1.4 TSI misfires.....

[CrazyDave]

Just thought it might be useful for you guys to hear our trials and tribulations with a 1.4TSI car recently. Mostly we've been watching on the sidelines whilst a dealer tries to find the problem but the car has just dropped out of warranty so it's time for us to work some magic!

The car has had all kinds of engine running problems from new and still doesn't run very well. The dealer seems at a loss as to what's causing the actual problem with how it runs.

Symptoms: Misfires at idle to varying degrees when cold or hot even after numerous software patches at VW....

Parts fitted so far......
Plugs, coilpacks, turbo, boost control valve all new genuine.

It's always the same cylinder that misfires and it runs fine whilst driving.

We're about to remove the injectors for flow testing and cleaning to see if this is causing the problem.... we'll keep you posted as it's not the first one we've heard about and I'm sure a few of you will be having the same problems.

[davo160]

Intresting to see what you find out mate . I have had my injectors swopped on mine, then new software updates That did not cure it still the same. New coils and plugs did however (well so far so good touch wood! will see how it goes !! )

[CrazyDave]

Maybe not related at all but these plugs came out of a Golf mk5 1.4 16v. This car is running on Tesco 95 all the time......

DSC04549.jpg

The picture doesn't really show the bright yellow colour that well, but trust me it is very unusual and must be something to do with the additives being used.

The Jetta 1.4TSi isn't due back in for a few weeks, but I'm very keen to get the plugs out and also find out what fuel it's running on.

[RW1]

Pulled the spark plugs again on mine yesterday.

Was running on Tesco 99 RON recently and had a roughish engine with the fuel.

This is what I found after the engine was stopped following a 1 hour drive, a month ago .......

Tesco 99RON - No3 Cylinder spark plug - well sooted up but the tips clean

1 Tesco 1-4TSi Plug No3 - 02a.jpg

Tesco 99RON - No4 Cylinder spark plug - ditto.

1 Tesco 1-4TSi Plug No4 - 02a.jpg

That carbon built up if on the cylinder walls will not be doing the FSI any good.

Put the plugs back in without cleaning them.

Then a few weeks ago changed to Texaco 97RON for two tanks and the current tank full is Texaco 95RON. The engine runs much smoother than Tesco 99RON and the Texaco 95RON is slightly smoother than Texaco 97RON.

Although not easy to see, the carbon build up had been reduced and gone slightly grey. This is in 1,000 miles approx between the two sets of photos. The engine again had been stopped after a 1 hour run of similar conditions to the Tesco running above.

Texaco 95RON - No3 Cylinder sprk plug

2 Texaco 1-4TSi Plug No3 - 01a.jpg

Texaco 95RON - No4 Cylinder sprk plug

2 Texaco 1-4TSi Plug No4 - 01a.jpg

This time gave a helping hand and cleaned the plugs. The engine ran beautifully smooth and responsive afterwards.

No.1 cylinder coil pack is a right one for getting out. You need to remove two screws to move the oil breather pipe out of the way of the area above No1 cylinder (Torx 30 bit) and disconnect two sensor connections.

It helps to have the coil pack puller tool - T10094A, otherwise its fairly certain the coil pack top will be damaged by trying to lever out. The packs are a stiff tight fit and a special grease on the plugs also hinders removal.

Coil pack and T0094A puller tool.

DSCN7623a.JPG

C.

[davo160]

Intresting find !
Makes me now wonder what fuel to be putting in mine now ???
what have you always run yours before this ?

[RW1]

Since November 2009........

000013 - 001170 miles Texaco 97RON (Running in period)

001170 - 004422 miles Tesco 99RON

004423 - 005525 miles Texaco 97RON
Change prompted by rough running in 3 VW engines, 1.4TSi, VR6 & 1.8tr 8v, late June'10. Plus had 1.4TSi engine misfires in hot, very dry weather in late June with fault codes as described elsewhere.

