1.6 FSI misfire and cutting out

freebster

New Member
Hi all, I signed up to this forum as I currently have a members car (Chipper) stranded on my driveway since Christmas.

He has been having hot starting problems for sometime, but it lost engine power and cut out a few miles from my house. I was able to restart and rescue the car after letting it cool down.

VCDS gives a couple of codes, 16687 P0303 Cylinder 3 misfire and also 17428 P1020 Fuel Pressure Regulation Control Range Exceeded.

After clearing the codes, the car will restart and will run smoothly with no misfires until it starts warming up. The misfires become progressively worse (cylinder 3 only) and eventually the engine will splutter to a stop. It will also be very difficult to restart - usually will have to wait an hour or so for the engine to cool. Cranking time is always quite long too.

I’ve swapped spark plugs and coils between 2 and 3 to see if there was a spark issue, since I can smell fuel from the exhaust. I’m suspecting injector on cylinder 3 but I can see how complex these FSi engines are, having read the fantastic advise being given out by knowledgable members.

Any help on this would be much appreciated by both myself and Chipper. 😀
Thanks.
 

Chipper

Member
Really appreciate all your investigations, it would be great if anyone can help us get to the bottom of this.

Many Thanks
 

PlasticMac

Member
Hi all, I signed up to this forum as I currently have a members car (Chipper) stranded on my driveway since Christmas.

He has been having hot starting problems for sometime, but it lost engine power and cut out a few miles from my house. I was able to restart and rescue the car after letting it cool down.

VCDS gives a couple of codes, 16687 P0303 Cylinder 3 misfire and also 17428 P1020 Fuel Pressure Regulation Control Range Exceeded.

After clearing the codes, the car will restart and will run smoothly with no misfires until it starts warming up. The misfires become progressively worse (cylinder 3 only) and eventually the engine will splutter to a stop. It will also be very difficult to restart - usually will have to wait an hour or so for the engine to cool. Cranking time is always quite long too.

I’ve swapped spark plugs and coils between 2 and 3 to see if there was a spark issue, since I can smell fuel from the exhaust. I’m suspecting injector on cylinder 3 but I can see how complex these FSi engines are, having read the fantastic advise being given out by knowledgable members.

Any help on this would be much appreciated by both myself and Chipper. 😀
Thanks.
When you swapped 2 and 3 coil packs (and plugs), did the miss fire move to 2?
If so, replace the coil pack that's now on 2. Better still, check the date code on the coil packs, and if they are the originals, replace all 4 with Bosch or NGK, not ebay cheapies. (If the plugs have not been changed in the last 10,000 miles, they should also be replaced again, I'd go for NGK).
Does it run on 98/99 octane, Super Unleaded?
If not, it should. This is vital on the FSI.
Mac.
 

freebster

New Member
Thanks for your reply Mac.
I was hoping the misfiring would follow the coils and plugs, but the misfire remains on cylinder 3

Chipper did tell me that his wife did filled the car up fully with regular unleaded prior to driving it some 50 miles. It then cut out after leaving the motorway. Do you think this could be the cause? Is it really that fussy about the fuel that it can cause misfiring on Cylinder 3 only?

@Chipper Can you advise when the plugs were last changed? The coils look original.

Thanks again.
 

PlasticMac

Member
I don't think that one fill is significant.
Any chance you can get a compression test done on cylinder 3, and, preferably the other cylinders too?
As you say, does seem to be cylinder 3 specific, and not coil pack/plug related.
If compression test is OK, wiring to cylinder 3 coil pack is probably next.
Mac.
 

Andrew

A2OC Donor
Compression test and post results has merit.

Another suggestion. A look at Ross-Tech for P1020 mentions 'Fuel Suppy Pre-Mesh clogged' and assuming this translates to fuel filter I would renew the fuel filter, unless you know it has been renewed recently. May need doing anyway, cheap enough and can only benefit.

Andy
 

PlasticMac

Member
Just a thought, look carefully at the connector, that plugs into cylinder 3 coil pack. Look for damaged or pushed back pins. Give each wire core a gentle pull, there should be no give. Any movement indicates the socket pin is not seated.
Pins and shells are available, but you'll need an extractor tool.
Mac.
 

Chipper

Member
Thanks all

From the service history I have the coil pack was done in 08 @65k and Plugs in 11 but I don’t have the mileage for that.

Jeff
 

freebster

New Member
Thank you Andy and Mac,
I will do a compression test.
I will also check the cable/pins on the coil connector for cylinder 3.
According to VCDS, there is no misfiring for the first few minutes from cold, but then the count starts to increase as the engine warms up. Engine revs well and there’s plenty of power when it’s not misfiring.

Thanks again and I’ll report back the compression test results later in the week.
 

Exe_Chris

Member
I've been scouring the site for a how-to for the fuel filter change but all I can find is this post from @chb (https://www.a2oc.net/community/index.php?threads/fuel-filter-change-1-6fsi-very-easy.10682/) where a guide is referenced and reports on how easy it is but there isn't a link. Can anyone help me find the thread?

