Mk3 GTI 8v - Rough running

[scorchi0]

Hi All,
I've not had my car very long, it's a 1996 Mk3 Golf GTI 8V (AGG engine with Simos injection) but it's got a little bug that's annoying me.
When idling the car seems to miss, but not a really rough miss like an ignition problem. It seems more like a mixture issue...It happens not only at idle but when the engine is running at steady revs and not under load. So I could be coasting along at 30mph in third and holding the car at that speed and it chugs like it is missing. The car accelerates super smoothly and deceleration is fine too.
I had already changed the plugs and leads which made no difference anyway and the car has just been in for an 80,000mi service where in addition to cambelt and filters I changed the coolant temp sensor and oil breather tube with no effect on my problem.
I've checked all the other intake plumbing which seems to be in good condition and sealing well.
Has anyone else had a similar problem? I'm thinking i'll go along the way ov changing the Lambda sensor and then the air flow meter if it comes to it...
Any input is appreciated, thanks
Trent

[andrew.butler57]

hi there, i to have this exact similar problem although mine is getting to the stage of nearly cutting out ! i've replaced and the usual stuff and the list is still growing! after looking at it today i've found that when it starts playing up the engine load signal goes sky hi! also found active charcoal filter solenoid valve stops working too, if you have any luck with yours please let us all know there are so many running faults with these gti's it's un real!!!

[andrew.butler57]

oh by the way i've replaced temp sender, lambda probe, engine speed sensor, fuel filter, oil change, air mass meter and have tried ecu and throttle body, nothing makes a difference! it also seems the fault is tempreture related!!!

[Crasher]

These ADY and AGG engines are very sensitive to HT ignition components, that is cap, rotor, leads and plugs and by sensitive I mean down to the exact make used. If you fit plugs, they need to be NGK BUR 6ET or Beru 14 GH-7 DTUR and leads must be genuine or another very high quality make. The cap and rotor must be Bosch or Beru. The coils are also very prone to playing up subtly like this. The other problem is if you have an ADY engine, they are prone to running problems and VW brought out a repair kit for this which consisted of a special ECU and the AGG camshaft.

[Desertfish]

Hi Guys:

Bought myself a 1995 MK-III 2.0 8v GTI a few days ago and it seems the previous owners have been very generous. Apart from the full service and MOT history, they also provided me with the invoices of all the work carried out on the car since 2002.

Going trough the paperwork, I found that mine had two similar problems in the past:

A few years ago, the engine was cutting out when under high load - especially when the radiator fan was cutting in. That problem was traced to an engine relay fault and was fixed by replacing it with “a modified unit as recommended by VW”. At least that’s how it appears on the invoice.

Two years later, a similar problem happened where the engine was cutting out when running idle or under low steady revs. That one was fixed by cleaning out the throttle body although the invoice stated that if the problem should occur again the throttle body would need to be replaced.

Both were carried out by official VW dealerships. The first one was a £140 job, the second one £100.

Hope this helps.