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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 21602
Experience:  BEng hons Mech engineering, in auto industry 22 years
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VW Polo 1.4 TDI 80bhp (07 reg).I have been having

Resolved Question:

VW Polo 1.4 TDI 80bhp (07 reg). I have been having problems starting my Polo over the course of a year and have been struggling to get to the bottom of it. I've had the battery checked and this is fine with a sound level of charge. I've used a couple of fuel system flush solutions to clean it out to see if that solved the problem, the latest being microflex but the issue has persisted. It has come down to the starter motor as I realised it wasn't turning the crankshaft over efficiently. This has been replaced this week and after four days of non use, the car struggled to start this morning. After roughly 5 attempts the car finally started and subsequent attempts to start it were fine. You can hear the fuel lines being primed when the ignition is switched on but I am wondering if there is a air leak in the fuel system somewhere. I have had a smoke test carried out on it that resulted in no leakages being found. I would like to know if you have any advice on any other avenue I can explore as to solving this starting issue. Many thanks, ***** *****

Submitted: 2 years ago.
Category: Car
Expert:  Matt replied 2 years ago.
Hello

I'd check that you're getting full power to the glow-plugs, they pull a lot of current so take care when checking but see if the relay is clicking when the ignition is turned on first and also check the fuse if this is OK check to see if the engine earth strap is also OK.

If the plugs haven't been changed in the last 20K then they may have to be replaced.
You can test the glow-plugs with a multimeter by measuring the resistance across the plug ( between the power connection and the body) it should be around 4-8ohms if its tending to infinity / open circuit the plug is faulty or by using a clip on current clamp, either on the supply wire to glow plugs or onto engine earth, with glow plug light on you should see 15-20amps for each glow plug fitted, 4 cylinders would be approximately 60-80amps.

Also if its not injecting at all then check the connections to the crankshaft sensor, unplug it and check for corroded contacts and broken wiring, and consider fitting a new sensor - do the same for the cam position sensor
If the EGR valve is stuck open then this too can effect starting so try disconnecting it to see if this helps or changes anything

Could also be an injector leaking fuel back through the overspill pipe, so not getting enough fuel pressure to tell ECU to fire the injectors, this is trickier to find and you’ll need the garage to do a ‘run back’ test to identify which one is the issue
Lastly it’s also worth considering fitting a new fuel filter as if only slightly blocked this can lower fuel supply pressure and choke the main pump, the pump will be more sensitive to this when its cold as diesel thickens considerably with low temperatures.
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Customer: replied 2 years ago.

Hello Matt,

Many thanks for your reply. I am in the process of carrying out further investigation on the issue and am very grateful for your insight!

Regards,

Peter

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