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Massive Misfiring Issues

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saiifqadiir001

Passed Driver's Ed
Location
Scotland
Hi guys, I am seeking some help...

I have a stage 2 GTI (MRC), ran the map for 35k miles +, no expenses have been spared with the car. Intake, Intercooler, Coils, Plugs, Sports Cat downpipe, Catback, engine mounts etc..... every precautionary step has been taken.

One night EPC light came on, misfire detected in cylinder one. Got the car recovered to a local VW specialist..... 5 weeks later injectors and plugs were switched and the car was fine. Picked the car up and first hill it started misfiring again!

Bought coil packs, and then bought NGK competition plugs. Car drove absolutely fine for 20/25 miles before it decided to misfire again. Still misfire in cylinder 1, there is a slight rattling sound coming from the engine too. I think it could be the timing chain, but I have hit a brick wall. There was a little bit of oil on the first plug, and it was toasted after 10 minutes before I swapped them for the upgraded NGK ones. I am already over £600 down, and my car is still off the road. The car will drive, but it is constantly misfiring, and is shaking. I am not sure if anybody can guide me in the right direction please :(
 
Hoon

Hoon

Autocross Champion
Location
Rhode Island
Your next step is a compression test.

This doesn't sound good at all. Do not spend another euro on parts until a compression test is done.

It's very easy to do, and in the US most auto parts stores will rent a compression test kit for free. Even if you have to buy one, they're not very expensive.
 
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saiifqadiir001

Passed Driver's Ed
Location
Scotland
A compression test has already been done, no loss of compression in any cylinders.

The thing that blows me away, is that whenever any of the plugs, or coils are switched; the car runs completely smooth until it decides to misfire again after a couple of miles :(
 
Jacobmk7

Jacobmk7

Go Kart Newbie
Location
NC
Car(s)
2015 GTI S 4dr DSG
When you pull the plugs do they have a bunch of oil on them?

Edit: I see you already said the first plug had oil on it, I would pull it out again after changing it and see if it has oil on it again already, to see if you have an oil burning issue that could be causing the plugs to foul out.
 
Last edited:
Hoon

Hoon

Autocross Champion
Location
Rhode Island
A single cylinder misfire typically isn't THAT hard to diagnose. If compression is good, you need spark, fuel, and because these engines have variable lift the solenoid that controls that needs to be working.

You know it's not plugs, coils or injectors... although you did mention oil on a plug which indicates a mechanical issue. I question whether it was actually oil if the car has perfect compression...could be dirty fuel from the cylinder not firing??

Next step is to verify that all of those items are receiving a proper signal from the ECU.

Also, the 8 solenoids sticking out of the head...if one of those dies you will lose a cylinder, so I would pull the 2 from Cyl 1 and swap with another cylinder to see if the misfire moves.
 
Jacobmk7

Jacobmk7

Go Kart Newbie
Location
NC
Car(s)
2015 GTI S 4dr DSG
Hoon said:
A single cylinder misfire typically isn't THAT hard to diagnose. If compression is good, you need spark, fuel, and because these engines have variable lift the solenoid that controls that needs to be working.

You know it's not plugs, coils or injectors... although you did mention oil on a plug which indicates a mechanical issue. I question whether it was actually oil if the car has perfect compression...could be dirty fuel from the cylinder not firing??

Next step is to verify that all of those items are receiving a proper signal from the ECU.

Also, the 8 solenoids sticking out of the head...if one of those dies you will lose a cylinder, so I would pull the 2 from Cyl 1 and swap with another cylinder to see if the misfire moves.
Click to expand...

I could be wrong on this but those solenoids I’m pretty sure only activate at about 3500rpm, they don’t don’t control cam phasing, (which I assume your talking about), all they do is slide the cam over to a higher profile, with more lift, for better air flow. The cam phasers which control valve overlap are on the side, by the oil cap.
 
Hoon

Hoon

Autocross Champion
Location
Rhode Island
Jacobmk7 said:
I could be wrong on this but those solenoids I’m pretty sure only activate at about 3500rpm, they don’t don’t control cam phasing, (which I assume your talking about), all they do is slide the cam over to a higher profile, with more lift, for better air flow. The cam phasers which control valve overlap are on the side, by the oil cap.
Click to expand...

