Mystery Misfire

[bowline5]

I have a 2.4l V6 A4 with an occasional misfire under even gentle acceleration. Sometimes the engine warning light comes on, stays for a while and goes out again; sometimes it flashes as the misfire is happening then goes out. All the OBD scanner tells me is that there is a misfire on No1 cylinder. I've changed the plugs and the coil pack and for a few weeks the problem went away but now it's come back. I wondered about fuel starvation so changed the filter but that had no effect. Now I'm wondering about the injectors but have yet to find a supplier who lists them for my car. I do think it's more likely to be an electronic issue and would welcome any suggestions anyone out there might have. The car is 16 years old, one owner from new, only done 104000 miles and has a full Audi service history, could it be at that age when Audi electronics habitually fail and cost stupid money to replace? Help please.

[Magnet]

Hello Derek,

Before doing any other part replacements, I would be carefully inspecting all electrical connections near to and feeding the coil packs - no.1 in particular. 

Kind regards, 

Gareth,

 

[Nomi64]

I have a  1999 model 1.8 petrol A4 b5 saloon; again it's full Audi service history.. I serviced it myself 3 days ago, as its 20 years old not worth taking to the stealer ship anymore..my car is hesitant under acceleration and misfires when reved past 4k..any ideas? I didn't change the fuel filter. 

And maybe I should check all the earth connections. 

[bowline5]

One thing I've learnt about Audis over the years is that although the mechanics just keep going, there comes a point where some aspect of the ever more complex electronics fails and it can be a bugger to find. I eventually solved the misfire and tracked the problem down to an intermittent fault in one HT lead. I proved it by swapping a couple of leads and seeing the OBD fault codes report different cylinders. Audi of course wanted £46 + VAT per lead, Euro £54 (including) for the set of 6.

[Nomi64]

Thanks for the reply.. Its appreciate. 

Seems to be running fine at the minute. 

Its a 1999 model face-lift A4 petrol 1.8 manual. 

12 months mot

2 new tyres

New exhaust 

Mint condition 

117k miles 

I paid £507

Then spent £135 on a full service. I just need to change the petrol filter. 

Road was £145 for 6 months. 

Its a good car. 

Central locking is not working and srs airbag light is on in the dash.. But not the passenger side one near the rear view mirror. 

Front electric windows work. 

Alloys are clean. 

Interior is mint. 

Good car for the price.