I feel my car is not being as fuel efficient as it should be, I know the Damaged MAF wiring loom is not helping and I have ordered some wiring that will arrive next week and it should improve my fuel economy, but I am wondering also  about the glow plugs

 

My car has a full service book but I have discovered so many dodgy things about my car that I am not sure this is true. for example my friend said it took him several hours to take off it was either the oil or fuel filter, if my car had been serviced recently as said then surely the filter would not have seized on like it did 

 

So I am wondering, should I replaced my glow plugs, reason's I suspect they might be faulty is.

. car sometimes turns over for too long until starts up the engine ( only when cold and not always )

. Car not as good on fuel as it should be going by the written statistics for my car

.engine chugs sometimes but not always, this is when not at full operating temp, only chugs on idle.

 

We took each glow plug out a few weeks ago and each one glowed fine when tested, but shortly afterward I realized my car turns over for a few seconds longer than usual until it starts only when it is cold, this does not always happen though.

 

 

So should I replace glow plugs ? 

Does the glowplug light show up for an extended length of time?

In cold weather they usually stay on longer and you should always wait until the light goes out before starting a diesel engine.