02 C5 2.2 HDi - Glow plug light

[Vulpinity]

Random query here - how long should the glow plug light illuminate for on my 2002 C5 2.2 HDi?

Even when sub zero here lately, it barely even flickers on for a moment, and the car misfires like mad until slightly warmed up. No problems starting, it just runs rough as anything for a few seconds from cold!

Also starting to realise buying this to save money may be a bad idea, seeing as my average is hovering around 30mpg. I know it's an auto, but I was rather hoping for at least mid 30's, considering I don't drive much in town and rarely do trips of less than 10 miles across country.

[Citroenmad]

Ive never seen a C5s glow plug light stay on for more than a second or so, its only in the coldest of weather which it needs them. Above cold weather they are just not needed. Though you might have a failed/failing plug if your is misfiring or it could be something else.

30MPG seems pretty poor, im almost certain you would get only slightly less with a 3.0 V6 auto petrol! You might want to do a bit of looking into why its MPG is so low.

[CitroJim]

The HDi doesn't pre-heat until the brass monkeys are turning blue. There's a chart somewhere on here to show temperature vs. pre-heat and it's not until -a heck of a lot that they stay on longer than about a second.

However, the HDi will post-heat for a few minutes (i.e. light the glowplugs after the engine has started) from relatively mild temperatures. The light however does not illuminate during the post-heat phase...

I'll see if I can dig out the figures...

[CitroJim]

Here's the timings:

At a coolant temperature of:

-30°C pre-heating time 20s
-10°C pre-heating time 5s
0°C pre-heating time 0.5s
+18°C pre-heating time 0s


Here's the post heating data:

During the starting phase, the glow plugs are supplied under the following conditions :

• the coolant temperature is below 20 degrees C
• the engine runs at more than 70 rpm for 0.2 second(s)

POST HEATING

Post-heating consists of prolonging the operation of the glow plugs for a maximum of 60 seconds from the end of the starting phase .
Parameters which could interrupt post-heating :
• coolant temperature greater than 20 degrees C
• flow injected greater than 35 mm3
• engine speed above 2000 rpm

That's for the 2.0 HDi but I'd expect the 2.2HDi to be very similar..

So the lack of glowplugs could contribute to a bumpy start. Use a voltmeter on them to see if they are correctly post heating...

[spider]

Already present for quick reference > HDi Glowplugs - Indicator Operation

EDIT... Just re-read the topic properly this time.

[CitroJim]

Ahh, well done Andy I knew there was a thread around here but couldn't immediately find it. Glad that thread and my figures agree

30mpg seems very poor. That's more than likely the root of the problem. Injectors possibly as I've heard in the past they can cause ropey starting and rough running just after startup...

[Vulpinity]

I like this forum - Good information, delivered quickly!

I shall see if the plugs are all functioning, can't tell from the service history when they were last changed. Hope it's not injector problems, as I hear nightmare stories about getting them out of the head on the 2.2!

[Citroenmad]

Yes, ive heard they can be a total nightmare to remove on the 2.2, some requiring a new head! Though hopefully your won't come to that.

Depending on your cars mileage, the glow plugs could well be original.

Does your car have any injector rattle at lower revs?

[CitroJim]

Yes, ive heard they can be a total nightmare to remove on the 2.2, some requiring a new head!

I understand a can of Coke can work wonders for injector removal....

[Vulpinity]

Does your car have any injector rattle at lower revs?

Not sure exactly what injector rattle sounds like, but under load at lower RPM it does sound rather rattly from somewhere. Also seems to lack any real low end pull under about 1500rpm, but not sure what these engines are like, and coupled with the autobox it's never really going to like that rev range anyway.

Absolutely love the car, could just use a few more MPG out of it, because at the moment it's doing about the same average MPG as my old petrol BMW 328 used to. XD

[Vulpinity]

Quick update - Solved part of the MPG issue at least. Took it in to get the tracking checked, and the front wheels apparently were pointing rather substantially in opposite directions.

Feels much more responsive now and requires a lot less throttle to keep speed up. Felt like a slightly sticky brake before, now coasts along nicely when off throttle.

Might just replace the glow plugs as a precaution - any ideas on how hard they are to do? Done glow plugs on quite a few diesels in the past, but mostly rather old fashioned non-common rail jobbies.

[spider]

Ahh, well done Andy I knew there was a thread around here but couldn't immediately find it. Glad that thread and my figures agree

Yes, ive heard they can be a total nightmare to remove on the 2.2, some requiring a new head!

I understand a can of Coke can work wonders for injector removal....

I've heard that too, I think (if I remember correctly) its caused by water dripping onto them and 'sealing' them in with rust. Not all models suffer although a deflector is fitted to some models (people carriers maybe?) to prevent this. A massive repeated dose of PlusGas over a few days might help, not sure. Genuine 'Coke' (not supermarket copies) could work well too.

As a random thought: I was wondering the other day actually why the HDi injectors are clamped vs screwed in compared to an IDI unit, I thought about pressures but then again the actual compression / internal pressure in that cylinder is not that far different, unless the massively higher fuel pressure has a factor on it. I keep thinking I've overlooked something basic and obvious (as usual!) but nothing sprang to mind.

[CitroJim]

As a random thought: I was wondering the other day actually why the HDi injectors are clamped vs screwed in compared to an IDI unit, I thought about pressures but then again the actual compression / internal pressure in that cylinder is not that far different, unless the massively higher fuel pressure has a factor on it. I keep thinking I've overlooked something basic and obvious (as usual!) but nothing sprang to mind.

An interesting conundrum Andy. Pressures will be a little higher in an HDi than in an IDI engine but then the IDI injectors have some meaty old threads on them and threads are good at holding very high pressure back - look at Citroen spheres, they hold back up to 170 Bar with ease. Overall the pressures won't be that much greater overall and arguably the pre-chamber an IDI injector is screwed into most likely experiences greater instantaneous pressures than in a DI engine. Maybe that's why the majority of DI engines use clamps as the injectors don't have such pressure action on them so an economy can be made.

Also, DI injectors are a lot slimmer than IDI throttled pintle injectors so there's less area exposed for the pressures to act on.

In the end it all comes down to economy and ease/speed of assembly I expect. After all, it's a lot easier to push in an injector and then hold it in with a clamp than it is to screw in an injector to the correct torque.

It's a bit like the radiator bayonet connectors PSA experimented with in the mid 90s. Great for assembly but a right PITA whe it came to removing them. It's the same with push in and clamp injectors; easy in and bloody difficult out...

Odd the 2.0 8V HDi does not seem to suffer excessively from this issue despite using a similar sort of injector fitting...

[nick]

It puzzled me for years why some injectors were threaded and some were clamped but I think the answer is quite simple....Injectors where the fuel enters from the top are screw threaded, injectors where the fuel enters from the side are clamped.
Reason being if an injector with a side fuel inlet was screw threaded you have a hell of a job getting the torque on the injector thread exactly right AND getting the inlet port to line up with the fuel pipe properly. A bit like those garden water taps where you tighten the thread of the tap into the backplate perfectly, but then end up with a tap that points off to the side or up into the sky! You can pack a tap thread with PTFE tape to make the tap point in the direction you want, but you can't really do the same with an injector.

With a clamped injector you simply place the injector into the head with the inlet port lining up exactly with the fuel pipe, then tighten the clamp to the desired torque to hold it in place.

[CitroJim]

Nick, excellent I think you're absolutely correct whereas I just typed a whole load of waffle