[Engine] 1.6 HDi lumpy tickover when cold

[GraemeT]

Hi all
When first started in the morning our 1.6 HDi is very 'lumpy' at tick-over (if it was a petrol engine it'd be like no spark to one cylinder). Once warmed a little this goes away (before the temperature gauge starts to move even). No fault codes on the reader.

There's suggestions on the forum that a weak/broken glow plug may be a contributing factor.

I've attempted to find the errant cylinder by unplugging each injector in turn but that produces a similar result for each (engine gets lumpier) so no help there.

Any other suggestions before I start looking at glow plugs??

[geoff]

Air filter clean ?? Fuel filter clean ??

Try good dose of injector cleaner and monitor, try a tankfull of premium diesel.

Leave more exotic plans for afterwards - get a datum to begin with.

[jj9]

Why don't you test to see if you have a glow plug off !



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[GraemeT]

Hi JJ9 & Geoff

I think I'll need to bite the bullet and test the glow plugs (there I was hoping a 'wunder fix' would pop out of the woodwork) - we got the car in May and gave it new fuel/oil/air filters and a double dose of injector cleaner (I guess I could have primed the filter with a 50/50 cleaner/diesel mix but never thought of it).

I'll have a play with the plugs this weekend and report back if there's any success, to be honest it is not a huge problem at the moment but I'm thinking it may be come the winter)

Graeme

[polar]

The 1.6hdi can be a bit lumpy on start up especially if you only do short journeys mine can be exactly the same. You dont say how old or how many miles you have. By the way never unplug an injector and run the engine - very bad news!

[oilyrag]

To test the glow plug theory, assuming that one has not died completely. you can switch the ignition on and wait until the glow plug light goes out, or you hear the relay click, switch off, and repeat the process three or so times, without attempting to actually start the engine. This will get the glow plugs pretty hot, even the weaker one.
On the fourth go repeat the above but then turn the key to start the engine. If it starts more easily and runs better, then the glow plugs need changing.
I used to use the technique all of the time in winter, as it gives instant starting when really cold and helps a weak battery by not having to crank the engine over.

[jj9]

oilyrag,

The glow plugs on the 1.6 hdi only come on pre starting if the temperature is below a certain threshold (think it's approx 5 degrees) and even then it's only for a second or two.

After starting they stay on for a timed period of 3 minutes even in the summer.

A lumpy tick over after starting can be caused by defective glow plugs but this is very often overlooked because on direct injection diesel engines you don't need the assistance of the glow plugs to get the engine to start like you did with the indirect injection engines.


GraemeT,

My 1.6hdi had a lumpy tick over and slight misfire after starting which went away after 30 seconds or so (sounds just like your problem) . . . checked the glow plugs to find all four were knackered. Replaced the plugs and the problem was gone.

If you need to replace the glow plugs be aware that they are difficult to access and are easily snapped when being removed, you have to take it very slowly and gently with them, and make sure the engine is hot when removing them and make sure the socket stays square onto the plug, you don't want any lateral force on them.
They squeak and squeal as they come out like a partially seized bolt does.
Make sure to only apply the loosening pressure until the plug jerks a fraction, then relax the pressure before reapplying it.....and so on. They only move a little with each jerk so just go slow and steady and you will get them out.
Cover the body of the new plugs in anti seize grease before fitting.

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[oilyrag]

Ha! Worked on my 1.9D. so not the same! Apologies, but a lesson learned (by me!!) Thanks JJ9

[jj9]

Aye, I used to do the same on my old diesels, a double or treble heat on the cold mornings 

Modern diesels are a complicated beast compared to the older versions, you knew instantly if one of the glow plugs was off with an indirect diesel as it ran like a bag of hammers and smoked until the cylinder with the knackered plug warmed up..... simple times ehh   


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[geoff]

Modern diesels require a lot more LOVE .............................