Another 1.4 Misfiring

[lancs_lad]

Set off this afternoon and while engine was still warming up it developed a misfire as I pulled away from traffic lights in 1st gear. It was so slight I thought I may have been mistaken. 2 or 3 minutes later in 4th gear put a bit of throttle on and again detected a slight misfire (just before engine was fully warm). No sign of any warning lights or anything but having read other threads on this engine I'm not impressed and am already starting to look at my next choice of car.

Car is now booked into the local dealer (next Friday ) for them to have a look.

[RW1]

This is probably not what you want to read but it may help with Friday's visit to the dealers.

Sounds a bit like the problem I had back in late June/July. Unfortunately its not solved but there is one distinct difference about the known problem to yours. Friday's humidity across Lancashire & Yorkshire wasn't below 20% humidity level with the air temperature above 12'C. The condition at which it usually occurs.

The fault is an engine judder at about 35'C coolant temperature while the warm up temperature is rising. It continues mildly until the engine is warmed up. You will have read my post elsewhere about it. I also didn't on a lot of occasions get an EG Warning lamp in the dials until on one occasion decided to push for full throttle and it lasted for a few seconds while the engine shuddered. There should from my experience be logged faults in the Engine ECU memory for faulty coil packs (not true fault from subsequent experience), even without the EG Warning lamp showing.

I discovered something today while out logging my Engine ECU software characteristics before having "Workshop Campaign 24s4" flashed in my engine ECU at the end of the month. Until the engine coolant temperature is at 35'C, the SuperCharger is disabled. This corresponds to about 75 seconds from an engine cold start at an outside air temperature of 12'C – 15'C. The dash temperature gauge doesn't register 35'C but it can be seen in a VCDS (VAGCOM) measuring block fields.

What I found today is the SuperCharger Regulating Flap (J808) is fully open until 35'C, thus disabling the Supercharger. So the 1.4TSI 160PS runs in TurboCharger mode only for the first 60 to 90 seconds depending how cold the day is and when 35'C coolant temperature is achieved.

At 35'C coolant temperature, the SuperCharger Flap is allowed to start operating and therefore boost rises from about typically 1.3 bar to 2.1 bar at 1,500 rpm. This is a step change as the engine goes to normal boost operation.

What I conclude from results today is that the SuperCharger/ECU map is some way is creating a mixture when it kicks in at 35'C coolant temperature that is not quite combustible until the engine is further warmed up.

In the memory, the dealer's workshop will see Coil Pack faults for a cylinder or cylinders. Which as written above have not turned out to be the case since July. The original coil packs are still fitted and have operated normally since.

Whilst your problem may not be the above, it may be worthwhile drawing the dealer's workshop attention to:-

Judder after Cold Start.JPG

There was a spate of this fault in Germany and UK including my Scirocco, when it was very dry last mid June to Early July. Not many, about 2 dozen at most. The forums reports suddenly started appearing at the time. Since then it's gone quiet and so has my engine ceased to judder on cold start warm ups. Humidity has never dropped below 20% since 12th July locally when mine stopped but I notice on dryer days, the VCDS logging is picking up increased misfires by 300% when it nears 20% humidity levels like 10th October (23%). I've swapped coil packs around and it had no effect on moving the fault to another cylinder. The cylinder reporting a fault was any cylinder at random.

The new software 2023712/1 refers to, is not "Workshop Campaign 24s4" but a further update still to be released unless it has happened in the last week. 24s4 will be done on Friday as part of the dealer visit. Which is a good move (if not, make sure they do it but note my post on aftermarket engine ECU tuning maps elsewhere (Bluefin)). 24s4 appears to have solved a lot of the 1.4TSI 160PS problems by sorting out the software coding for the Knock Sensor and Fuelling.

C.

[lancs_lad]

Thanks for that, I may just print it out and present the dealers with it on Friday

[lancs_lad]

Having re read your reply my misfire occurred around 5 minutes into my journey when the temp needle was rising. The second misfire occurrence (in 4th gear) was just before it reached full operating temp so may not be the same issue as above.

[RW1]

Thanks for that, I may just print it out and present the dealers with it on Friday

-------------

Looked back at the records at the time, 2 to 4 mins is when it occurred, 35'C thro' to 65'C.

I have a feeling the problem for mine was a combination of conditions with an injector very slightly blocked. New injectors were introduced by VW in Mar'2010.

C.

[johno]

Set off this afternoon and while engine was still warming up it developed a misfire as I pulled away from traffic lights in 1st gear. It was so slight I thought I may have been mistaken. 2 or 3 minutes later in 4th gear put a bit of throttle on and again detected a slight misfire (just before engine was fully warm). No sign of any warning lights or anything but having read other threads on this engine I'm not impressed and am already starting to look at my next choice of car.

Car is now booked into the local dealer (next Friday ) for them to have a look.

You may benefit by having a read of my thread, after 5 trips to dealer with exactly this issue (software, coils, fuel pump, and injectors looked into) and no improvement, they finally put in a new engine (2 weeks in shop) so far so good, not as bad as before, still appears to have a slight issue when accelerating from cold. I feel it may be a supercharge problem, as almost a back fire occurs. May be something that I will have to live with and part of the engine performance.

[johno]

Apparently the solution to the 1.4 misfire problem (with exhaust light activation) is to only accelerate gently, while engine is warming up until temp up to 90, then it will run smoothly.

[lancs_lad]

The diagnosis is a misfire on no 4 cylinder. The remedy is to change the coil pack on no 4 cylinder. The misfire was detected on the software and was the only incidence. It's now booked in for a new coil pack on Tuesday so we'll just take it from there for now and hope there's no recurrence.

[johno]

My problem was only resolved with new engine ( after coils,injectors and fuel pump changed) and as I stated no issues as long as I gentle acceleration until engine warmed to 90.