Fabia 1.9TDI Strange engine startup issue

[Flipty]

Hi,

 

I've been the proud owner of a 2002 Fabia Mk 1 1.9TDI PD (ATD Engine) 100bhp comfort estate for about 4 years. 

It's recently developed an engine issue on startup, when left for a number of hours (usually overnight or for a long period in the day) it will start, then after around 3-4 seconds it will start to "chug" and struggle. The revs will drop and come back up again to normal. It does this for around 20 seconds, then the revs come back to their normal level and the revs then become stable. As the revs are unstable the car emits a bluish smoke for a few seconds also, but this stops when the problem stops and it doesn't do it while the car is running normally. My last oil filter, fuel filter, air filter and oil change was 6 months ago and didn't coincide with this issue.

 

Its a hard problem to describe so I took a video to show the issue and uploaded it to Youtube:  https://www.youtube.com/watch?v=Er2sjVbakDo

 

I've been trying to diagnose the problem myself, I've checked the glow plugs with a multi-meter and they are showing no resistance problems. The next thing I'm going to try is to clean the EGR valve.

 

Any advice on what the issue might be would be a massive help, thanks.

[sepulchrave]

Change the ECT sensor first, these do give trouble after a while.

[Flipty]

10 hours ago, sepulchrave said:

Change the ECT sensor first, these do give trouble after a while.

 

Thanks sepulchrave. Good shout, I'd read that was another good replacement to try and fix this issue, my only problem was I can't seem to disconnect the clip covering the ECT sensor (maybe it's even the wrong thing). Tried to find info on the net or a video of how to do it and couldn't. I need to find it in the haynes manual but im struggling to find it there too

[Tech1e]

The electrical connector needs the tab rocking back which will lift the internal tag to release.

 

Have you replaced the fuel filter recently? The return valve on the top can can these sorts of issues, might be worth replacing that.

 

After that you are into diagnostics and reading live data with VCDS rather than warming up the parts cannon.

[Flipty]

1 hour ago, Tech1e said:

The electrical connector needs the tab rocking back which will lift the internal tag to release.

 

Have you replaced the fuel filter recently? The return valve on the top can can these sorts of issues, might be worth replacing that.

 

After that you are into diagnostics and reading live data with VCDS rather than warming up the parts cannon.

 

Thanks for the input Tech1e. I did replace the fuel filter around 6 months ago, it didn't coincide with the engine issue but I will definitely look at the return valve like you suggested.

 

I'll also try and replace the ECT and see if that makes a difference. Other than that I can get pay someone to come and use the VCDS on my car and get the fault codes. (I tried a ODB Bluetooth connector on eBay but I couldn't get it to connect, then I tried to setup the ross-tech software but they charge extra for pre-2007 models I think. So I might just pay someone to give me a print out)

 

Any other advice appreciated!

[Flipty]

Started it today and it stalled on startup and engine cut out. I tried to start it again and it just made it through the chugging stage (as shown in the above video). I then drove to the supermarket and spent 30mins shopping. Came out and started it and it started with no issues whatsoever. So it does need a long period or overnight to develop this issue.

[maccy]

Looks like the fuel running back problem.

[Flipty]

50 minutes ago, maccy said:

Looks like the fuel running back problem.

Thanks for the input maccy. What should I look at replacing in your opinion. Someone suggested the valve on the top of the fuel filter? Or something else?

 

[maccy]

The valve on top of the fuel filter is an option,although I always thought it was a pressure regulator.Another option is a non-return valve in the line into the filter head to stop fuel creeping back to the tank overnight,but that does not cure the base problem.Somewhere in the fuel system something is letting air into the pipe work which then lets fuel run back towards the tank creating a bubble of air in the lines.When you start after a long period of standing  the car fires instantly with the fuel in the system,as soon as it starts it pulls the air in and misfires and splutters to keep going.A way to try to get around this maybe would be to turn the ignition on and off a few times to let the pump in the tank flush out the air.I personally would be looking at fitting new fuel pipe clips everywhere to stop any fuel run back.Good luck,let us know how you get on.

               PS.It won’t be a glow plug problem as it is too warm to even need them at the present time.

[Flipty]

Thanks so much for your advice maccy. What you suggest seems to fit with the problem. I am definitely going to look into it as my first priority and let you know how I get on.