Unplug one and you'll instantly lose a cylinder, even at idle.

They're doing something, all the time.
 
shortyb

shortyb

Autocross Newbie
Location
Upstate SC
Car(s)
Felon Taxi,Dad Wagon
Have you checked or changed the breather? May be malfunctioning and letting more oil into the intake stream causing the misfire. IIRC, cylinder one is closest to where the PCV is connected and may be why that one is getting oil fouled.
 
S

saiifqadiir001

Passed Driver's Ed
Location
Scotland
Hoon said:
A single cylinder misfire typically isn't THAT hard to diagnose. If compression is good, you need spark, fuel, and because these engines have variable lift the solenoid that controls that needs to be working.

You know it's not plugs, coils or injectors... although you did mention oil on a plug which indicates a mechanical issue. I question whether it was actually oil if the car has perfect compression...could be dirty fuel from the cylinder not firing??

Next step is to verify that all of those items are receiving a proper signal from the ECU.

Also, the 8 solenoids sticking out of the head...if one of those dies you will lose a cylinder, so I would pull the 2 from Cyl 1 and swap with another cylinder to see if the misfire moves.
Click to expand...

I do get the impression the car could be overfueling, and I do feel it is related to the ECU, it is booked in to the garage who done my remap on Monday. For a further inspection as I am limited with what I can do myself.

I don't know a massive amount in regards to the cylinders, but from what I have heard/read their are two different types of cylinders right? I am under the impression the previous garage replaced/checked one but not the other.

What confuses me the most, is that any adjustment to spark/coil/injector the run will run perfectly fine for a limited amount of time before misfiring again
 
S

saiifqadiir001

Passed Driver's Ed
Location
Scotland
Jacobmk7 said:
When you pull the plugs do they have a bunch of oil on them?

Edit: I see you already said the first plug had oil on it, I would pull it out again after changing it and see if it has oil on it again already, to see if you have an oil burning issue that could be causing the plugs to foul out.
Click to expand...

On cylinder one, there was a little on the threads of the spark plug
 
S

saiifqadiir001

Passed Driver's Ed
Location
Scotland
Shortybdub said:
Have you checked or changed the breather? May be malfunctioning and letting more oil into the intake stream causing the misfire. IIRC, cylinder one is closest to where the PCV is connected and may be why that one is getting oil fouled.
Click to expand...

If this is the issue, what do you reckon is causing the rattle in the engine. I feel it is connected to the ECU, causing the timing chain to act up
 
Twist1

Twist1

Autocross Newbie
Location
Breaking Mustang Hearts
You need to check voltage signals coming from ecu to coils. You more than likely have a computer issue or battery issue if leak down and compression test are positive and you replaced all the common causes.. good luck I know how frustrating misfires are on these damn cars...
 
S

saiifqadiir001

Passed Driver's Ed
Location
Scotland
Twist said:
You need to check voltage signals coming from ecu to coils. You more than likely have a computer issue or battery issue if leak down and compression test are positive and you replaced all the common causes.. good luck I know how frustrating misfires are on these damn cars...
Click to expand...

You are not wrong with the frustration :mad: I am booked in, to get a look at the computer issue. Car has been off the road for 5 weeks now, trying to find the time and patience :(
 
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saiifqadiir001

Passed Driver's Ed
Location
Scotland
***Update***

Timing chain issue has caused the engine oil to be covered in metal particles.... possibly the worst possible outcome. I need to either rebuild the engine or replace it. Going to go ahead and buy a second hand engine, and then trade the car in.

Selling the car was due to happen just as this happened. Just need to replace the engine first now which is depressing me. Just my luck....
 
Jacobmk7

Jacobmk7

Go Kart Newbie
Location
NC
Car(s)
2015 GTI S 4dr DSG
saiifqadiir001 said:
***Update***

Timing chain issue has caused the engine oil to be covered in metal particles.... possibly the worst possible outcome. I need to either rebuild the engine or replace it. Going to go ahead and buy a second hand engine, and then trade the car in.

Selling the car was due to happen just as this happened. Just need to replace the engine first now which is depressing me. Just my luck....
Click to expand...

Just curious, what was your build date?
 
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