misfire

[Yorkyni]

hi all need help, my car has a misfire, have cleaned EGR, Replaced injector harness, Replaced engine wiring harness, changed cam sensor(still shows intermit error), there is a misfire parked and holding revs at about 1200 rpm, when on the road there is a misfire around 56-60mph, the car has 195k on it. other than the misfire at that speed the car runs smoothly, could there be a injector fault or turbo fault I know the turbo is passing oil. I do have replacement turbo and a set of injectors of a BXE that had 107k on it and were very good condition(car rear ended).any help gratefully accepted as this is the only fault that is spoiling a Superb car.

[chimaera]

What fault codes do you get from a diagnostic scan?

[Otto_Octavius]

18 minutes ago, chimaera said:

What fault codes do you get from a diagnostic scan?

 

Related to this, I wonder if anyone can clue me up on 'clearing fault codes'. Bit ignorant on this and just from observing discussion, I'm completely bamboozled.

 

Surely fault codes are something which can alert you to something in the car which needs to be fixed or otherwise addressed? It seems to be implied that clearing fault codes is somehow a solution to a fault code problem? What is the point of them then? 😐

Edited 3 July, 2019 by Otto_Octavius
Apologies to OP for going on a tangent

[langers2k]

@Otto_Octavius - some fault codes are less important and don't always mean much or are related to previous work.

 

It's good practise to make a note of the codes, clear them and see which, if any come back as they're likely to be more helpful.

[Yorkyni]

3 hours ago, Yorkyni said:

hi all need help, my car has a misfire, have cleaned EGR, Replaced injector harness, Replaced engine wiring harness, changed cam sensor(still shows intermit error), there is a misfire parked and holding revs at about 1200 rpm, when on the road there is a misfire around 56-60mph, the car has 195k on it. other than the misfire at that speed the car runs smoothly, could there be a injector fault or turbo fault I know the turbo is passing oil. I do have replacement turbo and a set of injectors of a BXE that had 107k on it and were very good condition(car rear ended).any help gratefully accepted as this is the only fault that is spoiling a Superb car.

hi Fault code is "sensor G40",  P3007-000, no signal- intermitant.

[chimaera]

2 hours ago, Otto_Octavius said:

 

Related to this, I wonder if anyone can clue me up on 'clearing fault codes'. Bit ignorant on this and just from observing discussion, I'm completely bamboozled.

 

Surely fault codes are something which can alert you to something in the car which needs to be fixed or otherwise addressed? It seems to be implied that clearing fault codes is somehow a solution to a fault code problem? What is the point of them then? 😐

Clearing fault codes is (usually) done for two reasons. One is to clear the code once the underlying fault has been repaired: this would be a normal part of the repair procedure. The other would be as @langers2k says to see if the fault is still happening e.g. to see if an attempted repair has resolved the problem, or if it's an old code that was never cleared. Also, if the cause of the fault is still there, a cleared code will come back.

 

At the end of the day, the point of fault codes is to alert the mechanic to the existence of a fault that the relevant ECU can detect and flag up for further investigation. There are plenty of faults that won't result in a fault code: it could be in a system that has no diagnostic capable elements; or it could be that the system has failed to a plausible state and the ECU doesn't see an error.

[chimaera]

1 hour ago, Yorkyni said:

hi Fault code is "sensor G40",  P3007-000, no signal- intermitant. 

First hit on Google is http://wiki.ross-tech.com/wiki/index.php/19463/P3007/012295 - camshaft position sensor failure. If you've replaced the sensor and the error is still there, it's either the fuse or the wiring, and all the other stuff you've replaced was probably not needed. It's not going to be injectors or turbo, so unless there's another problem that requires those I'd suggest you see about getting your money back.

 

What engine code are we dealing with here?

[Yorkyni]

Bxe. engine. 

[3T51704x4]

Could be the cam is worn or has worn a hole in a hydraulic tappet causing the G40 error. Once it gets bad, you will hear noises from the intake like a loud popping.

Have a look at the smooth idle readings in measured value blocks to see if one injector working harder than the others.

Would be worth scoping G40 and G28 to get a better picture too. May have missing sender wheel areas.

Edited 6 July, 2019 by 3T51704x4