Running rough and rich on Pierburg 2E2

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Chazwozza
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Running rough and rich on Pierburg 2E2

Postby Chazwozza » Tue Sep 19, 2017 9:00 pm

Just a quick note, I'm not swapping for a Weber. You might think that is the best thing to do, fine, but Pierburgs can work and I'm trying to get mine too.

So I gave my car to a local classic car mechanic (non-specialist) to do a cam-belt change on my Scirocco, as it was a bit much for me to do at the side of the road while I don't have a garage just now. I asked them to do a coolant change while they were at it.

They then phone me a couple of days later to ask 'was the car was struggling to idle before?'.

Up until now, my car has run pretty much perfectly. Perhaps a touch of overrun on a hot day, but that's about it.

By the time I get there, they've tried their hardest, but they just can't figure out the thing, it's just about idling, but revs constantly moving around +/- 150 rpm, and idle that was a tad too low on warm-up (~1000rpm) and far too high at temperature (about 1500rpm).

I took the car home, can't figure out what's wrong myself, so I took the carb off and replaced all the vacuum lines and gaskets. I refitted everything carefully, autochoke lined up with its marks etc, but its pretty much unchanged. I've watched the carb as it warms up and the choke slowly closes, so I'm sure the autochoke is operational.

It's also clearly running rich, you can tell from the smell, it's literally spitting it out the exhaust, and fuel economy is down at least a third.

Does anyone who has cracked the pierburg have an inkling to what this could be?

TL:DR It's running rich and revs are jumping around, idle not quite right either, what could this be.

...I haven't even considered it's not the carb, but open to suggestions there too, but I can't see what would have triggered such a dramatic change



Mwstakyle
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Re: Running rough and rich on Pierburg 2E2

Postby Mwstakyle » Tue Sep 19, 2017 9:36 pm

Where are you located mate? Failing that I'll post a more detailed reply :)



Chazwozza
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Re: Running rough and rich on Pierburg 2E2

Postby Chazwozza » Wed Sep 20, 2017 12:02 am

Cambridge - which is an arse of a place to get to from pretty much anywhere :/



mark1gls
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Re: Running rough and rich on Pierburg 2E2

Postby mark1gls » Wed Sep 20, 2017 4:05 pm

It might be the cam belt is a tooth out, perhaps the old cam belt was out and someone adjusted the timing etc to get it to run and the garage has put it right, or the garage has put the new belt on wrong and it's a tooth out.
The car will sort of run with the cam belt out by 1 tooth but not very well as the spark is not happening at the right time.

Air lock in coolant system?

These are the 1st things I would look at as they was the last things done to the car before it went wrong.


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
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Chazwozza
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Location: Oxford

Re: Running rough and rich on Pierburg 2E2

Postby Chazwozza » Wed Sep 20, 2017 9:07 pm

Pretty sure it's not an air lock, but the cam belt positioning is interesting.

Would that not cause power loss though? It's not really down on power.

Afraid I've not really done work with cams before, so my knowledge gets a bit spotty here. I'd just take off the cover and check the marks right? The cambelt that was replaced was the original I think, as the car has only done 65k. So unless someone changed it due to age (I'll check the history, but it isn't complete), it was installed by the factory and I doubt they'd get it wrong.

Cheers



mark1gls
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Re: Running rough and rich on Pierburg 2E2

Postby mark1gls » Wed Sep 20, 2017 10:01 pm

Cam belts should be 60,000 miles or 6 years so I would hope someone has replaced it before if you you have been lucky it's not snapped if it's was 20 odd years old!

It's a pain photo bucket is still not working as I've lots of pictures of the timing marks etc as when I had my engine out I took pics.
If you PM me you email address I can send some pictures or you may be able to google timing marks, Mk1 Golfs are the same.
What year is your car as timing marks did Move for later cars.

This is what's on my 1978 Mk1 scirocco and 1988 Mk1 golf Gti cabriolet.

Remove the covers, you may need to remove the alternator belt to get the top metal cover off, remove the dissy cap and you will see a little line on the edge of the dissy which you line up the rotor arm so it's on the line and pointing No1 cylinder HT lead contact, then look at the camshaft cog and it should have a dimple on the inner edge of the cog and that lines up with the top edge of the head, there should be an arrow on the lower plastic cover which you then line up the bottom cog (crank cog which the alternator belt fits to) on the cog there is a line on the edge which should line up.

It may not be the cam belt being out as you said no lack of power unless the garage fiddled with the timing to try and get it running better, Do you know if they adjusted the timing?


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
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mark1gls
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Re: Running rough and rich on Pierburg 2E2

Postby mark1gls » Wed Sep 20, 2017 10:08 pm

Can you see the pictures in one of my older posts on Mk1 golf forum?

https://vwgolfmk1.org.uk/forum/index.ph ... s-mk1-golf


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
Mk1 88 Golf GTi cabriolet 1.8 DX. Daily drive.
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Chazwozza
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Re: Running rough and rich on Pierburg 2E2

Postby Chazwozza » Fri Sep 22, 2017 1:17 pm

Ah, yes, one would hope it had been changed then!

I can see the photos though yep, don't fully understand the whole thread to be honest, but with the pictures plus what you've just posted, I've got an idea how to check it. Thanks.

It's a 1988 car, so would presumably be the same as your cabrio?

I'll follow your instructions this weekend. I'm increasingly thinking this might be it,not the carb, in which case I'll be pretty annoyed with the garage as they weren't cheap.

