C5 stuck in idle

Ralfie · Post by **Ralfie** » 23 Mar 2010, 16:04

2005 Citroen C5 Exclusive 2.2 diesel.

If the car is left at idle rpm for a while, it will just stay in idle and will not respond to any throttle demands. But if you turn the ignition off and on, it will reset and respond normally.

The dealer says that fuel pressure in the injectors lowers more than normal when it gets stuck in idle, but having replaced most of the fuel system, at great cost, it still happens.

When on the road it runs well, but occasionally a slight 'hunting' to the engine (barely perceptable).

Another thread mentioned cleaning the MAF sensor for idle problems. Where is that sensor? The dealer mentioned air in the fuel line, but ran checks on the line and found no leaks, and another C5 he had also had air bubbles in the fuel line (and no idle problem).

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KevMayer · Post by **KevMayer** » 23 Mar 2010, 17:47

The MAF fits in line with the air filter box. It's a sensor which measures how much air is entering the engine. The ECU then works out how much fuel to inject. The MAF measures air flow and air temperature.

Some say a MAF is only good for 50k miles, so, it may be worth trying a new one.

You need one of these. I've just fitted on to my 2.2 Hdi:-

http://cgi.ebay.co.uk/Air-flow-mass-met ... 414860b9ab

A faulty MAF gives poor power and rough tickover problems.

Go for it, they're cheap enough

Ralfie · Post by **Ralfie** » 23 Mar 2010, 18:33

KevMayer wrote:
Some say a MAF is only good for 50k miles, so, it may be worth trying a new one.

Thanks for that. I will check if that part number matches (or are they all the same) and invest. It looks like a simple enough swap.

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cachaciero · Post by **cachaciero** » 23 Mar 2010, 20:01

I doubt that a new MAF will cure this particular problem. From personal experience if you take the piece of rubber pipe that connects to the MAF of so that the engine is breathing through an open pipe and the MAF does not see the airflow, the engine will start it will idle it will pick up AND the engine managment light will come on and the engine not unreasonably goes into LIMP mode BUT the point is the simulated failure of the MAF does not prevent the engine from picking up from idle.

As I keep on saying get it on a Lexia and have a look at the engine parameters, as has been proved by the statement that "most of the fuel system has been changed" changing things without doing some analysis first is an expensive way of trouble shooting, half the cost of the fuel system would have paid for a Lexia.

cachaciero

Ralfie · Post by **Ralfie** » 15 Apr 2010, 16:27

cachaciero wrote:
As I keep on saying get it on a Lexia and have a look at the engine parameters, as has been proved by the statement that "most of the fuel system has been changed" changing things without doing some analysis first is an expensive way of trouble shooting, half the cost of the fuel system would have paid for a Lexia.

cachaciero

Thanks, but the dealer had it on their system many times, and to no avail. Among other things, they came up with:

P1198 high fuel pressure
P0087 high fuel pressure (pressure too low)
U1118 no communication with bsi airco
P1693 switching engine on/off
S7345 unknown code
P2563 wastegate position unexpected

After ringing every dealer and Citroen specialist in Europe, they came to no conclusions (and no cure).

Thanks anyway,

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cachaciero · Post by **cachaciero** » 16 Apr 2010, 22:11

Ralfie wrote:
cachaciero wrote:
As I keep on saying get it on a Lexia and have a look at the engine parameters, as has been proved by the statement that "most of the fuel system has been changed" changing things without doing some analysis first is an expensive way of trouble shooting, half the cost of the fuel system would have paid for a Lexia.

cachaciero

Thanks, but the dealer had it on their system many times, and to no avail. Among other things, they came up with:

P1198 high fuel pressure
P0087 high fuel pressure (pressure too low)
U1118 no communication with bsi airco
P1693 switching engine on/off
S7345 unknown code
P2563 wastegate position unexpected

After ringing every dealer and Citroen specialist in Europe, they came to no conclusions (and no cure).

Well all those codes tell you something but do you know when the codes were posted? what has been done about curing them one by one fuel rail pressure has it been checked? lack of comms BSI to Aircond? Waste Gate?

I suggest that you do the following find a dealer with a Lexia then:-
Read the current error codes.
The codes should be noted and then cleared.
Then the car should be started and run to reproduce the problem, then the error codes interrogated and then using the parameter pages check values associated with the error codes e.g what the values of things like the fuel rail pressure actually are this can be done from a Lexia but many cheaper general purpose analyser will only read the fault codes which on their own don't always tell you too much.

cachaciero

Ralfie · Post by **Ralfie** » 17 Apr 2010, 09:05

cachaciero wrote:
Ralfie wrote:
P1198 high fuel pressure
P0087 high fuel pressure (pressure too low)
U1118 no communication with bsi airco
P1693 switching engine on/off
S7345 unknown code
P2563 wastegate position unexpected

.
Well all those codes tell you something but do you know when the codes were posted? what has been done about curing them one by one fuel rail pressure has it been checked? lack of comms BSI to Aircond? Waste Gate?

