nicholasbc

I’ve had about 4 trips to the dealer for the check engine light, on my 2010 Q7, (120k miles). Various parts were changed under the fix warranty, some more than once!:catalyst, AdBlue injector nozzle, oxygen sensor.
now the check engine light is off, but I don’t think my glow plugs are being energized long enough for easy winter starting. The manual says the operation of the glow plugs is a function of air temperature, so I now cycle the plugs with the key, before engaging the starter motor.
Is this controlled by the engine management computer, which may have been misprogrammed by the “FIX”? The plugs have been checked for continuity, and are all 1-2 ohms resistance.
My Mercedes GL 320 diesel has no trouble starting in the same temperatures.—Nicholas

dreadlocks

How cold is it? if its near zero I often cycle the plugs once or twice too.. I doubt the fix fiddled with the maximum dwell time of the plugs.

nicholasbc

thanks for your reply!
in this case only about 15 degrees, so I am wondering how easy starting will be at our design day temp of 0 degrees!
Can the glow plugs lose their effectiveness, even though the electrical test is within specs?—Nicholas

Greg5OH

^dont think so, as the resistance would have to change, or go to full open if burned out

dreadlocks

you got access to a VCDS? There are plenty of faults that can be triggered and stored but wont trigger a CEL or any other indicators... there are also access to sensor outputs so you can check them out and see if they are giving sane numbers.

Devovino

Out of curiosity, is there a plug in for these vehicles for either A) trickle charge the battery B) pre warm the oil/engine block like a lot of diesel trucks do?

Like states above, sometime it helps to cycle to glow plugs twice to facilitate cold weather starts in the absence of a block heater.

dreadlocks

only aftermarket solutions, in northern europe you could get a diesel parking heater from the factory but it was never offered in North America and there was nothing to plugin.

Justin Perkins

With a good battery and properly functioning glow system, your engine should need no assistance starting in any of the typical winter temps we have in NA. I can't say for sure on sub-zero (Fº) temps, but living in Vermont and now Michigan, I've never had an issue. Started right up (glow light was out after about 1s) this AM at 10º and hit the road like a normal day no worries.

(2014 TDI 70k miles)

dreadlocks

push button start will dwell the glow plugs properly if you do it right, I dont even pay any attention to the glow plug light anymore and it starts right up.. Ive fired it up at -15F w/mebe a few extra cranks and that was it.. my 2.0L TDI I got going at -25F w/out any assistance but it sounded like hell for a lil bit, after cycling the plugs twice.