned it out, no improvement found some evidence of arcing on cap 'contacts' and rotor arm - I gently scraped these clean. No improvement fuel shell 99 Since back on the road I've gone through 2 full tanks each with half a bottle of redex injector cleaner stuff fuel pumps in-tank replaced 2016 under-car replaced 2017 - mk1 - with different swirl pot per post above Next things I plan to try: replace fuel filters from reading it seems like there are 3 filters but I can only find the big 'can' one that sits under car near pump available Does in-tank filter come with the pump? Is it possible to clean rather than replace? is it even worth checking / considering the one in metering head? replace plugs other? I appreciate this is a fairly complex issue and hard to give advice from afar so not expecting a silver bullet response. I can't afford to throw a lot of money at this to fix it so trying to locate the issue before buying new parts. Thinking I may need to pull the injectors to check o-rings and fuel delivery but terrified of breaking something so leaving that for now.
My 1.6 did similar, new plugs and caps sorted it, for £20 it's worth a try, years ago bought an xr2 that ran awful, plugs looked fine, even cleaned them up to look new, but still problems so swapped to a new set and sorted.
Cheers Dave - got some plugs on the way. Re: caps are you talking about HT lead caps and if so is it possible to replace these without buying a whole HT lead set? These seems a bit more expensive than £20 Dizzy cap / rotor however seems cheap so going to order those too.
While waiting for the new bits I removed the in-tank pump. Filter had a few bits of crud on but didn't look too bad to me. Rubber gasket that seals the assembly to top of tank was a bit mingin though and definitely dropping rubber into the tank so have put one of those on the list to get. Peeked inside the tank and saw some detritus at the bottom but since the pump filter wasn't blocked up I couldn't be bothered to remove / clean out. I did notice that the fuel level float was degrading a bit but again didn't consider this enough of a badness to remedy. Scraped off the loose bits and called it good. Am I being too lax? Is there a chance that crap in the tank could be blocking the filter when the pump is pumpin?
Possibly but I doubt it, I don't thin the pump is that much of a monster. Don't get ripped off by Heritage for the big seal, give your dealer a ring as they're still available
@dodgy is spot on - start with new plugs, rotor arm, distributor cap and underfloor fuel filter. If that doesn't work, I would look at ECU connections/wiring, temp sensor, HT leads/hall sensor/distributor. With regard to underfloor pump, they generally work or they don't rather than spluttering along for a while. I would leave the metering head until last but if no joy with the other fixes, check the potentiometer tracks and reposition it by loosening the screws and slightly repositioning it to cleaner tracks - I think there is a thread somewhere on here about this. I have similar issues with my 8v - To date, I have checked ECU connections and wiring, replaced fuel filter, spark plugs, distributor cap, rotor arm, HT leads, genuine blue temp sensor, ISV, vacuum hosing, re-done a number of electrical connections and grounds. Next on the list is a new distributor and then the metering head potentiometer tracks and I do have a new fuel pump on standby but I don't believe that's the issue.
@saladman I have a mk2 non injection tank and a mk3 gti one here if want to rob the float off either if any use to you.
