Intermittent Misfire/Rough Running

[JTI]

Hi, hoping someone could help me with suggestions as to where I go with my car now.

TLDR Version:

Car switching between running rough and fine, have changed the following things so far. What to try next?

New set of coils
New spark plugs
Replaced camshaft adjustment valve
New fuel filter

Full Story:

For the past few weeks I've been having trouble with my car running rough. When it started it felt almost identical to when the coil packs went on my old car, but to start with I thought I'd try changing the spark plugs.

I did and the car then immediately ran fine for a week before it started running rough again. Upgraded the coil pack to R8 ones which made zero difference to the problem.

Noticed the camshaft adjustment valve looked like it was starting to melt so replaced that, but again this made no difference.

Took it to the garage who suggested it was the fuel injectors, and recommended someone local who could clean then. They also suggested trying system cleaner.

Tried some heavy duty system cleaner and then next day my car was running fine. Car ran fine for 3 days but still I took it to the local guy for injectors to be looked at. He said he'd tested the injectors first (not cleaned) and said they appear fine. Also the fuel filter was completely gunked up, including the pipes running to it (was original one from 2005!  ). Changed the filter and and car felt amazing, driving better than ever!

Then 2 days later it started misfiring again briefly, then was fine again. I thought it was just some gunk making it's way out of the system and thought nothing of it.

Unfortunately now, a few days later, it is switching between running fine and rough several times a day. For example it can drive fine for half an hour then suddenly start running rough while I'm driving. Judders like crazy when accelerating.

Was only showing a P0302 code originally but is now showing p0300, P0302 and P0303. Confused as to how it could run fine one minute, then terrible the next.

Any suggestions where I go from here with this in terms of things to check next? From reading on here a blocked catalyst converter, and problematic fuel pump have also been mentioned. Thanks.

[GVK]

P0300 is multiple cyl misfire
302 cyl 2
303 cyl 3

I read a lot of issues with these are injectors.

The guy thats 'tested' them perhaps was put off by the fact you have to remove the inlet manifold to access them?

[JTI]

^Yeah that's exactly right, which is why he just tested them (volt test on the injectors I believe).

Would they still work intermittently from what you've read?

Thanks.

[GVK]

I've had misfires on my ED30 which have been fixed with spark plugs / coils. I did have a high revs misfire with similar codes to what you have also had flashing MIL at those high revs (6k rpm+) a few months ago but weirdly it hasn't happened lately

I guess if they're (injectors) partially blocked it could cause your issues. I would get the injectors removed and tested properly at somewhere with an ASNU machine. (as shown on tr hamzas visit to r tech)

https://www.mk5golfgti.co.uk/forum/index.php/topic,121231.0.html

[Stig_gti]

I had misfire 6k+ replaced all injectors and cleaned carbon, problem still there ended up being a blocked catalyst converter. But I was down on power as well.

[ljc19630]

Sounds like injectors to me. Give R-Tech a call and I’m sure they will sort


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[JTI]

Thanks for the replies, it's going in Wednesday to have the injectors looked at and I've told them to check the cat also.

[ljc19630]

Good Stuff - I'm sure they will sort it for you. Let us know what the issue(s) were

[JTI]

Update (more headaches)- So car went into garage today with the intention of having the injectors cleaned. Car was running rough this time when it actually got to the garage.

Mechanic straight away checked the spark plugs and said they were black, and couldn't believe they were replaced about 3 weeks ago. I can't understand how they could get so gunked up in a short space of time. I asked would the system cleaner I used do this but he didn't think so.

Anyway he blasted the spark plugs clean, refitted them, cleared any codes and the car was running fine again.

When moving the car back to the forecourt for me to pick up the engine light came on again, and a different code appeared from nowhere which was p1531 (camshaft timing adjustment). Code was cleared but on the way home management light came on again.

Car is running perfect at this point but checked with my code reader at home and it now reported code p0010 (Camshaft Position Actuator).

Have had the car running on the drive for 5 mins and it sounds ok but I keep hearing little murmurs from the exhaust which I'm pretty sure aren't normal, however I'm over scrutinising every noise at this point.

So I'm not sure where to go from here. Am I looking at the camshaft position sensor next as I have already changed the camshaft adjustment valve? As it stands I'm pretty sure it will just gunk itself up again in a matter of days if I just leave it.

Thanks

[ljc19630]

Get it to R-Tech and I’m sure they will sort it. What’s the mileage of the car? Might not be related but has the Camshaft Follower that sits behind the Fuel pump been changed?


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[JTI]

Car's at 86k and cam follower is on my to do list. Actually have the part but was too difficult to do due to the banjo bolt, and there has always been a bigger problem with my car to fix first lol.

Think I may have solved the p0010/p1531 fault fingers crossed. Just checked the engine to see if anything obvious wrong and noticed the connector for the camshaft adjustment valve wasn't plugged in properly. The bit where you stick a screwdriver in to unplug the connection came off when I was changing this part and is now a little loose. Plugged back in and took car for a spin and no management lights so far touch wood.

But as to why my spark plugs gunked up so quickly is still a mystery. Will see how it runs over the next few days and will check the plugs over the weekend for any signs of anything.

[muff1991]

Car's at 86k and cam follower is on my to do list. Actually have the part but was too difficult to do due to the banjo bolt, and there has always been a bigger problem with my car to fix first lol.

Think I may have solved the p0010/p1531 fault fingers crossed. Just checked the engine to see if anything obvious wrong and noticed the connector for the camshaft adjustment valve wasn't plugged in properly. The bit where you stick a screwdriver in to unplug the connection came off when I was changing this part and is now a little loose. Plugged back in and took car for a spin and no management lights so far touch wood.

But as to why my spark plugs gunked up so quickly is still a mystery. Will see how it runs over the next few days and will check the plugs over the weekend for any signs of anything.

P0010 is definitely flagged up for having no connection to the VVT solenoid (cam adjuster solenoid) i had this so can confirm. you'll probably find the solenoid was buggered, you replaced but the connector was dodgy and it was flagging all sorts.. secure that plug so it doesn't come off and see how it goes mate.

[JTI]

Update - So I'm still having this issue and no idea where to go from here now.

After my last update, where the car had the spark plugs cleaned and I plugged the cam adjuster back in properly, the car ran fine for a day and a half. Then suddenly on the Friday it was running rough again. Had a look under the bonnet and under the coils and nothing obviously wrong. Put everything back together and car ran fine, for a week and a half even!

Then yesterday out of the blue I got a few little pops and jumps on acceleration but then it went back to normal. Today I did a 90 minute round trip, even in sport mode at times and it was fine. Then suddenly during a 5 min local trip it starts running rough as again. Been under the bonnet again and nothing obviously wrong. Had a look under the coils and can see a tiny bit of gunk around the bottom of where one of the spark plugs sits, but nothing that would be considered unusual.

I'll have a look at the spark plugs themselves over the weekend but I'm expecting they will be gunked up again as mechanic found last time.

So not sure where to go from here. Car does seem a bit laggy even when running 'fine'. I am wondering if it's an electrical problem? My mechanic seemed pretty certain it wasn't the fuel injectors, so don't want top spend around £300 cleaning them if it's not needed. O2 sensors? Diverter Valve?

[ady-gti]

Did you check for carbon build up on the intake valves?

[Sparkie90]

I would be inclined to change out the cam follower asap to rule that out and also change the PCV (relatively cheap) to rule that out.
Otherwise, were the new coil packs genuine VW, could there be a fault with them?
Mileage seems relatively low for injector issues but could be...