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MG MGF Technical - ODBC II missfire error code

Does anyone know what these actualy mean ?

My yellow engine light came on about 5 mins after driving off. I bought an ODBC II u380 off ebay and it read the codes. The 2 codes were p0303 and p0313 which is missfire detected on cylinder 3 and generic missfire fule level low

I reset and the light is now off.

The car is regurarly serviced by the old MG dealer and I only do about 4,000 miles a year so a bit surprised.

Its a mgtf 1.8

Any help gratefully recieved.

I have to say the reader is excellent so well chuffed


I'm making the assumption here that its some duff fuel, or just issue on starting.

I'd assume if its the plug / lead / dist / or coil pack it would continue until they were replaced, or if I swap them I would see the fault move, and as its not re occurred its nothing to be concerned about.

Car only has 20,000 miles and 5 years old with annual MG dealer service, so would expect plugs etc etc fine, but just wondered what anyone else thought.

whilst it could be fine, a problem could also still be there. Codes do not always show up even if tehre is an obvious fault. I had a coil pack failure that the coe only showed under certain odd conditions, but the misfire was very obvious.

The OEM leads are frankly pretty poor and tend to go pourous after 3 or so years, which can lead to misfire. Whilst the leads are probably past their best, and any movement of them in investigating this fault could make them worse, I doubt they are the key problem on their own. That said if you choose to replace them, then magnecor or a similar quality silicon lead are your best bet, and probably cheaper than OEM.

The plugs are supposed to last up to 60k miles, but after 20k to 30k the performance definitely tumbles. As your car is a TF and over 4 years old, I assume you have had the major "c" service with cam belt change, and generally the plugs are replaced then. So again it's unlikely to be your problem on it's own, unless the plug in cyl 3 is damaged. Worth checking the service sheet to see if the plugs were replaced. NGK Iridium plugs work pretty well and are reasonably priced if you want to replace

The coil packs are however a regular source of engine misfire codes if they have or are beginning to fail. Until they actually fail or are really bad, you may not even notice the misfire (at least I didn't initially anyway). IIRC your aged car has the coil packs over the plugs and so access is fairly easy. The odd one is the second cose, which I would not expect from a failed coil, so need to be carful you dont replace things for the sake of it and waste money. The coil packs are part no NEC100730 which was superceeded by NEC000120 fitting over plugs and requiring 2 plug leads. I am assuming you have the TF135 from your description, but if not then the vvc TF160 coil is part no NEC000130 with a red sleeve.

Cleaning the connectors may help as well.

As you have a fuel code, you might want to think about the fuel filter, or injectors. Not sure I can help much here as I don't have much experience of that on the F/TF


This thread was discussed between 02/06/2009 and 04/06/2009

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