Hi all,
So after adjusting everything possible on my Golf Driver MK2 1600 cc cab,
I got a new problem,...
When stone cold in the morning, turn in on, rpm goes to 1100 for a few minutes, then suddently goes to 1400 rpm and stays like this what ever i do for 20 minutes and then goes down gradually back to 900 rpm +-.
For the rest of the day, every time i start it, it's bang on at +- 900 rpm.
Next day the hole thing starts again !
I have no clue what's wrong ! thanks for your help :)
Philip.
Hi if you stop the engine once it is warm does it idle normally?
yes it does after 20 minutes,...from cold, sorry
Hi I obviously did not word that too well what i meant was as soon as the engine is warm enough not to need the choke if you stop the engine and restart does it run normally. The engine should be up to temp long before 20 mins.
Hi, may be i didn't explain correcty too lol. So when stone cold, start the car, rpm goes to 1100 ( auto choke i guess,.. ), i start driving and after 1 minute, the rpm goes to +- 1400. After driving for about 15 minutes when the temp is in middle and car hot enaugh, it starts to slowly drop back to normal idle within +- 5 min. To answer your question, yes, at that point if i turn off the car and resart it immedialty it idles perfect at 900 rpm and for the rest of the day until stone cold again,... And yes it should be warm enaugh long before all this,...I am going today to do another test as i might have a theory, not sure. I will drive the car for a few miles, it will idle at +- 1400 still, park, turn it off for 20 minutes and see if it goes back to 1400 rpm immediatly or if it will idle fine. I will let you know,...thank you.
Ah the joys of the pierburg. A few things to get us started. The idle is not controlled by the choke. Its controlled by the three point unit, and the waxstat. When you first fire it up it should briefly reach the initial idle speed, about 1400, for a 10 secconds or so. This is controlled by the thermo time value that adjusts the vacuum and causes the three point unit to stick out as far as it will go, which I'll call position 1, then the three point unit should retract to its middle position (position 2), at which point there will be a gap between the throttle arm and the three point unit as the waxstat will keep the idle higher. As the waxstat warms up (check you are getting hot coolant flowing to it), it will push a pin which will cause the throttle arm to move back towards the three point unit. When hot there should technically be no gap between the throttle arm and the three point unit. Mine always had a gap, but I never got around the adjusting the three point unit.
The fact that it eventually drops to 900 when hot suggests that everything is working but the waxstat is slow to warm up. To be honest, they are always a little on the slow side to warm up, but I would say 5-10 minutes is probably like normal. Start the car on the drive cold and watch the carb go through the cycle. Check to make sure coolant is flowing through the small hoses to the waxstat.
Position 3 of the three point unit is when its fully retracted, which happens when the you turn the engine off causing a solenoid to close/open, and the total vacuum increases to the maximum causing the three point unit to pull back. This causes the throttle flap to shut and the engine cuts off.
One last thing. The choke only controls the mixture. In my experience they tend to give far too much choke when its fired up form cold. I backed mine off a bit, cause it ran too rich when I first fired it up, causing it to flood a bit (lower revs). The choke is controlled electronically and via the coolant. When its cold make sure the choke is getting 12volts. If not it will be relying on the coolant to warm up and that is waaaaaaay too slow. Its controlled by a thermoswitch on the top hose to the radiator. The video explains.
I did a video a while ago that explains all the parts of the carb, that you might find helpful.
https://www.youtube.com/watch?v=taTBdkrQouI&t=16s
Thank you very much for your very very helpful comments and video. I will study this when i have a bit more time. I see you got the same golf as mine and even the color tornado red :). I have done my test so basicly instead of driving for 20 minutes for the rpm's to drop back to normal, i started the car, ran it 10 minutes as it does at 1400 rpm+-, turned it off for 30 minutes and started it again and the idle was perfect ! So, correct me if i'm wrong but seems to me the 3 point unit is just very slow to retract ? or is it is the waxstat thing with the needle that is frozen ? I did change it 10 years ago to a metal one instead of plastic,..Food for thaughts,...Thanks again. Phil.
