It started to misfire about 3 weeks after exhaust put on the car. I've replaced the spark plug and the coil pack and it's made no difference. Any suggestions

 

Thanks in advance

Sam dosser

Despite you fitting the exhaust prior to the issue starting It doubt it has any connection.

 

Misfires, hesitation, tick over issues ect. can and do occur randomly and in the main due to bad connections,

 

To find the cylinder that is troubling you, is with the engine running unplug one coil pack at a time ( don`t worry you will not get a shock) and look out for which one makes no difference to the engine note whether it is connected or not.

 

Once identified you can then check for spark by leaving a coil pack with spark plug resting on the engine with the outer metal body of the plug touching the engine and start the engine and check for a good spark.

 

If a good spark then move on to the injector connection for that cylinder, it will very likely be green and require cleaning with WD40 or simliar and a small blade to clean it all up, if again when trying it the problem persists it could be a failed injector, so at the injector connection you need to take a resistance reading, with a multi meter, it should be around 14 Ohms if open circuit its a gonna and will need changing. ( search on here for injector swaps have done a few tech threads myself)

 

If when checking the spark there was not one, try again but with another coil pack, if still the same check the connection on the ptu at the front left of the engine, usually the lower left hand connections can go green and cause issues, again clean with WD40 or similar and a small blade.

 

If any of the stages above provide a failure then no point moving on until that particular issue is resolved or you will end up going around in circles, in fact if you do find that happening take as break and start all over again, that 5 minutes away will often be all it takes to find it.

 

Jeff TT

Thanks Jeff I have already changed the spark plug and coil pack and still makes no difference.

Thanks Jeff I have already changed the spark plug and coil pack and still makes no difference.

 

 

Have you identified which cylinder it is though? thats the key to finding the issue.

 

Jeff TT

Yes I have topside on the passenger side.

Yes I have topside on the passenger side.

 

 

Ok so have you confirmed the spark on that cylinder by the method above?

 

 

Jeff TT

No not yet but I have replaced the plug

No not yet but I have replaced the plug

 

Ok does not prove the coil pack or the ptu signal to it yet.

 

 

Jeff TT