Hello good people, Swapped my butchered Pierburg to a weber 32/34 DMTL since it wasn't worth fixing. (Not even the right model carb fitted!) I have a flat spot and the car is sluggish in any gear if I apply anything more than 5% throttle. I can accelerate from any speed when I very gently apply throttle but if I need to move quickly and stab at it, the car bogs down before gradually opening up. Above around 3500rpm the problem isn't apparent anymore. Should mention the carb came as a conversion kit, new, jetted to a 1.8 I have a K-Jet dizzy and GTI cam and a full Milltek exhaust inc manifold. Car runs on Shell 99 RON exclusively and has done for my 12 months of ownership I've had an MOT garage tune the carb to pass by one of their older mechanics who set my mixture, idle and measured results with an gas analyser to pass the MOT. Since then I've visited a carb specialist who checked the carb. All electricals were reported good. No leaks. Good plugs, dizzy and coil. Exhaust gasses all good. He advanced the timing to around 7 degrees (from the 6 I had set) and said I could likely push to 8 degrees if I wanted more performance. Since there seems to be no where local to me (Peterborough) that can help tune with a rolling road. Does anyone with knowledge of Webers and mk2's know what I could try at home, one step at a time? Appreciate any and all feedback, Andrew
if you havent done so already try removing the swirl pot and blocking the fuel return. if that solves the issue then you can fit a restrictor in the fuel return line. it should have one as standard but it often goes missing and just to double check that was 6 degrees with dizzy vacuum line off and plugged?
Hi Jonny, Thanks for your reply. Can confirm dizzy was set properly. The carb man I went to see believed it could cope with a bit more advance, so remarked the dizzy body at 6 degrees then spun it to about 7.5 and said I could keep going so long as it didn't ping. I'll have a go at what you said with the fuel return line. She does seem to behave better when I pull the choke out a touch so if I had to guess I'd say it might be fuel/air delivery issues. Andrew
Right. As I was fixing other issues with the car today I had a go at bypassing the swirl pot. I used a spare fuel filter that came with the new carb so that I had a straight line from the engine mounted pump to a filter to the carb. Started at warmed the car, went for a test drive. At first it seemed like there was more of an immediate response from the car lower down the rev range. 1500rpm to 2500rpm certainly didn't have as much hesitation. From 1100rpm to 1500rpm did still have a bit of a sluggish feel. Although I might have my expectations set far too high for the amount of torque on tap form the motor. Something I had been meaning to ask though. I'm not 100% sure that I'm not hearing pinging/pinking/pre-ignition, whichever it's called. When I put my foot down to about 50% throttle to pull away from say 30mph in 4th gear, there is a noise under the drone of the exhaust that sounds like a biscuit tin full of small ball bearings or the little springs from clicky-pens that is being tipped slowly allowing the contents to roll around. It's, for want of a better adjective, a wet sound like metallic rain on a sheet of paper. Seems to increase proportional to throttle. Am I getting pre-ignition after all? Shall I back off the advance? Many thanks, Andrew
yep that does sound like pre-ignition to me, is the distributor definitly a kjet version? whats the part number on it
Hi Jonny, Dizzy P/N is 026905205AK Replaced, with your help, after this thread discussion. https://clubgti.com/forums/index.php?threads/in-a-tizzy-over-a-dizzy.290368/ Shall I dial things back to 6 degrees again? Many thanks, Andrew
yep thats fine then. pop the plugs out and have a look at them, also shine a torch into the bores see if they look heavily coked up. dial it back a bit also see how you get on. with 99ron fuel though should have no trouble dialing it up to 8 though. another thought, how are you setting the advance, with an adjustable timing light?