Many Thanks
It's just in front of the driver's side rear wheel. Ideally jack it up to make things easier but I suspect it can be done without. The filter is about as long as a coke can and should be openly visible. The fuel lines are removed by pushing in the clips at each end and yanking them off (sometimes they can be stubborn). You may manage with fingernails, or may want to use a screwdriver or something. To put a new one on just push it into the hoses making sure the grooves are cleared. The new filter shouldn't cost much more than £10.
 

Andrew

A2OC Donor
I've been scouring the site for a how-to for the fuel filter change but all I can find is this post from @chb (https://www.a2oc.net/community/index.php?threads/fuel-filter-change-1-6fsi-very-easy.10682/) where a guide is referenced and reports on how easy it is but there isn't a link. Can anyone help me find the thread?

Many Thanks
Nothing jumps out from a search but to be honest the first post in the thread you linked is quite a good 'How To', pictures were not as abundant back then.

Andy
 

freebster

New Member
Hi all,
So I’ve checked the wiring, all seems good and pins and connectors all seem to be in good condition with little to no movement.

Started the car and it runs perfectly for the first couple of minutes. Then the misfires start, very few at first and then increasing frequency until it eventually dies at about 110 degC engine temperature (VCDS). By the way, I’ve never know the cooling fan to come. No fault codes though other than what has been previously reported.

So with a warm engine, pulled the spark plugs, number 3 was a bit more sooted up than the rest.

Compression results as follows.
Cylinder 1 = 200psi
Cylinder 2 = 205psi
Cylinder 3 = 255psi
Cylinder 4 = 260psi

Looking forward to hearing if we are any closer to diagnosing what’s causing the misfire and eventual stalling (with no hot restart).
Thanks
 

Rusty911

A2OC Donor
Is that not rather warm? I know FSI's are a tricksy breed, but 110 sounds toasty. Pro-Boost dials back temps I know, is this why?

Anyway, my gut is that this can't be a single cylinder issue, but another overarching one in addition to the cyl 3 thing. I'd expect any car to run on remaining three cylinders (badly) almost forever: in itself I wouldn't expect that to stop the thing running unless of course the ECU cuts the engine after a certain period / number of misfire(s)?

Would an ECU cut engine if temps got too high? What does FSI usually run at?

My latest FSI certainly has had issues around loom / ECU plug area but I'd be amazed if this allowed the car to initially run ok and then go downhill until it stalls out.

Be interesting to pop a Pro-Boost on. Would eliminate all ignition issues, all fuel supply issues (although as it pulls fine when cold, it can't have these anyway other than tank vacuum build-up), nearly all loom and ecu connector problems.

I have to say, that's why I keep a Pro-Boost, not to use as an ECU in itself, but as an extra diagnostic tool.

Sorry, that was a rambly bit of waffle, just thinking aloud so to speak.
 

Nye

Member
I trust you've checked the earth strap? As PlasticMac says, check all the connectors; I had cracked insulation around two wires that caused problems. I also found that packing the wires back into their allotted positions helped. I agree with the suspicion that it's an electrical fault so I think you'll have replaced all the coils and plugs before you get to the bottom of it.
 

PlasticMac

Member
FSI does indeed run at 110 degrees although it'll only show 90 on the gauge. ProBoost reduces that back down to 90.
High running temperature, plus high compression, plus high octane (98/99) = high thermal efficiency.
The thermostat is electronically controlled, to maintain an almost constant 110 C, compared to the +/- 10 - 15 C swings with a "traditional" wax stat.
Mac.
 

Andrew

A2OC Donor
Hi all,
So I’ve checked the wiring, all seems good and pins and connectors all seem to be in good condition with little to no movement.

Started the car and it runs perfectly for the first couple of minutes. Then the misfires start, very few at first and then increasing frequency until it eventually dies at about 110 degC engine temperature (VCDS). By the way, I’ve never know the cooling fan to come. No fault codes though other than what has been previously reported.

So with a warm engine, pulled the spark plugs, number 3 was a bit more sooted up than the rest.

Compression results as follows.
Cylinder 1 = 200psi
Cylinder 2 = 205psi
Cylinder 3 = 255psi
Cylinder 4 = 260psi

Looking forward to hearing if we are any closer to diagnosing what’s causing the misfire and eventual stalling (with no hot restart).
Thanks
Just catching up with things.

The compression test readings generally look healthy, but the main thing is nothing is odd about cylinder 3 and focus will have to turn elsewhere.

Out of interest your pressure readings (rounded) in bar for comparision with the workshop specification.

Cylinder 1 = 13.8 bar
Cylinder 2 = 14.1 bar
Cylinder 3 = 17.6 bar
Cylinder 4 = 17.9 bar

image.jpeg


Oddities in you figures I suspect are down to measuring procedure and testing equipment and I would not dwell on them.

Andy
 
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