307 2.0hdi misfire

[Andye007]

Hello all . I’m new to the forum and hope you can help. My wife 307 2.0hdi has a small misfire / hiccup when it’s cold. It ticks over lovely a smooth and revs ok. It’s fine when it’s warm. I have a code p1352 glow plug. I’ve changed the relay but haven’t had it code read since. Wouldn’t have thought glow plugs would cause a misfire as it starts fine.
Thanks in advance for any ideas etc.

[Christopher Robin]

A few of my VW techs tell me hdi engines don't rely on glow plugs to start them and to be honest you have no chance of changing them they are in the most stupid place. The most inaccessible place is the back of the engine under the windscreen, and guess what.... Yep that's where they are!
My wife's 2.0 hdi an 07 plate has been doing this for 5 years turn it over starts fine, ticks over fine, go to the it it misses and flanks and smokes(black) winter or summer, only on 1st start up after about 30 seconds of tick over its fine revs nice, last year it's turbo started to fail so we changed it and an ideal opportunity to change glow plugs and we got 3 out of 4 in, excellent we thought job done.
Still does the starting thing hmmmm back to drawing board late last year air temp sensor was changed made no difference to starting procedure. Back to drawing board!
Early this year the swine gave up completely in the fast lane of the A55 first dropping into limp mode then complete failure, wife had to coast from the outside lane into hard shoulder, not a happy bunny in rush hour, turns out it was crank position sensor 1st implusable signal then faliure, AA code read it to get that fault, I got there and it started and drive fine? Yet it had to be towed off express way.
We change crank sensor and she runs fine again took us a few days to realise hang on she is starting and running fine!
Coisandence... No idea
Was crank sensor causing this.... No idea
Let's wait until winter returns and we'll see how "fixed" she really is.
That is just my experience, but if you r thinking of changing your plugs ring up your local pub dealer and ask them how hard are they, mine told me the techs run a mile and that's probably why last owner sold it.... Thanks i thought.

[GiveMeABreak]

HDIs use high compression to ignite the fuel, and only need the glow plugs to assist starting in very cold weather. They also do help the engine to get to temperature more quickly on startup. They also perform other functions though; they assist in regeneration if your vehicle has a particle filter.

A lot of people with HDIs tend to leave them for as long as poss before doing them as they can be a pain to get out as you have noted!

[white exec]

On HDi, do the GPs also have a post-heating function? Under cold conditions (usually sensed by coolant temp) this can operate for several minutes after starting, but won't on subsequent (warm) restarts later in the day.

What is the compression ratio on HDi which can achieve a GP-less start?

[GiveMeABreak]

Yes Chris, Pre and Post Heating Function. In common with many HDi owners, I have the 'Glow Plugs not Supplied fault' which has been on the car since I've owned her and on the previous C5 II - never bothered with it and the car starts first time in all weather. When I get round to it, I will be testing the Glow Plug Relay to see if the message is one of the acknowledged ghost faults. But generally, these are the reference values, the operation is determined by ECU, but in the case of my Delphi System specifically:

Reference values for the pre-heating time (in seconds)

• A: Atmospheric pressure in hectoPascals
• B: Coolant fluid temperature in degrees Celsius

B	A	A	A	A	A	A	A
-	700 hPa	750 hPa	800 hPa	850 hPa	900 hPa	950 hPa	1000 hPa
-30 (°C)	30 s	30 s	30 s	30 s	30 s	30 s	30 s
-20 (°C)	20 s	20 s	20 s	20 s	20 s	20 s	20 s
-10 (°C)	15 s	15 s	15 s	15 s	15 s	15 s	15 s
0 (°C)	10 s	10 s	10 s	10 s	10 s	10 s	10 s
20 (°C)	10 s	10 s	10 s	10 s	10 s	10 s	10 s
30 (°C)	10 s	10 s	10 s	10 s	10 s	10 s	10 s
60 (°C)	7.5 s	7.5 s	7.5 s	7.5 s	7.5 s	7.5 s	7.5 s
80 (°C)	5 s	5 s	5 s	5 s	5 s	5 s	5 s

Reference values for postheating time (in seconds)

• A: Atmospheric pressure in hectoPascals
• B: Coolant fluid temperature in degrees Celsius

B	A	A	A	A	A	A	A
-	700 hPa	750 hPa	800 hPa	850 hPa	900 hPa	950 hPa	1000 hPa
-30 (°C)	180 s	180 s	180 s	180 s	180 s	180 s	180 s
-10 (°C)	180 s	180 s	180 s	180 s	180 s	180 s	180 s
0 (°C)	180 s	180 s	180 s	180 s	180 s	180 s	180 s
20 (°C)	180 s	180 s	180 s	180 s	180 s	180 s	180 s
40 (°C)	70 s	70 s	70 s	70 s	70 s	70 s	70 s
80 (°C)	0 s	0 s	0 s	0 s	0 s	0 s	0 s

Rail Pressures:

Engine speed (rpm)	Rail pressure ( bar)	Flow injected (In kg/h)
120	300	1.4
750	230	11
2000	1400	26.9
4000	1650	52.2

[white exec]

So Atm pressure (normal 1000mPa and down to a low 700) has no effect on heating time, it's just a function of coolant temp - which makes sense.
What is the compression ratio? Previous engines were up to around 23:1, iirc.