Hi Jonny, My thoughts about timing were the same, with 99 in the tank I should be fairly safe even to 8 degrees. Advance was set up, vac line off and plugged. Carb chap who I took the car to (Tony) used an adjustable light since had had all the gear. Previously I had used a static light with a new mark down the gearbox hole. When Tony first looked at the timing he confirmed that I was bang on 6 degrees before he spun it round a bit more to 7.5 we ended up at for the session. He then made a new mark on the dizzy and said if I wanted to play with it then I always had a point to return to if I needed. I'll pop all the plugs out for inspection tomorrow and see If I can get some pictures from down the bores too. Andrew
that'll be fine then, the original carb flywheel diamond timing mark is set at 18 degrees you see so if you were using that it'll be waaaaaay advanced
Hi again, Took some photos of the plugs. This is after bypassing the swirl pot with a fuel filter and 2 short drives on local roads. There are also some (low quality) photos of each cylinder that I tried to take with a cheap USB scope. https://imgur.com/a/TvmrBnD Cheers, Andrew
plugs dont look too bad, the cylinders dont seem all that coked up either so seems alright. though they look a bit on the clean side if anything in some of the pics, possible coolant leak into the bore? are all 4 the same or is 1 or 2 very clean vs the rest? though if it was gasket you would see a lot of white smoke out the back usually, cant really miss it when that happens from personal experience not sure if i can see damage from possible pinking or if its just carbon deposits
Hi Jonny, Thanks for the feedback. There is a bit of white smoke in the mornings. With it being so cold out this time of year I hadn't worried too much about it (thinking it was more steam than smoke). There is a slow coolant loss but I'd put that down to a small dribble from the top most radiator filler hose from the coolant bottle. I may have to contemplate a head gasket change just to be on the safe side. I guess I can run that by the garage mechanics tomorrow when they look at the control arm bushes. So if the plugs look ok and deliver a good spark, the fuel supply seems good enough (with the bypass), there's no air leaks around the carb, jets are clean, the timing is decent; where does that leave me regarding my acceleration hesitation? I think the only thing I need to do is find a restrictor for the return line and/or replace the swirl pot. I had a look on ETKA and couldn't see one listed. Were they only fitted to certain years/models? Will running straight past the swirl pot with the spare filter run the risk of over fuelling long term? Many thanks, Andrew
I wouldnt rush to HG tbh, if the hoses are over pressurised and its only a bit of smoke first thing I'd not be worried at the moment. maybe check next day after a good hard run when engines up to full temp sometimes you can spot a bit of coolant pooling in the cylinder if you have a small leak. the restrictor is part of the swirl pot, it should be fitted into the return fitting. sometimes they get dislodged and when the fuel lines are replaced they go missing, the 2e2 carbs dont seem to be that bothered it affects the webers more the accellerator pump is worth a check next, and a general go over on the carb make sure its got the right jets etc
Cool. I won't panic too much then I'll order a new swirl just to be on the safe side. Can confirm jets are what they should be. Pulled them all out and the numbers match the documentation for a 1.8 (checked your weber PDF) I assume I can get the accelerator pump off with having to remove the whole carb so I'll give that a check over. Andrew
Pump looks fine to me. As I expected given its newness. https://imgur.com/a/q7YG8Xu It seems to flow petrol in the correct manner too. Side note. While I was under the bonnet. I did see what looked to be signs of the dreaded mayonnaise in places I'd rather it wasn't. (Around the breather that goes into the air filter assembly, a spot on the carb and a white spot or two under the oil filler cap). Defo gonna get the garage opinion on the HG tomorrow now So if the fuel flows (assuming at the correct rate) do you have any other ideas on what to try next? Many thanks once again. Andrew
yep all looks good. bit of mayo in the top end 9 times out of 10 means you just havent driven it enough, if its on the dipstick then you start to worry. done a HG on a car which had actually gone into the coolant and oilways and the head was completly full of the stuff so you do know about it when that happens not a lot left then, hopefully just needs a tweak of the mixture
Thanks Jonny. The place where I took the car to get the suspension knocking sorted had a quick look at the oil and concurred that it was absolutely fine. Back to the carb. Shall I start with trying it a bit richer? I will of course be recording where every screw is set right now so that I can return it should the driveability get worse. Do you think pursuing a place with a rolling road sis a good bet? I almost feel like splashing out for an O2 sensor so I know what is going on while I'm driving. Andrew.
ideally get some equipment on to measure the CO whle you fine tune it, my 16v troubleshooting guide has a section on doing it by ear taken from one of the very early tuneup guides posted on here back in the day by an old member from another old member. Knowledge passed down from the generations https://clubgti.com/forums/index.ph...air-and-tune-your-mk2-corrado-1-8-16v.195423/ rolling road or live tuning on the road is always going to get you the very best out of it, the jetting can then be fine tuned to suit all situations. with all your modifications you'll probably find the base jetting isnt quite right. though saying that way back in the day I put a cam and kjet dizzy in a mates 1.8 with weber carb, used a snapped ruler to mark 6 degrees on his flywheel then dialed it in with around 8 degrees and it flew
Hey Jonny. Thanks for the link. I had a good read. So this morning, after fitting a new air filter I thought I'd have another stab at the car. I'd given it a good drive and pulled plug No1 just to see if it looked any better than before. I think it looks about bang on. https://imgur.com/a/tjafEqk Got it warmed up, still feeling that hesitation, and had a buckaroo moment at a roundabout as it lurched away in first. I pulled over and had a play with the carb. Tried giving it a little richer mix and noticed that it was idling around 950 so dripped it down just a little too. Felt a lot better on the quick sprint up the parkway and during the 30mph zones I got the feeling it responded much better in 4th and 5th than it ever has done. Hoping that's for me almost there for now. Might give it a run to work tomorrow and see how the plugs look after I get there. Andrew
