Hi,

 

I've had this issue for a while, and I've been active on the polo group on facebook whilst trying to figure out this issue. I'll provide a timeline for my issue.

 

1. I changed timing belt, car started and I had no engine jerk. Car has always been difficult to start and nothing changed after changing the timing belt.

2. After around 2-3000km and 2 months, the car dies on the highway in the middle of a tunnel. After a couple of days with fiddling with vacuum lines, spark plugs, fuel and other fault seeking methods, I discovered that the ECU (multipoint Jetronic) had a blown circuit on the ground which stopped the injectors from opening. Added some solder and engine started. However, the engine now had weird idle and was uncomfortable to drive. Replaced ECU with a new unit from Ebay, no difference in behaviour. 

3. I have changed sparkplugs,  distribitor unit (complete) with hall sensor, distrubitor dizzy, distribitor cap, leads and coil. I also changed middle part of exhaust and all vacuum lines with new VW oem Ø3.5mm ones. 

4. A post on facebook told me to check the timing, which I did. Haynes told me that the timing mark and timing light should overlap, but I am unable to actually change the settings enough to get the light to hit the edge of the timing mark indicator on the engine. I'll add some figures below. The Yellow line is where I am able to adjust the timing to be maximum, the green is where haynes recommends me to be. Did I buy the wrong distributor? It had a different letter in the end of the Part Number. 

 

If it is not the timing, which other things can cause engine jerk? It is really intermittent and only on cyl 2 and 4 which I checked with the timing light. It is as if it "skips" every 2-4th of the sparks.

 

Anything else I can check? 

 

Thanks in advance.

 

Yellow: Max adjusment I get, distribitor location in next figure. Green is where haynes tells me to be.

 

Figure: Unable to advance timing further.

Figure: Haynes recommendation of base timing setting. 

Figure: The setting above lets me hit the setting recommended by Haynes. 

 

 

 

 

is that a generic fits all polo ebay distributor?  some will fit and look the same but dont work the same

 

it would be good to see your timing belt marks , if the cam is a couple of teeth out this would happen

The item number was:

 

Distributor, ignition VW Golf Polo 030905237EX 0237021074. My original had PN: 030905058C

 

 

Not the identical,but looked identical and fires up with no problem. Hall sensor contact fits perfectly.

 

as for the timing:

 

 

the lower setting is set at the white scribbled line.

 

 

 

If you pull the vac tube off the UFO capsule and plug it does that move the mark nearer to to Z?

 

What engine code?

 

Surging acceleration and hard starting can be lean condition (on carbs anyway).

I’m checking the timing with the vacuum UFO disconnected and plugged, but is fairly off no matter what. It’s been a while, I’ll double check.

 

I believe it is the NZ or F, it’s a 1.3 with jetronic. At least all 4 injectors fires simultaneously. 1991 mod, 55ps.

 

 

Hard to start can be timing out too, of course.

 

New rotor arm?

Are leads 2 and 4 properly connected?

Fully home in dizzy and on plug?

Always been removed pulling the end boots not the cable? 

 

You could also start it in twilight and look for tracking to earth, plasma glow.

Another idea. Cam timing pulley removed and put back on back-to-front?

No picture looks like the proper mark.

Edited 20 December, 20214 yr by dvderlm

If it is 3F, ignition is set at 2000 to 2500rpm with vacuum tubes connected including the engine breather from block to intake (but 3F does not have a UFO capsule in dizzy, so I'm not sure).

 

AAU has no vac tube.

 

AAV after 1990 is mono-motronic. Single injector.

 

NZ is Digijet. With Supertorque cambelt teeth.

 

 

I’ll try looking at my timing tomorrow.

 

Then I believe it is NZ. Are the supertorque campbelt teeth easy to identify? Where should I be when taking the timing settings? I have no RPM gauge or RPM counter available at the moment.

 

i’ll add an image of my ecu.

 

 

 

 

 

 

Digijet ECU confirms NZ engine.

Supertorque teeth are pointy. Older belts are square bars evenly spaced.

 

Mechanical timing looks good if rotor arm pointing at right place for number one cylinder when at TDC and bottom pulley at the 0 point.

 

Gap between 0 and Z is 5 degrees. The left hand end of timing metal indicators is not as pointy as on mine.

 

From the green line it looks like running 20+ degrees advanced, so

I wonder if the vac advance mechanism is giving advance when it should not.

If you can apply vacuum to the canister (eg a mityvac) does it move the illuminated timing mark when idle?

If not the new dizzy is faulty.

 

Unless the dizzy is fitted to the wrong slots rotated by 160 or 200 degrees and leads moved to give 1342 again _ not sure that is even a possible mistake.

Edited 21 December, 20214 yr by dvderlm

Okay so I went out in my garage today to see if I could check my timing. I didn't check the timing directly on the cam/crank marks as I have already checked it a couple of times earlier.

 

However, I removed the dizzy assy and went ahead and filed away on the slots in which the dizzy is attached to the engine so that I can further reduce the advancement on the engine. I removed about 6-7mm of material and can now get it almost to hit the point in where i should adjust the timing to. I did this as an experiment really, just in case I got a dizzy that was a little bit off. If I give the engine some gas, I can clearly see the vacuum UFO advancing the timing, so I believe it is in working order. I can try using my oil puller to give it som vacuum later.  Car now sounds a little bit calmer than before.

 

 

Further, I tested the timing light on all the leads, including the one inbetween the Coil and the distributor.

 

During timing adjustment, I had the inductor coil from the timing light placed on the red lead (Cyl 1) in the figure below. I can clearly see that the timing light output on cylinder 1 and cylinder 4 does not fire as smoothly as when I am having the inductor coil on cylinder 2 and 3. It is almost as if the car "skips" firing now and then.

 

I also tested the timing light on the lead that goes directly from the coil to the distributor, and I could see that the light disappeared sometimes there as well. Shouldn't this light be almost constant? It makes me believe that the contact between the dizzy and the distributor cap is compromised in some way, on the background of the fact that I am "losing" light in my timing light, intermittently. If no electricity passes through the lead =/= light.

 

The dizzy and the cap that I have was included in the dissy assembly I got. My dizzy has the "small" alignment pin that comes out of the distributor. Is there a special kind that is better than others?

 

The dizzy cap is keyed and can be put on the distributor upside-down so it wobbles giving poor contact from rotor arm to sparkplug lead contact inside the dizzy.

 

I'd expect 4  flashes per rotation from king lead.

And equal even spaced flashes at slower rate from any lead, unless engine speed is wandering.

There are two type of socket on distributor caps.

 

Just a hole (7 or 8mm?)  old, or

a hole with a central pin, new.

 

The plug lead ends should match or there is possibility of poor contact.

Usually you can put new style leads in old dizzy caps. Not sure about old leads in new caps without some surgery.

 

Edited 21 December, 20214 yr by dvderlm