Mysterious misfire

[Klaus]

Hi - I'm a new member
Early 1999 VW Golf Wolfsburg edition
Chassis No. 3VWJB1H9XM221733
Engine No. ABA596697
Mileage: 43,500 (69,000 km)
I have a mysterious problem for which I would appreciate receiving your advice.
Engine starts easily, idles a bit rough at about 900 rpm, reaches and maintains normal temperature, and displays no engine warning signs.
BUT, No. 1 plug (near cam wheel) is discoloured and wet (gas, not oil) and when I remove the lead to No. 1, there is no change in the idle, implying that No. 1 is not firing.
A few facts: No. 1 plug has fat, blue spark. No. 1 injector impedance is about 14 Ohm and voltage to injector a bit over 8 V. Compression in No. 1 and No. 4 about 120 psi. Gas mileage (hold on to your hat) is 20 L/100 km (I drive mostly in dense Manila traffic).
My attempts.
1. Installed new plugs, distributor cap, rotor, and air filter – no change.
2. Removed cylinder head – cylinders appeared normal, valves and seats were slightly pitted.
3. Lapped valves and installed new valve seals.
4. Reinstalled head according to manual (new gaskets and head bolts).
5. Engine started easily, idled a bit rough at about 900 rpm, reached and maintained normal temperature, and displayed no engine warning signs.
6. No. 1 plug (near cam wheel) is discoloured and wet (gas, not oil).
7. When I changed No. 4 plug and injector to No. 1 position, there was no change.
I’m stuck !
Will appreciate and follow up any hints.

[WhiteturboGolf]

Ok trying to work out what car this is mk3 or mk4!
Your VIN doesnt sound right a Golf will start off with WVWZZZ then 1H for Golf 3 or 1J for Golf 4
The X suggests a 1999 model but Golf 3 finished in 1998, June 1998 was the last one that was built.
ABA suggests its the 16V engine that came only in mk3 Golfs

Id suggest removing the fuel rail complete with injectors unplugging the injectors and checking to see if there is any leakage through the injectors
Also check your fuel pressure, maybe change the filter?

[Klaus]

Thanks for your thoughts.
It's a Mk3 alright and the ABA in my Mk3 is an 8V (counted them myself when lapping).

My info is that the 3 means it was built in Mexico (the car was imported fom California). Maybe that explains the other oddities about the chassis number.

Nothing I saw makes sense to me. And since the fuel filter and fuel pressure affect all injectors and only one plug is fouled - well, you see where that's going. I swapped injectors (No.4 for No.1) to see if that was the problem but that didn't change anything.
The thing runs, and not all that badly. But I'd prefer to run on 4 rather than 3, or 3-1/2.

[Tim]

does the car drive ok or does it sound like its running on 3 cylinders?
Is it possible that your cylinder 1 lead is leaking spark. Sometimes more apparent at higher revs but very difficult to see at idle?
You dont mention anything above about changing leads. It only takes one little crack in a lead and as you rev the car up the spark can jump across to anything else that is near by.

[Klaus]

Tim
I forgot to answer your questions:
1. The car drives ok, although a bit gutless for a small 2L machine.
2. It idles a bit rough and that led me to check...and find that removing No.1 lead made no difference. I'm really surprised that it runs as well as it does with apparently only 3 cylinders.

Just to reiterate: I did remove No.1 lead and obtained a fat blue spark grounding the lead against the motor. Is that inconsistent with your idea of intermittent grounding at higher revs?

[Bug_racer]

Are you sure you have the leads the right way around ?
Im guessing this is a 2.0l cross flow engine ?