Cheers



mark1gls
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Re: Running rough and rich on Pierburg 2E2

Postby mark1gls » Fri Sep 22, 2017 6:44 pm

Yes yours should have the same timing marks as my cabriolet.
Hope you do get to the bottom of this problem.

You can see the dissy timing mark and where the rotor arm should point about 1/2 down this thread.

https://vwgolfmk1.org.uk/forum/index.ph ... ket-change


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
Mk1 88 Golf GTi cabriolet 1.8 DX. Daily drive.
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Chazwozza
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Location: Oxford

Re: Running rough and rich on Pierburg 2E2

Postby Chazwozza » Thu Sep 28, 2017 9:41 pm

Sorry, took me a few days to try all this out. Thanks so much though mark1gls, followed your instructions and indeed looks like the last cambelt was fitted lazily and the timing adjusted to make up for it. I lined up all the cambelt marks etc and adjusted the position of the dizzy, ran almost perfectly instantly.

Again, thanks very much.

Remaining issue I have is that the carb has been adjusted by both the garage that did the belt and myself for what was an out of time engine. As you can jnagine, it's a bit out of wack now, with revs too low at cold, too high when warm and fuel consumption still too high, about 25mpg.

My thought is to wind down the idle screw, (for the too high idle at warm) and check the autochoke is in the right position (for low revs at cold) . I'd hope the two of those will bring the fuel consumption down.



mark1gls
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Re: Running rough and rich on Pierburg 2E2

Postby mark1gls » Thu Sep 28, 2017 10:44 pm

Good to hear is sort of running better now.
You still might need to tweak to timing to get it spot on. Mark where it is now so you can but it back if it all goes pair shaped, I set mine up by advancing the timing (turn dissy clockwise) till then engine "pinks" under load (window open, 2nd or 3rd gear and revs about 2000 rpm then slowly push the accelerator to the floor and listen out for pinking noise) if you hear the noise retard the timing (turn the dissy anti-clockwise).
You need a quite road and ideally going up a hill helps, you need to keep stoping at the side of the road and turning the dissy and you then need to adjust the idle speed. Beacarful of the fan coming on as you work near that area.

Timing gun is easier and I think you need to disconnect the vacuum advance connected to the dissy and plug the end but not 100% sure as I don't have a timing gun. :-D

I would find another garage to use if they did not spot the timing marks were out when changing the cam belt as they should of checked....


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Chazwozza
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Re: Running rough and rich on Pierburg 2E2

Postby Chazwozza » Tue Nov 21, 2017 2:58 pm

Sorry for the late update here, it took me a while to get a timing gun and give this a proper stab.

I first tried doing the timing by ear, things got a bit better, but it was still spitting fuel out the back, with high fuel consumption.

I then got my timing gun, the timing I had done by ear seemed a bit retarded when I used this, so I put it forward a bit. I had to wind the idle screw up to compensate for a drop in revs, and while there seems to be less fuel out in the exhaust, the car is still using too much fuel and is now running a bit hotter (nothing the fan can't cope with) leading to overrunning when the car is turned off. There's also substantial flat spots in the rev range too. This would suggest it was too advanced (I think, may have got that wrong way around, I'm new to this) but it is exactly on the marks, which doesn't make much sense.

I must be doing something wrong here, but I can't think what. I'm setting it when up to temperature, the car has a level idle. When you apply throttle, the timing marks briefly come unaligned, but I assume that's normal? The upper marks on the camshaft all align too, I thought that might be a tooth off or something, but it seems correct. I haven't disconnected the vacuum advance, but that completely kills the engine. My haynes manual says that's only necessary on some cars, but I can't determine whether my cars is one of them from what it gives, I don't know if that could cause this?

Are there any mistakes or errors in what I've just described? Or any ideas more generally? I'm very confident that the timing is the issue here, not the carb or anything else, but 'technically' the timing seems perfect now to me, but it clearly isn't.

Cheers



mark1gls
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Re: Running rough and rich on Pierburg 2E2

Postby mark1gls » Wed Nov 22, 2017 10:23 am

I think but not 100% sure you need to remove the vacuum advance pipe from the dissy and plug the hole on the end of the plastic/rubber pipe, then set your timing.
Might be worth giving this a try?
I does sound as if the timing is still a little out, is there much play in the dissy shaft?


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
Mk1 88 Golf GTi cabriolet 1.8 DX. Daily drive.
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Chazwozza
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Re: Running rough and rich on Pierburg 2E2

Postby Chazwozza » Wed Nov 22, 2017 3:02 pm

You again seem to have come up trumps mark1gls, blocked the vacuum input on the dizzy, set the timing and instantly the flat spots are gone and there's no fuel coming out the rear either.

The proof will be in whether I get more than 250 miles from the next tank of fuel, but thanks in advance, I thought I was doing something small but significant wrong.



mark1gls
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Re: Running rough and rich on Pierburg 2E2

Postby mark1gls » Wed Nov 22, 2017 4:22 pm

No problem, glad I can help.

Mark where the dissy is now, so if you want to tweek it a little you can always put it back, you can sometimes advance the timing (turn clockwise) a little bit more (I do mean a little bit) from where it's set with the gun to get a little bit more out of the engine. See how it runs etc and let us know who you get on.

250 miles a tank if you have the larger tank 55l (space saver wheel) is not good.
Try not the drain the tank to much as you don't want the crud etc from the tank in the fuel lines, I fill/top mine up when the needle is about at 1/4 tank.


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