They all happened at once.

The most common codes (this has been checked many time) are the fuel codes.

The dealer said that the fuel pressure in the common rail dropped to 80psi, but as he said this is impossible with the car still running. That is why he changed all the pressure sensors, but it still reads 80psi when it goes into permanent idle. But it is fine if you turn the engine off and on again.

We did think of a computer error, so he also reloaded the computer, to no effect.

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cachaciero · Post by **cachaciero** » 17 Apr 2010, 09:49

Hmmm...!

Well I wonder what would happen if the rail pressure was normal or close to normal but the ECU "thought" that it was seeing 80psi, question was it 80 psi or 80 bar? 80 bar would be low but not as low as 80psi.
My next step would be to get a pressure gauge plumbed into the rail as a way of checking the sensor calibration. i.e you can see the real pressure on the gauge and then see what the Lexia and hence the ECU thinks it is.

Another thing to look at on the Lexia would be pressure regulator current would expect that to be around 50% and the status of the fuel pump third piston.

cachaciero

fred1 · Post by **fred1** » 17 Apr 2010, 09:53

Hi,

An off the wall thought.

A post today is reporting an injector with high leakoff causing a massive drop in fuel pressure. Aee JamesQ8 entry in Help Desperataly Needed post.

Is it possible that you have a sticking injector (or 2) such that in idle the leak off stick open in some way ?

A check on the leak rates might be useful?

Just a thought

John

Ralfie · Post by **Ralfie** » 17 Apr 2010, 10:03

cachaciero wrote:Hmmm...!

Well I wonder what would happen if the rail pressure was normal or close to normal but the ECU "thought" that it was seeing 80psi, question was it 80 psi or 80 bar? 80 bar would be low but not as low as 80psi.
My next step would be to get a pressure gauge plumbed into the rail as a way of checking the sensor calibration. i.e you can see the real pressure on the gauge and then see what the Lexia and hence the ECU thinks it is.

Another thing to look at on the Lexia would be pressure regulator current would expect that to be around 50% and the status of the fuel pump third piston.

cachaciero

Thanks. Yes, I meant bar, not psi.

I hope to get the pressure checked later, the dealer did not have another pressure gauge for some reason.

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Ralfie · Post by **Ralfie** » 17 Apr 2010, 10:11

fred1 wrote:Hi,

An off the wall thought.

A post today is reporting an injector with high leakoff causing a massive drop in fuel pressure. Aee JamesQ8 entry in Help Desperataly Needed post.

Is it possible that you have a sticking injector (or 2) such that in idle the leak off stick open in some way ?

A check on the leak rates might be useful?

Just a thought

John

Yes, I did have this.

One injector was leaking massive amounts of fuel, so the dealer thought "Ahaa" and replaced it. No leakage now, but the same problem with getting stuck in idle-mode still occurs. grrr!

Strangely, the car performed quite well on the road with the stuck injector, just a bit smoother when it was replaced.

My thought was to increase the idle rpm to 1000rpm, because if I keep my foot on the pedal with a higher idle, this getting stuck in idle-mode does not occur (makes for tricky driving while decelerating or sitting at traffic lights).

I asked the dealer if he could raise the idle (a 20 second job on an old petrol-carb car), and after much deliberation, the answer was "NO !!".

Apparently, the computer says no!!

.

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cachaciero · Post by **cachaciero** » 17 Apr 2010, 10:16

With respect to Fred1's comments if there was a heavy leakage through the injector leakoff or indeed anywhere else for that matter I would expect the fuel pressure regulator current to be at an extreme i.e max current or min current sorry can't say which as I don't know for sure which way it goes but if it's struggling to maintain pressure it will be on it's limit one way or the other. If that should be the case then I reckon the injector leak of test would be worth doing.

cachaciero

Ralfie · Post by **Ralfie** » 26 Apr 2010, 10:53

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Ok, so I changed the MAF, and all seems fine for the time being. Not had any 'stuck in idle', starting is quicker, and the running at high speed appears smoother (subjective?? confirmation bias??).

As this was an intermittent fault things could change at any time, but it is looking good so far.

Will let you know.

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Ralfie · Post by **Ralfie** » 06 May 2010, 10:20

Ralfie wrote:.

Ok, so I changed the MAF, and all seems fine for the time being.

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Car still running well, with none of this getting stuck in idle. Things are looking good so far..... (but not done any long journeys recently)

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