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Matt
Matt, Mechanical Engineer
Category: Volkswagen
Satisfied Customers: 20591
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Jetta turbo diesel. Starts ok but looses revs and cuts out

Customer Question

Jetta turbo diesel. Starts ok but looses revs and cuts out worse when it's colder conditions and came take up to three tries to catch the revs. No warning lights on dash and nothing on diagnostics.
It has new glow plugs at its recent service.
Suggestion is wiring to glow plugs or immobiliser problem.
Alan Mills
Submitted: 7 months ago.
Category: Volkswagen
Expert:  Shantal-Mod replied 7 months ago.
Hello Alan,
I'm Shantal and I'm a moderator for this topic.
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I was checking to see if you had already found your answer or if you still need assistance from one of the Professionals.
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Shantal
Expert:  Matt replied 7 months ago.
HelloI'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 sensorIf 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 issueLastly 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.
Expert:  Matt replied 6 months ago.
Hido you still need help?Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

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