A2 1.4 petrol BBY 48k misfire my experience and fix P0302

ashley7715

A2OC Donor
Good evening I thought Id share my A2 bby experience with you all as I've had various A2's over the years mainly the diesels but now own 2 petrols. Having used the forum and enjoyed the forum its good to give back where it may help others.
I bought a probably 3 years ago a 2003 A2 SE 1.4 BBY Petrol with 48k on the clock. The car had service history and was in pretty good condition not meticulous but great owned by a chap who didn't drive it much and I would say not an enthusiast but never the less it was looked after.

The misfire.
Being a low mileage car I thought great shouldn't have too many problems and in the main I was right It feels like an almost new car to drive - well it does now anyway.

The problem started after a long drive and only when the engine was up to temperature I would occasionally get the following errors.

5 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - Intermittent
16685 - Cylinder 1
P0301 - 35-10 - Misfire Detected - Intermittent
16686 - Cylinder 2
P0302 - 35-10 - Misfire Detected - Intermittent
16687 - Cylinder 3
P0303 - 35-10 - Misfire Detected - Intermittent
16688 - Cylinder 4
P0304 - 35-10 - Misfire Detected - Intermittent
Readiness: 0000 0000

---------- Once cleared I would mainly get the following error

16686 - Cylinder 2
P0302 - 35-10 - Misfire Detected - Intermittent

So I went down the route most do coil packs, a full service and additional earth but all were to no avail.

The issues when driving the car manifested as - AN IMPORTANT NOTE all the issues only happened when the car was well up to temperature when cold it drove fine.

1) The main problem for me was the hesitancy there was no low down torque if you pulled out and put your foot down there was a I would say dangerous delay before the car picked up.
2) Turning on the air conditioning seemed to exaggerate the problem (I think to do with the ECU adding more fuel with the air con on)
3) Not great fuel economy
4) Once when driving over one of those terrible rubber speed bumps the dash lit up EML light and I had to clear the codes to get it going again (this caused me to think it was an electrical issue)

After reading various forum posts I suspected burned out exhaust valves. I must say that I didn't go down the compression test route but took a punt mainly because I needed the engine hot to test thats not to say It cant be done I just went with my instinct. I also fumbled across the following link which I liked I have no affiliation with the company at all.


Based on this I had the head removed by a local mobile mechanic and I shipped the head up to J&E. A week later I had a call from Jonathan (j&E) and the head was ready to be returned, there were 2 valves replaced as they could not be reconditioned - im not sure if they were damaged or if they could not be ground and would not seat properly.

The mobile mechanic returned and fitted which I had ordered a new head gasket set, cambelt and water pump set, genuine water temp sensor, and genuine thermostat.

The results...

A very different car to drive points 1-4 above in the 3 thousand miles so far I have driven I have not re manifested. The main point being the hestancy / lul when you pulled off now its positive and you know you can fit in that a2 sized gap in traffic. The MPG seems much better too which is nice I must admit I've been treating the car to the E5 fuel but will try it on the E10 once Ive replaced the fuel filter.

In short I think the car now drives like it left the forecourt and it really is a great engine with a much better MPG.

The costs from J&E engineering is listed below - again I have no affiliation with J&E but Jonathan was excellent and I would recommend. I hope they enjoy the dartboard internal joke!
I do find it handy to get a cost when looking into issues and fixes. I will be emailing this write up to him also.

VAG CYLINDER HEAD BBY. CYLINDER HEAD SURFACE FLY-CUT. 30.00 6.00
VALVE SEAT RE-CUT. X16. 86.00 17.20
BRONZE VALVE GUIDE. X16. 88.00 17.60
VALVE GUIDE REPLACEMENT. X16. 60.00 12.00
VALVE STEM OIL SEAL SET. 16.00 3.20
EXHAUST VALVE. X2. 17.64 3.53
LABOUR: STRIP & ASSEMBLY, CHEMICAL CLEANING. 30.00 6.00

Total inc VAT was £393.17 (Dec 2022)

I hope this helps people along and keeps the A2's on the road.
 
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