005526 - (005614 now) miles Texaco 95RON

For a long way back to 1979, always used Texaco but this was because it was the local petrol station brand round the corner. Good clean, normally coloured spark plugs & piston crowns at every service. Then start using Tesco 99RON because of its cheapness just after it became available some 3 years back in the VR6 & 8v. Spark plugs & Crowns still clean but with a reddish tinge. Both the VR6 & 8v ran fine on it until May this year. When they along with the 1.4 started to feel just that bit rough and little bit noisier.

Also tried using Total (rough), Shell (carboning leading to poor starting) , BP (Sooty), Esso (Dog rough) & Sainsbury's (OK but too far away to fill up every time.) along the way. Each time would revert to Texaco to find the problems went away.

C.

[RW1]

Stuck the Laptop in the passenger footwell and went for a data logging run again of 100 mins . Similar day at 21'C and similar routes on both occasions.

Last time was with Texaco 97RON, this time it was Texaco 95RON.

Last time logged two misfire events as the throttle shut on the overrun with no fuel being injected. No fault code recorded in the Engine ECU memory.

This time logged 10 misfire events.
Two misfires events as the throttle shut on the overrun with no fuel being injected.
Eight with throttle being opened or throttle steady with small angle of opening and fuel being injected in all eight events.
No fault codes recorded and no Exhaust Gas warning lamp on the dash instruments.

Never felt a thing in the car whilst driving, the engine ran smoothly and responsively as with 97RON. The engine ran slightly hotter oil temperatures by about 2'C to 4'C, the coolant was similar to the 97RON readings.

The misfires above with fuel being injected (cylinder washing) from this little exercise today have persuaded me that the next fill-ups will be with Texaco 97RON despite the 1.4TSi running on 95RON very well from the driver's point of view.

(1 – While investigating when running 97RON, the coil packs were swapped, that had no effect on which cylinder misfired.)

(2 - Misfiring with injected fuel leads to lubricating oil being washed off the cylinder walls. This has lead to piston ring failures where the misfiring has been persistent.)

C.

[RW1]

Just before finishing the tank of Texaco 95RON fuel, decided to check the plug gaps against the VW spec of 0.8mm - 0.9mm (31.5 - 35.5 thou). All were about 36 thou.as were the new spares in their boxes. Shortened the gap of all four to a 31 thou (0.79mm) gap. Engine ran better but the misfire rate did not improve.

ETA: Finally in September 2011 settled on a gap of 0.74mm (29thou) and its really smooth! In June 2012, the gap has been reduced to 0.70mm with further improved results including mpg improvement.

(NB: You have to be very careful re-gapping fine wire spark plugs that have very small diameter platinum or iridium alloy electrodes. Feeler gauges or wire gauges should be used with gentle care when testing the gap by comparing with the feeler gauge. Otherwise the central electrode tip will be damaged.).

The revised NGK plug 03C 905 601A VW have introduced (September 2011) on the Scirocco 1.4TSi 160PS is NGK PZFR6R8EG. "8" refers to the plug gap... 0.8mm. Link to description

The safe way of gapping these wire tip electrode plugs. Note the comment about breaking the tip if you are rough with them.

Filled up a full tank of Texaco 97RON yesterday for a run down to DG Autotech to provide a reference engine condition for the misfiring 1.4TSi due in as written in the topic's first post above. The VCDS logs showed a significant reduction in misfire on the way there this morning.

On arrival, the obligatory mug of tea was soon to hand.

Next, out with the coil packs and plugs (my job for the day) .........

DSCN7906a.JPG

Engine ready for the insertion of the borescope to inspect the cylinders through the spark plug holes ......

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Then Dave & Graham set to work with the borescope instrument.

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The good news on this 6,000 mile engine .... no scoring of the bores.

But there were some interesting observations ......
- Plugs run hot and plug tips look scorched after the run down from Manchester to Droitwich.
- Inlet valves have sooty deposits on the inlet manifold side and some valve are pitted on the seating face.
- Exhaust valves - Number 1 cylinder exhaust valve had interesting differences in coloured deposits to the others.
- Top of the cylinder walls are not consistent, part of the circumferences are sooted, while other areas are shiny clean metal.
- The injectors are not as clean as expected around the 6 fuel outlets of each injector.
- The bores still show strong honing marks.

