Citroen C5 X7 throttle hesitation

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rrijken
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Citroen C5 X7 throttle hesitation

Post by rrijken »

After solving the AL4 and electric problems, I can now work on the next problem, sometimes at start the car hesitates and does not react to the throttle pedal. Looking into this now and read about problems with the position sensor, the VOD or the MAF sensor. Will start with the MAF sensor guess.

what happens sometimes is that I start the car, put it in D and press the throttle pedal, parking brake is released but revs drop from around 700 to 500, rarely it stalls, but sometimes does. Releasing the throttle and waiting for a bit before trying again usually solves it. At lights sometimes as well that the car really hesitates. Pressing it in further usually makes the car go then.....

Have now already replaced the sensor under the VDO (MAF? MAP?), but no change really.... Throttle body is completely clean of any crud....

Here as well, help appreciated!

Robert

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

Anybody any ideas?

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GiveMeABreak
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Re: Citroen C5 X7 throttle hesitation

Post by GiveMeABreak »

You really need to get Diagbox on it. If there are problems with the engine ECU, gearbox ECU or other areas you should have some stored fault codes. If you can get those and post them up we can help with those, but otherwise with these it is going to be guesswork. The reason being is that the systems are so integrated, that a problem with the ESP system can affect the electronic handbrake, cruise control, auto gearbox for example. Any problem with the air or fuel system and the engine ECU may put the vehicle into a downgrade backup mode until the fault either disappears on its own (in the case of a temporary fault) or the underlying problem is dealt with.

So it really needs some diagnosis to start with.

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

diagbox on there but no fault codes stored. At dealer they told me it had below historical faults stored:

P0495: cooling fan fault, have a spare but have not exchanged yet as it is a bumper off job and no cooling problems to be seen (fault also does not appear anymore), related?
P0571: stop switch fault, exchanged
P0730: clutch slip, solenoids changed no problem anymore.

Should I look at the sensor readings and see if they are within range? If yes, what sensors and where in diagbox should I look?

Help appreciated!

Robert

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

Have changed the throttle pedal to another used one from an x7 v6, no change so guess it is now on to the vdo....

Have noticed though the following:

1. When stopped at lights and when they turn green, I let go of brake and press accelerator immediately, the car hesitates a lot untill I press the accelerator further. Car will then pick up quickly as I have pressed in the pedal quite a lot.

2. In same situation as above, if I let the car creep forward on the transmission alone for a bit and then press the accelerator it picks up almost instantly without hesitation.

We had this from when we bought the car, so before I changed around the solenoids. Any ideas? Should I change the vdo?

There are no error codes to be read anywhere. If anybody can give me hints on where to look in Lexia to see if numbers are off then that would be really appreciated!

Robert

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GiveMeABreak
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Re: Citroen C5 X7 throttle hesitation

Post by GiveMeABreak »

What are you referring to: VDO / VOD?

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

Marc, thanks. Referring to the throttle body.

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GiveMeABreak
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Re: Citroen C5 X7 throttle hesitation

Post by GiveMeABreak »

So you are using Diagbox, have ran a global test and there are no faults reported?

Check the history of faults in the log, in case there have been any temporary self cancelling faults logged.

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

Trying to read the faults log, but after 2 hours waiting and the PC still processing I gave up.

Does it take this long to load the journal?

Diagbox 7.04 on a windows xp PC with only 750mb memory

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Re: Citroen C5 X7 throttle hesitation

Post by Hell Razor5543 »

rrijken wrote:
16 May 2020, 07:12
Trying to read the faults log, but after 2 hours waiting and the PC still processing I gave up.

Does it take this long to load the journal?

Diagbox 7.04 on a windows xp PC with only 750mb memory
I would try to upgrade the memory to the maximum the PC will support (remember that Windows XP can only address a total of 4GB RAM, including video RAM). 768MB really is not enough for DiagBox to work, let alone work well.

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

Reading of the faults took forever.

Have a lot of A4C5 illumination of third brake lamp short circuit to positive. Brake light works though.... No idea if it works all the time. Brake switch? This error goes back all the way till when I bought the car and the dealership changed over the brake switch for a new one.

All other errors are related to the me having not adjusted the lever when I changed the solenoids.

No errors related to any sensors or the throttle body. Hesitation is sometimes really irritating and in some situations plain dangerous for example turning right with traffic oncoming. If it hesitates it is an accident waiting to happen. Waiting for it to be completely safe it will be irritating for the people behind me.... Reason I would want to fix this.....

moizeau
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Re: Citroen C5 X7 throttle hesitation

Post by moizeau »

Note the faults, then erase them, drive the car a bit, then recheck for faults. Old ones that aren't relevant hang around.

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

Still have the hesitation but found out that when the airco is off, the hesitation is almost gone.... Alternator gives enough current, battery has been replaced with a new one in April. Any thoughts on this?

Ignition system has been renewed when we bought the car (new plugs, new coil) so starting to suspect the fuel delivery, or the o2 sensors. Will drive around with the PC attached to look at fuel pressure, O2 sensor readings and injectors. Any hints, tips on what to look for?

Lexia throws up no errors and other than the hesitation (at times really dangerous as the car is not responding to throttle, drops rpm to 500 and close to staling before it recovers and goes, sometimes more than 5 seconds...) the car is fine..... Really want to fix this.... Also no faults in journal...

As always, help appreciated as I am now completely at a loss

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Re: Citroen C5 X7 throttle hesitation

Post by xf1ref »

The best idea is to log while driving the car, and then to analyze if the values requested are almost the same as the values given. Sudden drop of fuel pressure, misfiring, throttle pedal sensor, etc..could be the cause for hesitation. Maybe in lexia there are available tests to be done with the engine running, you should try also this.

rrijken
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Re: Citroen C5 X7 throttle hesitation

Post by rrijken »

thanks. Will report here again after having taken it for a drive.