Could be that HDi manages to atomise the injected fuel so finely that it takes less chamber-air heat to ignite it.
A failure of just one GP on earlier engines (eg XUD) would produce really lumpy cold starting, but if HDi has this advantage, maybe faulty GPs (and relays) could be tolerated, except in very cold conditions.

Result of a test on a car with a flagged fault would be interesting.

[EDC5]

This is very interesting. My GP light stays on only for about 5 or so seconds in the cold from memory despite that table showing that it should be on for 10s. Maybe it's happy to start after 5s but will actually keep them energised for 10s.

I'm assuming the post heating is conducted at a lower power level otherwise the glow plugs would be burnt out pretty quickly?

[GiveMeABreak]

Sorry chaps, I'm painting the kitchen in between other jobs and catching up on the Brexit situation at present...

As for Postheating Elis:

The postheating starts as soon as the pre-heating phase is finished.
The pre-heating plugs are supplied without limit of power.
The length of activation of the plugs depends on the engine coolant temperature value, the atmospheric pressure (air density) as well as on the quantity of fuel injected (air temperature / fuel, air density).

The postheating stops in the following cases:

• The postheating time is exceeded
• The ideal value for the coolant temperature has been attained
• The value for the inlet air temperature is wrong
• The value for engine speed and load is too high

Postheating is used for limiting the emissions of hydrocarbons and carbon monoxide.
Postheating is used for loading the engine in order to bring the catalytic converter and/or the particle filter up to an optimal operating temperature as rapidly as possible.

Actions of postheating:

• Prolonging the operation of the pre-heater plugs after the starting phase
• Reducing the emissions of pollutants in the first few minutes after starting
• Reducing blue fumes especially at altitude

[GiveMeABreak]

What is the compression ratio? Previous engines were up to around 23:1, iirc.

Could be that HDi manages to atomise the injected fuel so finely that it takes less chamber-air heat to ignite it.
A failure of just one GP on earlier engines (eg XUD) would produce really lumpy cold starting, but if HDi has this advantage, maybe faulty GPs (and relays) could be tolerated, except in very cold conditions.

Result of a test on a car with a flagged fault would be interesting.

The actual compression ratio on my 2.0 HDi is 18:1, but it's the high pressure injection system in the HDi common rail system - with the third generation Delphi system providing 2000 Bar or 29007.55 PSi max pressure that can atomise the fuel so efficiently, along with the precise timing of the injection that really makes the difference, with multiple injection processes per cylinder, per combustion.

[EDC5]

I see, so that's why my economy is about 10-20 mpg lower for the first couple of mins when driving

Just a point about the Delphi injection system, if yours can go to 2000 bar and is the third generation injection it presumably uses piezoelectric injectors.

As far as I'm aware on my RHR its max working pressure is 1600Bar and uses solenoid injectors... Presumably I've got the second generation Delphi system?

[GiveMeABreak]

Couldn't say if they are solenoid or Piezo Elis - Bosch are typically 1350 (Gen 1) 1600 (Gen 2) & 2000+ (Gen 3) BAR respectively, with Denso Gen 1 at 1450 & Gen 2 at 1800+ and Delphi up to 2000. I know that in the early days, the French did stay with solenoid tech (whether fro penny pinching or not we don't know), but it's actually quite hard to find out the type of injector without trawling the cobwebs

[white exec]

This is very interesting. My GP light stays on only for about 5 or so seconds in the cold from memory despite that table showing that it should be on for 10s.

IIRC, the dash light goes out to signal to the driver that starting can be done successfully - but pre-heating will continue for a while afterwards (ie during starting). That would explain what seems like very short pre-heat times. Post-heating rumbles on after that.

[GiveMeABreak]

My pre-heater light doesn't stay on at all and goes off straight away with the other lights.

[white exec]

Some do. Probably signifies as more or less instant start is available - ie as long as it takes to turn the key. Our XM does just this, a lot of the time.

[EDC5]

Couldn't say if they are solenoid or Piezo Elis - Bosch are typically 1350 (Gen 1) 1600 (Gen 2) & 2000+ (Gen 3) BAR respectively, with Denso Gen 1 at 1450 & Gen 2 at 1800+ and Delphi up to 2000. I know that in the early days, the French did stay with solenoid tech (whether fro penny pinching or not we don't know), but it's actually quite hard to find out the type of injector without trawling the cobwebs

Fair enough, I just remember getting a historic code for the fuel pressure being over 1800 bar once, so obviously my system was one of the 1600 bar variants. I was curious that with your engine being the RHF engine that it has a better (2000 BAR) injection system?

My pre-heater light doesn't stay on at all and goes off straight away with the other lights.

I see mine for a split second this time of year, but in the depths of winter I've seen it on for a few seconds, probably about 5s.