Thank you very much for your very very helpful comments and video. I will study this when i have a bit more time. I see you got the same golf as mine and even the color tornado red :). I have done my test so basicly instead of driving for 20 minutes for the rpm's to drop back to normal, i started the car, ran it 10 minutes as it does at 1400 rpm+-, turned it off for 30 minutes and started it again and the idle was perfect ! So, correct me if i'm wrong but seems to me the 3 point unit is just very slow to retract ? or is it is the waxstat thing with the needle that is frozen ? I did change it 10 years ago to a metal one instead of plastic,..Food for thaughts,...Thanks again. Phil.
My best guess, without seeing it, is that the waxstat is slow to react. So when you switch off the heat from the engine rises up to the carb and causes the wax to melt and push the idle down. Why its slow to react is a good question (lack of coolant flow perhaps). Have a watch of my DIY video first. I describe how the warm up procedure works, and what and how the various parts of the carb operate together. Once you understand the process you'll be able to understand what is going wrong. In short, if the waxstat is to blame, there will be a gap between the throttle arm and the 3 point unit. If its the 3 point unit to blame, the throttle arm, once hot, will be touching the throttle arm.
There is a useful PDF of the pierburg manual, which shows the various vacuum hoses and what they connect to. There are also a few other older videos that explain how the vacuum system works, but the short version, is the thermo time value and the solenoid reduce and increase the amount of vacuum that the three point unit receives, to control the position of the 3 point unit. Any leaks in the hoses therefore mess up the position of the 3 point unit. I believe you can bypass the thermo time valve and solenoid and the three point unit will always sit in the middle position (hot engine), but of course that makes driving it cold a nuisance as it will stall.
Hi that is what I was trying to figure out whether the wax stat was the problem. Keekster64 you put it better than I did.
Whilst I remember, there is a rubber seal between the intake manifold and the cylinder head. When they get old they swell, and this can restrict the flow of coolant to the waxstat. Eventually they can break up and get stuck in the intake manifold and block it. To check make sure the hoses to the waxstat are increasing in temp at the same rate as the top radiator hose. If not you may have to remove the intake manifold. I did it recently and its deceptively tricky. You need the right tools to do it.
Thank you all for your help, while i study the video,...I will try to upload a video of the hole process so you can see how it goes as there is something about the 3 point unit that seems wrong,..will try to show,...I'll update as soon as possible.
Thanks again,
Phil.
Another test done, turn on the car, idles at 1000 rpm, drive 1 minute, shoots up to 1400 rpm, drive only 10 minutes, come home, still at 1400 rpm. Turn it off, start right away, back at 1400 rpm. Turned it off, waited 45 minutes, start again, idles perfect ! It must be the waxstat ! I'm looking to buy one again but they seem to be impossible to find now. I only found this website but it's out of stock and frankly expensive anyways as i did change it over 10 years ago and i wouldn't have spent that much i'm sure,....Any ideas where i could fetch one ? Thanks.
https://www.classic-vw.co.uk/pierburg-2e2--2e3-carb-wax-stat-026129243c-7716-p.asp
Another test done, turn on the car, idles at 1000 rpm, drive 1 minute, shoots up to 1400 rpm, drive only 10 minutes, come home, still at 1400 rpm. Turn it off, start right away, back at 1400 rpm. Turned it off, waited 45 minutes, start again, idles perfect ! It must be the waxstat ! I'm looking to buy one again but they seem to be impossible to find now. I only found this website but it's out of stock and frankly expensive anyways as i did change it over 10 years ago and i wouldn't have spent that much i'm sure,....Any ideas where i could fetch one ? Thanks.
https://www.classic-vw.co.uk/pierburg-2e2--2e3-carb-wax-stat-026129243c-7716-p.asp
I'm assuming you touched the coolant hoses to the waxstat to check they are getting hot, as you dont mention it? That aside, I would removed the waxstat, complete with its hoses (when its cold) and submerge it in a cup of boiling hot water. You should see the metal pin in the centre push out. This is supposed to reset it, ie, without spring pressure restraining it. If it leaks wax or coolant from around the pin, its knackered. If not, then refit it and see if it improves.
yes sorry i did test the coolant hoses and they are getting hot. I was just about to ask if it was worth it to take it out and do the boiling water test in the hope of a miracle or improvement,...lol. I will do this over the weekend as at the moment weather here south east not the best,...If i remember well, I only have to take the air filter housing off to get easy access ? thanks again, fingers crossed as this problem just suddently started 6 months ago.
and i forgot, i looked at the 3 point unit, there is no gap what so ever cold, or hot,...