Slow to start

[Ionise]

Hi, I have a 2003 Fiesta MK6 1.4tdci

In the last few months it has increasing took longer to start (now sometimes takes 4-5seconds to cold start).

When it does start normally there isnt that much smoke, just a little grey if anything (normal for a diesel thats 13years old)?
The battery has been tested okay and Ive been advised by a garage maybe the glowplugs but I dont want to end up in the endless loop of changing everything.

Any advice on what to try before changing everything? After start-up the car seems to run no problem, not sluggish or anything like that.
 

[isetta]

does the glowplug light come on? how long for?

are you in very cold climate?

does it help if you press clutch pedal all the way down when starting (it means gearbox oil which is thicker when colder is not causing drag on the engine).

Does starter motor sound slow in the few seconds it takes to start?

Engine oil also gets thicker when colder and causes more drag when starting - is there a chance it might have some thick cheap oil in there and not the proper spec stuff

 

 

[Tdci-Peter]

5 hours ago, Ionise said:

In the last few months it has increasing took longer to start (now sometimes takes 4-5seconds to cold start).

When it does start normally there isnt that much smoke, just a little grey if anything (normal for a diesel thats 13years old)?
The battery has been tested okay and Ive been advised by a garage maybe the glowplugs but I dont want to end up in the endless loop of changing everything.

I would put glowplugs quite a way down the list. High pressure common rail diesels start ok without glowplugs, in most normal UK weather. They may run rough for a while, but should fire up ok.

Slow cranking could be a problem. Bad starter motor solenoid, or worn starter motor, or corroded connections from battery to both engine earth & stater motor live can cause this. Especially if the engine is a bit worn, and down a little on compression. 200rpm is usually the recommended cranking speed. Some diagnostic systems (like Forscan) can measure this.

The other likely suspect is air leaking into the fuel system. Into the fuel filter, or into any of the pipes to / from the filter. (The HP pipes after the pump are not in this list, they would leak fuel out if there was a problem.)

A good non-return valve on the inlet side of the filter could cure un-locatable leaks. I fitted one to my system to aid priming.

Next I would check the fuel rail pressure. Again diagnostic systems can do this. It needs about 200Bar usually, just to operate the injectors.

[m1tch]

How many miles has the car done? Do you hear any 'chuffing' when the car is idling? When was the last time the fuel filter was changed etc.Might be an injector leaking off more than spec dropping the pressure to low on the fuel rail causing it to take longer to start.

[Ionise]

Never seen the coil light on the dash, I have heard TDCIs aren't reliant on the glowplugs eitherway

The fuel filter was changed less than a year ago, I dont know about the oil quality but the filter and oil was changed 6months ago by a garage.

I have an obd2 scanner somewhere but I cant find anywhere, that reads fuel pressure :/

Car has done 94,000 miles, no noticeable chuffing

Slow turnover is possible, whats the easiest way to test it? (can I disconnect something so that it wont start, but itll keep turning over and I could read the revs?)

[isetta]

re glow plug light. on my 1.6tdci i reckon I only saw it about 5 times each year (I had car for 9 years)  and never more than 2 seconds if that.

difficult to know what to disconnect on a diesel. on old petrol engines I just pulled the ht lead off the ignition coil.

Trouble is anything you disconnect might bugger something up or the ECU might sense the disconnection and stop the starter motor from being activated. it's all too complicated these days 

 

[m1tch]

10 hours ago, Ionise said:

Never seen the coil light on the dash, I have heard TDCIs aren't reliant on the glowplugs eitherway

The fuel filter was changed less than a year ago, I dont know about the oil quality but the filter and oil was changed 6months ago by a garage.

I have an obd2 scanner somewhere but I cant find anywhere, that reads fuel pressure :/

Car has done 94,000 miles, no noticeable chuffing

Slow turnover is possible, whats the easiest way to test it? (can I disconnect something so that it wont start, but itll keep turning over and I could read the revs?)

What is the battery like? Do you have a multi meter to check its fully charged etc? The cold weather will start to show up a weakened battery even though it will turn over fine most days.

Also, try starting the car with the clutch down, this will take a bit of load off the engine as the engine isn't attached directly to the gearbox full of thick cold gearbox oil - might not make a difference but worth a try.

[Tdci-Peter]

On 22/11/2016 at 8:40 PM, Ionise said:

Slow turnover is possible, whats the easiest way to test it? (can I disconnect something so that it wont start,

It is like Isetta says, not 100% easy. You could disconnect all the injectors, or disconnect the fuel pump IMV solenoid, or even remove the fuel pipe between filter & pump, but there are small risks with all of these. I am pretty sure you would get away with any one of those, but because the cost of any damage to injector parts or pcms is rather high, I would not be happy to recommend any without this warning. If the car was well broken, it would be a bit different, you could be rather more cavalier about it.

The safest way is to use the diagnostic facilities. Today I ran Forscan when I did a cold start on my car. Graphs are below. First time I have tried this!

The VCV is the valve (aka IMV) that controls the pump output pressure. It powered up just before the rpm showed a rise, presumably just as I turned the key to start position. The rpm rose to just over 200 (I think the steps in the graph are a result of the sampling time and resolution, not real). During this time the fuel rail pressure rose from 4Bar (390kPa) to about 200Bar (19350kPa). At this point the engine must have fired, and the rpm started to rise more rapidly.

The rpm varied about a bit after starting, my old heap sounds pretty rough after a cold (<10C) start, but that is probably pretty normal.

The 2 pictures are the same run, just with the "info bar" moved to display the readings. The time scale is seconds, showing about 0.6 sec from key to firing. I was impressed with that data, it tells quite a lot I think. It takes a bit of effort to get it, but none of it is any more technically demanding then plugging in a few bits, and clicking a few buttons.

 

(The white graphs do look clearer than the black ones)

Edited November 23, 2016 by Tdci-Peter
Turn Graphs White