Thanks all for the input and advice so far. @dodgy appreciate the offer of a float but think I also have a spare tank in the hoard pile so no desperate rush. Dizzy cap and rotor arm arrived yesterday ( from vwspares.co.uk ) so I decided to fit those and see if it made any difference. Both are Beru brand and mouldings / aesthetics were a bit crap but not a problem if they work. Looks like the parts have had some manual finishing to remove flashing / imperfections. Rotor arm is a little taller than the old one but again no major drama. Centre pin is also a touch taller than the old one and no rounded/chamfered edge - I presume to save manufacturing costs. There was a bit of oil in the black cap sleeve so cleaned that up before sliding on to the new cap. HT lead connections all looked ok and gave a satisfying click when plugging everything back together. I also removed and inspected the lead to coil, as well as 12v live / gnd coil connections. Nothing of obvious concern from visual check. I didn't bother doing the under car fuel filter yet and still waiting on plugs. So felt like I should do something else and decided to pop the Big Rubber Boot off the top of the metering head (I think that's the correct term, but happy to be corrected). Not sure how clean it should be but it looked pretty rank so gave it a wipe round to remove the gank. Is the above a problem / unusual / normal / other? I have noticed a kind of humming / resonant tone coming from this assembly when the engine is running (and rubber boot on). I removed the air filter (K&N in original box) - seemed fine on visual inspection. Unsure of age. Finally I quickly checked round all the vac lines that I could see in case anything had popped off or obviously split. Again nothing of concern based on visual check. Started the engine and ran / idled fine. Left it to warm up while occasionally blipping the throttle from engine bay. It seemed like there were occasional misses but wasn't sure if it was my imagination. So I did the right thing and went for a test drive. 20 minutes of mixed traffic / open B road and no problems - pulled well up to 5.5k ish. Not convinced that the issue is fixed and will still be fitting the filter and plugs soon and will carry on testing. Again thanks all for the advice and I'll update with further progress / works
Oh and I did check the various sensor connections on the head and found that the one with the red and yellow wire (I don't know which sensor that is) was hanging on by a couple of strands of copper. A quick wiggle separated the wire from the connector so I spent 10 minutes trying to remove the terminal from the OEM housing before sacking it off and crimping on a blue female (not-)spade connector. Not sure if that will make any difference to the misfiring / running issue but seemed worth doing.
Residual oil is normal in and around the airflow meter plate as the crankcase breather recirculates oily air back into the airbox. Sounds like you may have fixed it but don’t be disappointed if it reappears. Keep doing what you’re doing and you’ll find it.
yellow/red wire is for the dash, so wont affect running. the air metering flap assembly doesnt look right to me, measurements here for std vs motorsport so compare to yours: https://www.clubgti.com/forums/inde...ir-weighing-valves.220566/page-2#post-1952378 and heres a piccy of a 16v one see how yours is a bit thicker round the outside... whats the part numbers on the air flap bit and the fuel bit on top
Sharp eyes on the air metering unit @rubjonny ! I'll have a look for part numbers later and post back. Broke down on the way into work this morning. Ran fine for 25 mins or so then went lumpy and died. While under the bonnet I noticed that I could affect the idle if I touched / moved the plastic hall effect connector body on outside of dizzy. I could get it into a certain position where engine would run nicely, but also kill it. There was still some oil in and around the sensor which I believe can mess with it so I cleaned it up as best I could while in some random carpark. I thought I might be able to remove the sensor assembly by undoing the two screws holding it to the dizzy but seems like there's a ... sensor wheel maybe ... that is pressed onto the shaft so no dice. As a temporary bodge I found something to wedge between the hall sensor assembly and dizzy housing. Got home fine. Current thinking is that this is the culprit of the misfire / poor running. Back home I found this post about replacing oil seals in the dizzy so now have those on order from simplybearings. Nice one @MUSHY 16V I did find a new 'maXpeedingrods' dizzy online for £30ish but unsure of what the quality will be like so decided to spend just as much as some round bits of rubber first
You dismantle the distributor by removing the Drive pinion which is held on with a pin hidden behind the coiled washer you can then pull the shaft and Rotor up through the body to gain access to the Hall Sender, do not try pulling the Rotor off it is bonded on if you have a genuine Bosch unit, don't ask how I found that out !!
@Peter Sears thanks for the tip! I managed to get the dizzy apart earlier and came apart easily as you mentioned above. Weirdly the oil seal in my dizzy is 12*22*7, not 12*19*5 as mentioned in @MUSHY 16V 's post above so I have placed another order with simplybearings At least it gives me some time to clean everything up...
According to paperwork that came with the car it's a DANSK (part number 403440061 from Euro car parts). So, that's a no then Cost was £103.99 in 2016! Also might be being thick but can't find part numbers on the air flap and fuel bit of the air metering assembly - do I need to remove it from the air box / look from where the filter is?
I have in my spares box a new hall sender which I did not need when I rebuilt my distributor as the Genuine Bosch one was fine. If you were having an intermittent problem when moving the wires you would be welcome to give it a try to see if it cures the problem.
Amazing thanks! I'll see how I get on with the rebuild and get in touch if it's still rough / giving problems once all back together. I had been wondering if it's possible to get just the hall sender assy itself. Much appreciated.
