Golf Mk4 TDI Occasional Misfire

[Graham Mason]

I own a VW Mk4 1.9TDi GT Diesel Golf 03 plate, bought from new (My first ever new car). It has been serviced at a VW dealer from new.
In the last few weeks I have had a problem when driving to work, a journey of 11miles. After about 8 miles on some mornings the engine starts to misfire causing a juddering and the ESP light to come on. When I switch the engine off and the on again the ESP light is reset and the problem goes away. The problem has never occured on the journey home which is stange.
So far I have spent £200 trying to rectify this fault - £110 to garage No.1 (not VW) who diagosed a faulty sensor, and another £90 to garage No.2 (A VW dealer) who found the turbo disconnected? Neither has cured the problem. I have now been to the same VW dealer and have been quoted £790 to replace a wiring loom feeding the injectors.

After visiting this forum I found a number of postings about similar problems. Also, similar problems appear to have occured on earlier versions of the Golf. Does anybody know if this is an engine design fault which VW has been aware of and keeping quiet about? Also, what is it about a wiring loom that can cause this type of problem, after all is'nt a wiring loom just a load of wires bundled together?

Any experiences and/or info welcome.

[Tallulah]

Get someone to check the pressure in your cylinders this sounds like a similar problem that i have had but by continueing to drive the car it can make more damage to the engine - good luck

[dat90]

Hi, I have recently had a very occasional misfire.....progress to a more frequent misfire, but only when accelerating....not so much hard...but 'assertively' when not much load in the car, to soft accelerating with good load in car. Initially was puzzled by this, but read on forums that it could be the wiring loom in the head.....apparently a comon problem.
So, was about to do a routine service, but orderred a loom anyway. Loom cost about £42, however since changing oil, the misfire has never returned. As the loom is in the head, it may get oil in it, so could oil quality have an effect? Are you on an extended service/oil change schedule(as I was)? I don't like the idea of oil lasting that long anyway, so am going to stick with shorter changes. Try changing oil and see!
The misfire, when it shows, is only momentary, as if the whole engine cuts dead then continues.....unlike a misfire where one cylinder is dead while the engine is running.

Hope this is of help.

[Graham Mason]

Well, you might be right about the oil as I too am on the extended service interval. I hope it wasn't as simple as this as I have just spent £750 on a new loom and injector on No.1 cylinder at VW garage. This did cure the problem though. It appears their diagnostic check does not isolate the problem exactly. I think they change everything that might cause the problem to be on the safe side (and charge heavily for it!!). I, like you, was thinking of changing to the normal service periods as the car is now 5 years old. My 'service required' warning light came recently and when I took it into the VW garage they reset it - they said that the service was not due?? Now I am not sure when the warning will come on again? I think its something to do with the oil quality but am not sure

Thanks for communication.

[dat90]

Hi, I have been running a couple of weeks on new oil and the misfire has never appeared. Before I changed oil it would misfire nearly every day. What mileage is yours?...I've done 54k.
The oil differences are mainly if you use 'standard' oil then you have to change it at short intervals. There is a 'variable schedule' which allows the oil change to stretch to 20k, but must use long life oil (there are a variety of VW spec numbers which I wont go into).
I now use Millers XFE-PD as I know from experience that their oil is good, it is made specifically for the PD engine, and it is approved by VW.
I have VagCom and will soon look to see what shows up, but as the problem has gone for now, it is not so urgent. I still have the new injector loom standing by.....which if needed will fit myself...checking that the terminals are crimped tight as I fit it...as that could be a possible weakness.
When the misfire started to show...it was just at the start of the new year...cold and damp. Dampness could have been a problem at earth connections, or a problemat the loom connector, however an oil change was due so done that and had a look over everything for signs of poor connections....nothing obvious, and strangely the misfire has gone. It is a strange one though, as why should it show momentarily when accelerating firmly.....I thought that was like a slack connection, showing up when the torque of accelerating maybe flexed part of the wiring just enough to open circuit.
Might never know for sure. Intermittent things are always a devil to trace for certain.
Will keep an eye on it with interest!!

[Graham Mason]

Thanks for the info. The VW garage has fixed the fault by changing the loom and injector (£790!!!). Don't really know what the exact fault was but oil in the loom sounds like a possiblity. I did previously put petrol into tank instead of deisel and then run it as I didn't realise 'till it was too late. This was a year ago. Maybe that caused a problem with the injector?