Engine misfire.

Hi everyone, coming home from work last night my W reg 2.0 Sport APK engine code Bora developed a serious misfire. Managed to get home and code read it which gave

16688 P0304-35-00 cylinder 4 misfire

Cleared the code and started the car and the fault returned.

Following the advice of a friend whose a VW technician I replaced the coil pack with a new genuine VW coil pack.

Went for a drive and at first the car was a bit lumpy but it son settled down and it drove really well. Code read it when I got back and it flagged a coolant temp sensor error, cleared that and tried to start it again but it wouldn't and when it did the revs rose to about 2000 rpm and just stayed there.

Cleared the codes again, swore at it, packed my tools away went to put the car in the garage and no probs just i bit uneven.

Error code now reads

17990 P1582-35-00 Idle Adaptation limit reached. Replaced one hose that was badly fraid but just the same so any suggestion please.

You need to double check it for air leaks after the Air Mass Meter and if you do not find any, clean and reset the throttle body in Basic Settings 098.

Hi Crasher,

thanks for the advice. Will have a look and see if I can spot anything.

Well, 1 month on from a new VW coil pack and having the garage reset the throttle body settings the misfire is back!

The code read came up as

16684 P0300-35-00

16688 P0304-35-00 cylinder 4 misfire

Does this mean the coil pack has failed again and if so is there anything that might cause it to fail? Or alternatively should I be looking at something else?

Thanks.

Fit new leads.

Hi Crasher, missed the obvious there didn't I.

Anyway, besides replacing the lead I also took the plug out and found that it was very heavily oiled up. I borrowed a compression tester and checked number 4 cylinder and the reading was about 154 psi so that seems fine. The car does use a lot of oil though so I presume that it is the valve stem seals leaking.

What sort of price would it be to have the head off and check replace the seals and any other gaskets etc inc the timing belt? The car maybe 10 yr old but it's only done 54000 miles and has been serviced about every 6 months by the 1 previous owner.

Thanks for your help.

Those engines do burn oil and it is often the rings. Some garages (like myself) have the gear to do valve stem oil seals with the head on and during this job it is possible to asses the condition of the rings by the cylinder blow by.

Well, I've had a further look at the car and there was a bit of "mayo gunk" in the filler cap which didn't surprise me with the low mileage of the car so I cleaned it out and also took the breather housing of and found that the hose from it was just about totally blocked with it. This has now been cleaned out as well.

I presume that this would cause a pressure build up and forcing a bit of oil past the valve stem seals and fouling the plug up.

The coolant level is not changing and neither is it changing colour plus the coolant temp stays constant whether sat in traffic or having a blast on the motorway so I think that the headgasket is fine.

I've treated the car to a full service using genuine parts so I'll see how things go as the the tickover just fluctuates a fraction.

The misfire is back!

Had been driving for about 15 minutes when it started again. Figuring it was the issue with number 4 spark plug burning oil again I got the recovery guy to clean the plug but that didn't cure the misfire.

I managed to limp it to our local garage where the guy had a look and couldn't really determine a particular cause. A code read flagged up multiple misfire in cylinder 2.

He suggested the suspects of valves or the ECU. He says he will likely need to take off the head to have a proper look but I am loathe to do that for the obvious cost issues, particularly if he doesn't find anything.

He says it seems to have settled down a little although its still rough. He also says it is driveable but I don't want to risk any further damage.

Any suggestions would be great as I need to make a decision on what work to have carried out. Thanks in advance.

Ask him to do a compression and then a blow by check; this will give you a pretty good idea if the valves or rings have a problem. Was the number 2 plug oiled up? Did you fit new leads like I said previously?