Computer says no

MIghtyG

ok, I think I know what the problem is but would love a second opinion/sense check on this.

Car info:

2014 VW Touareg RLine 3L V6 TDI 108K miles - service/oil change every 10K

The fault list:

Fault 1: Started developing a ticking/tapping noise when the engine was started from cold - this would go away as the engine got warmer. I suspected a hydraulic lifter but have also heard of injectors making this kind of noise.

No fault codes/warning lights on the dash.

I added a bottle of Wynns Formula Gold Diesel Treatment to see if it would do anything.

Fault 2: After a few days with the Wynns in the tank, the ticking seemed to be getting worse. At cold it was much louder and even when warm there was a faint knocking sound when the engine was at idle.

Fault 3: When on the dual carriage way, I went to overtake someone, put on a little gentle acceleration and the glow plug light started flashing (meaning fault with the engine management system), this was also coupled with a complete lack of power (limp home mode?) but I was still able to get up to around 60mph, albeit slowly and not uphill!

I managed to get off the dual carriage way and stop the engine. Starting again the fault was cleared and I managed to get back on the road. Again, some gentle acceleration on the dual carriage way and the light came on and I had no power. I got home and plugged in my OBD without stopping the engine this time.

P0087 - low fuel rail pressure.

Fault 4: Couple of days later I was taking the car to work (which is on the way to some local garages anyway) and I tried some gentle acceleration at around 50mph and again same problem as before. I restarted the engine which cleared the fault and tried some acceleration at 30mph and the car pulled away like a train.

Worrying about the Wynns I added I wanted to dilute the remainder in the tank so pulled in and topped the tank up (I had half a tank) wanting to treat the car I opted for VPower too.....

Car started no problem again and I managed to get heading to work, I let the road clear a little infront of me an tried some acceleration and it pulled like a train again, until it hit about 4000-4500rpm and the engine completely died. I managed to pull aside and could smell diesel strongly.

Lifted the bonnet and the it looks like the fuel return line from bank 1 has popped loose. Put this back on and thought it could be the filter getting clogged up due to the wynns treatment freeing up some sludge.

Replaced the fuel filter and tried taking the car for a drive. Managed about town no problem and could get up to 70mph ok but again, hard acceleration up to 4000-4500rpm killed the engine and blew off the fuel return line from bank 1. but this time I noticed the knocking got worse when the hose blew off so I started thinking the knocking and my fuel problem are one and the same.

By this point my mechanics stethoscope had arrived so I started having a prod about the engine to have a listen. On the rocker cover on banks 1 and 2 you can hear faint knocking, nothing that (to me) sounds bad. I then wen injector by injector and you can hear the ticking of the injectors and they all sound the same until you get to cylinder 3 on bank 1. Sounds like someone is beating the injector with a hammer.

so, could all this be getting caused by a failing injector? My guessing at the moment is the valve is leaking and fuel is blowing past the injector and dumping in the return line. 1, causing the low fuel rail pressure and 2, causing the return line to over pressurise and pop off.

thoughts/opinions?

gibbo52

Change the injector then get a job in a garage.

car-man

Sounds like it could be a fuel rail pressure regulator or sensor fault.
I would have the fuel rail pressure checked.
If you want confirmation of an injector fault then you need to do a leak off test which involves removing the return lines on each injector on the bank that is giving trouble, but preferably all injectors, then fit pipes to each injector. Have some plastic cups or glass jars then fit the pipes into the cups/jars, you may need a proper kit for your car ...run the engine and check the level of each cup/jar...they should be even...the alleged faulty one will be different than the others.
Another check is to put the car on a diagnostic machine (a proper one, not a code reader) and run the engine to do an injector value test and a fuel pressure system test.

Personally, the first thing I would do is to have a proper diagnostic check done by someone with proper diagnostic kit which includes a fuel pressure test and injector value check.
Another test for the injector is to swap it with another cylinder's injector and see if the fault follows the injector swap.

MIghtyG

Thanks car-man, have been reading up on an injector test and it looks relatively straightforward so might do this at the weekend if the weather holds up.

One other thing I was thinking about doing but havent yet - if I simply unplug the injector and run the engine and the tapping sound goes away, would this indicate the fault is on the injector?

Only reason I havent don it yet....is it safe to unplug an injector from the engine?

My plan was to unplug Cylinder 3, start the engine (or at least turn it over) then stop the engine and plug it back in. Repeat for cylinders 1-6 and see if I can narrow it down to the injector on cylinder 3.

gibbo52

I wouldn't piss about anymore, especially if you're paying out for diagnostics, find out how much an injector is and if it's not a mortgage price then get one and bang it in.
Your diagnosis is as good as any "proper" diagnostic machine if not better.

MIghtyG

Its not a 5min job - the positioning of the injector means I need to remove the air intake box. Plus I dont have a VAGCOM to do re-code the injector after installation, aaaand the injector is £300. If it was less than £100 I would take a punt but id rather spend a bit of time making sure the right part is fixed vs. throwing money at it.

So far my total outlay has been £15 for a bottle of fuel additive and £30 for a fuel filter. £0 for diagnostics. I have a second car so no rush to get this fixed yet.

car-man

A code read didn't show a faulty injector only a low fuel rail pressure code (which could mean one of several things)... A "proper" diagnostic session with a diagnostic machine will show you live data, showing what each injector is doing and what the fuel pressure is showing from all parameters and at different revs.
The fuel rail has a pressure regulator and a pressure sensor plus a metering device...all of these need to be checked to see what is happening...just "banging in" a new injector sounds cool, but what happens if something else caused the failure should there be an injector failure?
As I said, there hasn't been a fault code for a faulty injector!

Before you replace a part, especially an expensive one, you need to be 100% certain that the part you are replacing is the one that is faulty, plus you need to know if there is a fault elsewhere in the system that caused that failure...proper diagnostics!!

car-man

You can unplug the wiring connector from the injector and see what happens, but NEVER undo the injector to see the fuel flow...that is extremely dangerous!
You may get a fault code for a faulty injector.

Delvey

Why not have a look here and see if any of our local friendly members could help
AVForums car diagnostics - members who can help. VCDS and other tools.

Aerojon

Just hope it's not the HPFP..