MK5 GTi - Power delivery issue after injector replacement

[Tim94]

Hello,

I've got a 2007, 135k MK5 Gti DSG (BWA) which was recently suffering from a cylinder 2 misfire during cold start/low rpm. I opted to replace the single fuel injector with a used low mileage part to save on cost, I did the work myself so didn't have to worry about the potential of it not working and then having to repeat the job (no labour costs).

I completed everything on Saturday, took me the best part of the day as I also cleaned out the intake valves, manifold and other 3 injectors. This may be a critical error but I did not replace any of the seals as they all looked fine after a good clean, I did also lubricate the top injector seals that go into the fuel rail. It looked like the manifold had been off before as a few things were marked up. As far as I can tell everything went back together fine and the car started up after I primed the fuel lines a few times, it was lumpy for the first few seconds but then smoothed out and the misfire had gone away. I was feeling pretty pleased at this point..

On Sunday I took the car out for a quick test drive, took it steady for the first 15 minutes (less that 50% throttle) and everything seemed to be in order. I did notice that the car took a little longer to start that normal but just put that down to the work that had been done and hoped that it would clear up with a run in. On my way back I decided to get on the power some more, applied around 80% throttle and the engine immediately dropped all revs and pretty much died, I backed off the throttle out of panic and then shut it off. I restarted the car and it seemed to fire up and run normally again so continued at a slow pace. I found a suitable spot and went WOT, the revs shot up to around 5k, began to pull and then it dropped back to 1/2k as if someone had stamped on the brakes. This time I kept my foot down and it then bounced back to 5k and repeated the same over and over, I noticed a load of black smoke out of the rear window and then backed off the throttle to around 40% where I was able to keep it going.

I did some more runs and it seems that whenever you get upto 4/5k it starts to cut out. I did also have it happen at lower rpm when traveling at a higher speed (60mph+). When stationary I am able to put the car into neutral and rev it to redline without issue.

Scanned the car with a generic OBD reader and found the following codes:

• P2293 - Fuel pressure regulator 2 - Performance problem
• 12555 - Low fuel pressure/Fuel pressure of out tolerance
• 0135 - Recirculation flap motor - short to ground (this may be unrelated but wanted to share anyway)

I have tried clearing them and going for another drive but it just comes back. It was pretty late by this point but I did have a quick look in the engine bay to see if anything looked untoward but nothing jumped out at me. I will try and have a better look later on today but any suggestions would be great.

One other thing to note is that the cam follower was changed within the last 10k miles so I don't think that could be at fault (I saw it mentioned on a few similar threads).

Thanks,

[JoshB]

It's definitely a fuel starvation problem. Could be something as simple as a sensor.
Go over all the wiring you disturbed and make sure all the contacts are clean and they are all secured tightly/clipped in properly.

Could be something as serious as a new fuel pump...

[FJB]

I would take the manifold off again and check all the wiring and replace the seals. The seals are available as a kit from Mr Injector, search on eBay for: Viton Seal & Bush Set For Bosch 0261500 Series Petrol Fuel Injectors - Kit 115. You will need a tool to replace the teflon seals.

[pudding]

Yep, the teflon seals are one time use only. 

[Tim94]

Thanks for the responses guys. Hopefully I'm not speaking too soon but the issue seems to have gone away. Since driving the car home on Monday night I noticed that it was no longer cutting out at all. I have since given it a few hard runs without any issues so fingers crossed it was some kind of contamination in the fuel line/pump.

If the issue returns I will replace the seals as a first port of call.

Thanks again.