Citroen C5 Glow Plugs

[Dommo]

Here's a post of mine on another thread. In this case my 2.2 173 HDi had a knackered starter which meant slow cranking and slow starts, new starter and it starts much faster every single time. I replaced the glow plugs after this job (3 were open circuit) and there was absolutely no difference - apart from when it's minus temperatures it started slightly smoother, but barely noticable.

So apparently the videos weren't on here. Here's the before and after, the temperatures were similarly cold and the battery is new.

http://vid180.photobucket.com/albums/x2 ... 4pd4eo.mp4

http://vid180.photobucket.com/albums/x2 ... wc45ix.mp4

[411514]

Haven't we been here before?

There does appear to be some confusion as to whether or not the HDi pre-heats. My understanding is that the HDi doesn't pre-heat but it does post-heat. In this respect bad glow plugs should not affect starting but might cause rough-running in the first minute or two after starting. I wonder if this lack of pre-heating is to make extra juice available for the starter motor.

[white exec]

There does appear to be some confusion as to whether or not the HDi pre-heats. My understanding is that the HDi doesn't pre-heat but it does post-heat.

If anyone has access to HDi service pages, that one should be easily answered.

[Dommo]

I have read this somewhere and it depends on both coolant temperature and outside temperature before it decides what afterglow timings to use - can't find it though at the moment!!

[411514]

I have read this somewhere and it depends on both coolant temperature and outside temperature before it decides what afterglow timings to use - can't find it though at the moment!!

Yes, that is true, the ECU does vary post-heat characteristics in dependence on coolant on ambient temperatures, but I understand that it does not pre-heat full stop irrespective of temperature. Maybe someone can confirm or rubbish this?

[ekjdm14]

Our 1.4HDi definitely pre-heats complete with a glow plug light on the dash, if the outside temperature (and presumably coolant temp, as it's stood overnight) is below +5c

I have heard a lot of people quoting a temperature of -5c for pre-heat on HDi but as said, the 1.4 at least definitely does it below +5c. Only for a second or so at that sort of temperature but longer the colder it is out. And yes, I have tried turning the key straight away and yes it does make a difference to cranking times. Only takes 3 or 4 sec to start on a straight turn but fires within half a second if allowing the light to go out first.

I've also seen a Citroen document posted on here not many months ago charting air/coolant temperatures and pre/post/regen heat cycle times for a 2.0HDi FAP.

So in conclusion, the HDi DOES use the GPs for pre-heating BUT not very often and it would likely still start eventually even if they were all dead (unlike the indirect XUD which needs good plugs for decent starting even in summer & refuses to start at all without them in cold weather).

Perhaps if somebody really wanted to gain some empirical evidence, they could substitute their HDi's coolant and outside air temp sensors with suitable resistors to tell the ECU it's something approaching -20c & then connect a voltmeter to the glowplug circuit and see what happens when they switch the ignition on...

[Dommo]

Here's something I found with relevance to the DW12TED4 engine, not the BTED which mine is but it still has some answers, see attachment.

Taken from page 109 of this document (page 99 from the numbers on the actual document, but 109 of the PDF)

http://citroeny.cz/navody/c5/System_Bos ... cky%20.pdf

[Dommo]

This is also quite interesting, demonstrates how short a time frame it takes to get up to full temperature with the 'new' design of afterglow capable plugs:

http://beru.federalmogul.com/en-gb/dies ... lugs-ge-gn

Presumably they run after startup to reduce smoke and to generally reduce the risk of DPF blockage on cold starts.

[mickeymoon]

I know my Berlingo doesn't use the glow plugs at all as they are all dead and have been for years.

Sent from my SM-G925F using Tapatalk

[Dommo]

I think you'll find it mainly affects the emissions control, apart from at very low temperatures where it relies on them like an old IDI engine. And I mean really really low temperatures.

[RichardW]

Only time I saw the glow plug light on my Xantia HDi was in Dec 2010 when it near to -20 - starting it then was like waiting for an old TD to pre-heat!

Not even sure the 307 / C4 has a glowplug light. Certainly never seen it, even at -10 starts.

[Hell Razor5543]

I know that my C5 has a glow plug light, as (in cold weather) I have seen it blink on for a moment.

[myglaren]

Haven't we been here before?

Several times.

[ekjdm14]

Haven't we been here before?

Several times.

All the more reason to get it cleared up once and for all I'd say... Now, who's going to volunteer to fool their car into thinking it's brass monkeys out & see what the GP's do? I'd do it myself but for the fact we don't have a 2.0HDi, and the 1.4 has been shown to use them below +5c anyhow...

Mickey, the GPs may be dead in your 'lingo but has it in fact been trying to use them to aid starting/cold running on freezing days?