Right here goes.... its going to be a long one but I'm desperate to get it sorted with my Jetta now being my daily its starting to become a nuisance I have a mk2 jetta with a 1.8 driver (GU) engine running a Pierburg carb (which i think may be jetted for a 1.6) I'll give you the whole story from start to finish.... Basically I managed to cook the engine a bit due to the flange on the front of the head coming loose and emptying the water, (as my temp gauge didn't work) I was unaware until it was too late. So I had the headgasket done, skimmed, all back together all seemed well but then the mechanic struggled to get it to idle properly... it was revving right up on idle upto 1000rpm at points, he also said the timing was out but the dizzy was stuck in place and he didnt want to break it getting out incase I didn't have another one so he did his best, but the only way he managed to stop it reving up on idle was by bending the arm on the left side of the carb as you look at ( i think the 3/4 unit pin pushes it out when cold?) It seemed to be ok, a temporary fix until I got hold of another dizzy I used it for about 2 weeks on and off without issues apart from the engine being a bit rattly under load (someone told me it was pinking as the timing was too advanced?) Anyway about a week ago the car started to have a few issues with stalling when warm... I could start it and drive it from cold and it was fine for say 10-15 minutes then it would start to stall every time i placed my foot on the clutch e.g pulling up to juctions etc it got really bad , and the pinking noise seems to get worse at the same time. Eventually I run out of luck and end up stalling and it will not start again! I turned the key but its almost as if the starter is stuck, or the battery is too flat to turn it over, but when i had a jump from another car it would start up but then just stall again as soon as i put my foot on the throttle.... So I got towed home and had a prod around the next day and ended up swapping the ignition control module over.... it started up straight away and drove fine for a day and then once again the problem when it warmed up happened again after a 15 minute drive it stalled when clutch was pressed and it wouldnt start again until i got a jump from another car... ( i though perhaps the battery was faulty but then when ever the car is cold you can turn it on and off as much as you like and it never seems to stuggle?) I am banging my head against a wall trying to figure out what could be causing it and can not find any specific topics with the same problem on here or other forums so....... ANY HELP WOULD BE MUCH APPRECIATED!!!!!
When you say it was revving right up on idle to 1000rpm at points, do you mean 2000, or 3000 perhaps? 1000 is only just above nominal warm idle speed? Have you got the temperature gauge working again yet? Also might be a good idea to implement coolant level sensing to help prevent future problems, a search in the electrical section should find some info. Anyway, I'm going to assume you did mean something like 3000rpm as the 'problem' revving, which would lead me straight to the belief that your ThermoTime Valve (TTV) isn't getting electrical power, which in turn causes the 3-point unit's actuator to stay at the 'fully out' starting position until engine bay heatsoak warms up the TTV passively. Your mechanic's bending of the bracket that this actuator pushes against was a poor solution, unfortunately. Need to restore power to TTV (might be a blown fuse if it's a CE1 car, if not a broken wire, or maybe just not plugged in?), then bend bracket back to how it was. With it still bent, once the TTV does passively warm up enough (and the recent mild weather will make that more likely), the 3-point actuator will withdraw to the normal 'mid' position for warm idle, which will no longer reach your bent bracket, so the primary throttle will close right off causing stalls. Need to check ignition timing and perhaps intermediate shaft timing too by the sound of it; latter then former. Here's a pic of a 3-point unit (on the left) and a TTV (on the right), in case you're not familiar with the terms:
hi pete... Sorry you are right I meant more like 2000rpm.... thanks for the info... I left my car with a vw specialist today and he managed to sort the main problem out straight away.... he called me and said he sorted the timing out pretty swiftly finding out that timing was a tooth out so that was why it was running so badly.... he also mentioned that 3 plugs on the carb didnt have any loom to plug into so was quite shocked how it was running as well as it is now.... i drove it home tonight anyway and it appears to have stopped the stalling issue... but i could still do with a weber to go on it as the pierburg is set up for a 1.6! and it can't be ideal! I will probably try and bend that arm back to its normal position just until I manage to get a weber to replace the pierburg. Thanks again for the advice, I'm just glad I can actually get about again... i didnt like walking to work!! haha cheers steve
If someone has hacked the loom about and left you nothing to power up the TTV with, there's no point in bending the arm back; you need to do both things, not just one, or you'll be no better off. Differences in jetting from 1.6 to 1.8 are fairly minor actually, I seem to remember coming up with a theory about why some of the fuel jets on the 1.6 set up are bigger than on the 1.8, about a million years ago. Can't be bothered to dredge it up as you sound intent on fitting a Weber. Best of luck with that.
I'd have thought that there's a chance that the cutting out problem is good old fashioned carb icing. Is standard airbox fitted, and the hot air duct from the manifold?
EZ_Pete thanks for all the info... I'm gradually picking up bits of knowledge as I go along, hopefully one day I will be able to detect my own problems! but until then its club gti members to the rescue! thanks for taking the time to help much appreciated p.s it appears to be running really well now without any plugs plugged in ?.... but saying that it has been quite mild so this cold spell of weather thats coming will put that to the test I expect! Mike_H Its running ok now... the airbox is standard but i am missing the funnel bit on the end, and yeah the pipe is still attached from the manifold
Have you got an earth running from the front of the carb to the cam cover? I've had this missing before and caused stalling at junctions, I had to keep the revs up with one foot and brake with the other.
The fact that it can idle OK without the electrical bits plugged in actually indicates another fault, which is helping to compensate for the lack of TTV and overrun/cutoff valve action. lol I would say, with 95% confidence, that your waxstat is also not doing its job quite as intended. This is a device on the front of the carb with coolant connections, and regulates the minimum idle speed during the first few minutes after a cold start. When they don't get a good enough supply of coolant, or they lose some of their wax, they then either take longer to hand over control of the idle to the 3-point unit, or never do so at all. As your waxstat is holding the primary throttle slightly open (even after it should have stopped having any influence), your engine will keep running (now the timing is sorted) even though the electrical bits that normally enable the correct operation of the 3-point unit are not powered. One thing you may notice, is that the engine doesn't switch off very cleanly, and may tend to run on sometimes. Fuel economy is likely to be poor as well.