No obvious mechanical reason for the occassional misfires on this engine.

I'll let Dave go into the detail found.

C.

[davidscirocco]

hi all im sorry for being soo noob but im no mechanic so i have 2 questions to ask.1st. does all the 1.4 rocs have this problem? 2nd. how can i know if i have a misfire? like how does a misfires sounds like? can u post me a video or a sound to listen and see if i have the same problem?

[RW1]

All 1.4TSi 160PS have it? .....
Not looked at other Sciroccos.

The misfires I am recording are by using VCDS data logging and measuring block fields. When driving the Scirocco they can't be felt or heard dispite catching a glimpse today of it happening on the PC screen in front of Dave. The misfires occur on shutting the throttle from very small openings in the steady throttle condition, ie. 5º to 7º opening to 2º. They last for 2 to 50 seconds on one, maybe two cylinders. They do not generate a fault code or put the EG dash warning lamp on.

What was being investigated as part of today was for clues as to why my VCDS logs show engine misfires. None were found. We did note while the engine was idling, that the tailpipe gases were occasionally "fluffing" a beat, ie missing, but that is not registering on VCDS measuring block misfire fields.

In the past (late June/early July) I have had an engine stutter during warm up but that has now gone on its own accord (since it starting raining again). That stuttering misfire condition gradually built up in strength over about 3 weeks until it finally shook the engine and twice the Exhaust Gas warning light came on. It generated coil pack failure fault codes on different cylinders. Those misfires could be felt each time in the car. Its a specifically known condition only during early warm-up (2 - 4 mins from cold start) when air humidity is low (below 20%) and at certain air temperatures. ( link )

My engine ECU is at 4009 software standard and needs 5860 standard of software. Thats the next step at the oil service at the end of October as the update adds more fuel at certain operating conditions of the engine to overcome misfire. I'm not concerned as the misfire condition with my engine is generally with no fuelling present and therefore cylinder wall washing is not occurring. In part thats confirmed by the cylinder inspections today.

C.

[davidscirocco]

hm.... ok. my car will go for the big service soon. shall i ask them to check about this misfire? or tell them to update my ECU? what do you suggest?

[RW1]

hm.... ok. my car will go for the big service soon. shall i ask them to check about this misfire? or tell them to update my ECU? what do you suggest?

The advice has already been posted here........ link in the middle paragraph of this post.

C.

[davidscirocco]

ok thank you

[CrazyDave]

Just sorting out the inspection video.... be along soon

[CrazyDave]

OK here it is......for the record

[youtube][/youtube]


Edit: Added some more info to the front of the video, normal driving cycle and a few notes.

[RW1]

Had 24s4 update to the engine ECU a couple of weeks back. General conclusion is that it is a smoother engine as a result with the throttle feeling more connected to the accelerator pedal. No mid range boost dip being noted when driving like others after the change (See boost levels here). Sports mode and accelerating through the rpm range is improved. The setting off lurch due to the engine-1st gear/2nd gear engagements has gone.

Had time to look at the long string of misfires that were being noted prior to 24s4 update after about an hours running. Occurring when the throttle is shut at 2,000 - 2,500 rpm in 7th gear when running very light throttle settings, typically 10% - 15%. They were still the same post ECU update.

Did some higher speed logging at 0.3 seconds on the lambda probe, ignition retard and ignition voltages. I cannot see any evidence of a misfire actually happening.

What is characteristic of these strings of cylinder misfires is they appear only to occur when the throttle is shutting from 10% - 15% to closed AND the rpm drops by 40rpm. If the rpm remains constant at the point of closure, the string of misfires does not occur. So I've concluded that the throttle shutting coupled with a small rpm drop is disturbing the engine ECU misfire algorithm.

The algorithm works out misfires over a period of engine revolutions.It then detects rpm dropping on a particular cylinder detonating with slowing rpm and interpretates this as a misfire. A known short coming of this approach to true misfire detection.

C.