Compression test - how to disable fuel pump. etc?

[LesPaul]

Greetings!

Happy to have found a dedicated Scirocco forum… I’ll get straight to the point!

TLDR: Which fuel pump fuses/relays should I remove while doing a compression test?

Detail:
Our 2014 2.0L R line TSI Scirocco (factory standard - unmapped) w only 116k miles recently died on us while on motorway. The Engine symbol (“catalytic”) light came in (but not the EPC light) and car lost power where we managed to coast to an exit. Engine then died and wouldn’t restart - it sounded like it was “trying” to start/sputter, but it didn’t “catch”.... So we called roadside assist and had it towed to a main dealer.

I was convinced this was going to be an ign coil issue as when a coil pack went about a year ago, the symptoms were similar (except then the EPC light came on without the cat light), but the car was still driveable. The mechanic at the time only replaced one coil, so I thought the other 3 couldn’t be too far behind and that another of them may now have gone.

However, after a “basic diagnostic”, the dealer said that cyl 3 was “full of oil”. On a later phone call they also said there was water in it, but that as there is no EPC light or codes stored that it’s not the coils and that to troubleshoot further they’ll need to spend another 4 or 5 hrs taking the engine apart (about £1100!). BTW, cyl 3 was the same cylinder where the coil had been replaced about a year prior…

Not happy with that and not being able to talk directly to a mechanic I had the car towed “home” where it now starts, but is rough as hell - and no error lights. It’s definitely misfiring on at least one cylinder…

I removed the spark plug from cyl 3. It was sooty, but not oily. (I need a larger wrench which I don’t have at the moment to remove the other plugs which are tighter). I didn’t see any signs of water, and both the coolant and engine oil look normal and show no signs of mixing. In short, I’m not convinced of what the dealer told me and amn’t ready to write off this car yet without some more homework.. Per title of this post I want to do a compression test - but have read in several places to remove the high pressure fuel pump relay and / or fuses before doing so.

So my question is, which fuses/relays to remove and where are they?

Also.. I removed each of the coil packs and measured resistance. I noticed that the replaced one (i.e. from the “failed” sooty plug cylinder (3) measures 77k which is significantly lower than the original VW Stock ones that each measure about 97k. I’m not sure if that means the “new” coil has failed or if it was always like that - it doesn’t look like a genuine VW part (has “VMQ” on it), has no covering on the “shaft” and weighs a bit less than the others…

If the compression tests are OK, I’ll spend some money on a new coil to test things. I’m just wondering if anyone had an opinion on the different resistances or on this non-vw replacement coil that was running in the now apparently faulty cyl 3…

Tks!

[bigkris06]

You don’t need to disable the fuel pump to do the compression test, just disconnect the coil packs to stop it from firing, the amount of fuel (if any as the ecu may detect the coils have been disconnected) will be minimal and not cause any issue.
If when you look inside can’t see any oil then they may be wrong. Another garage / mechanic may be able to give you further information.
I’m not sure the coil pack is going to be the issue though because you should get a misfire detected fault code but it may not be there straight away if the first garage cleared all the previous codes.
May be worth checking codes again once car has been running a couple of times as it may have picked up a code. If it does and state’s misfire on cylinder x, swap that coil to another position rerun the car and repeat the test, if the fault moves, then the coil is at fault. If it stays the same then the fault will be somewhere on that cylinder.
If you have any further information, please feel free to share and we may be able to help you further.

[LesPaul]

..just an update for anyone who’s curious. I ordered a compression test kit along w a proper plug wrench.

I needn’t have bothered w the compression kit because the plug in cyl2 was completely SMASHED! As can be seen from the photos I (hopefully) attached, the plug earth tip was bent up into the plug body and the ceramic centre electrode was also smashed. I did a compression test anyway but there was nothing. I also dropped an endo cam into the cylinder and saw lumps (and lots of carbon) on the top of the piston.

If I had garage space I’d investigate more myself, but I don’t, so sadly the car is now basically a write-off.

Dealer serviced, 116k miles, never driven “hard”. This shouldn’t have happened….

[bigkris06]

That looks as though it has been hit by something?
How long have you had the car? Don’t suppose you have any warranty?

[LesPaul]

..2nd owner.. owned car for 9 years, always dealer serviced according to schedule. no warranty… Looking back on past MOTs I noticed that the idle CO and idle HC numbers were massively increased on the last test. Car still drove OK though, but that obviously was the first signs of impending doom…

Annoyed that something this catastrophic happened to a properly maintained car at just 116k…

[bigkris06]

I’m sorry to hear that. I think it’s just a case of bad luck as Like you say you have kept the servicing up and looked after the car. If the car passed mot on emissions I don’t think there would be any reason to draw you to it, I’ve never even looked at the emissions sheet unless it failed.
Are you looking into repairing the car or replacing?

[LesPaul]

…repair not feasible. Its just sitting in driveway waiting on me to get act together to sell it as a non-runner!

[bigkris06]

So sorry to hear that
May I suggest breaking it I you have the off road storage? Parts always sell well and you get back substantially more than selling for spares or repairs… I was getting prices for £400 for a bonnet alone on mine!

[LesPaul]

Good (and enlightening - £400 for a bonnet!) suggestion, but there’s unfortunately no space for that

[bigkris06]

I remember a couple of years ago when my son and I broke an Audi A1 (as it worked out cheaper than buying parts for a salvage car)
She only lost the drive for a couple of weeks but she hit the roof .
It should still fetch a reasonable amount even being sold as spares or repair obviously depending on spec, age and condition. There is a couple of people that but them purely to break but on the other hand, someone may buy and repair it.
Have a look on eBay, put in your model and year (scirocco spares or repair) and you may get a rough idea of what’s it’s worth.
Sorry we haven't been able to help you get it back on the road but hopefully you’ll get a decent amount to put towards the next car.

[LesPaul]

..Thanks all,

Well.. It’s gone to Scirocco Heaven (or so ‘d like to think!). I’m sure it was fixable - and feasible to do so, but having no sheltered space, heavier tools etc. and it taking up space in the driveway it just made more sense to have her taken away… Quite sad to see it disappear on the back of a flatbed after all the years pleasure it gave…

Sayonara Scirocco!

[bigkris06]

What’s the plan moving forward? Another scirocco?

[LesPaul]

…sorry for late responses - for some reason I don’t get notified of new posts!

It was girlfriend's car and she would have loved another Scirocco if VW still made them - or something like them. Ended up with something far more “sensible” (and economical !)

[bigkris06]

Something sensible and economical? How unfortunate lol. Sorry you couldn’t sort your Roc.