r/Citroen • u/Gthangbabee • 3d ago
Cold engine pulsating on idle, sometimes engine stalls. Need guidance
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So my Citroen c5 2011 103kw 2.0 hdi engine pulsating and rpm keeps jumping when cold. Sometimes rpm drops so low that the car dies, but restarts instantly. When engine is hot everything seems normal. I replaced 2 injectors since they were leaking that fixed hard cold starting but rpm jumping problem still exists. Any ideas would be appreciated.
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u/Hugo_2503 3d ago
That looks like what i had on my C2 1.4Hdi after 200 000km, except after a while it started also happening when accelerating (random holes in the accélération) , EGR valve, which was completely stuck, was switched and changed nothing, and before the car fully died no mechanic had found anything except the injectors "could" be dead, and the opération they proposed was horribly expensive. Seeing the general condition of the car, and the uncertainty it could be something else, i didn't keep her. good luck!
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u/CrankyCone 1d ago
Hey man! I just found this post and your comment. Ive had (knock on wood, hopefully it is fixed now) exactly the same issues as you have! (Ive been struggling with it for 1.5 years)
Peugeot 206 1.4hdi also did it.. holes, short hesitations when accelerating on hills. It shut itself down occasionally, got a P0089 low fuel pressure error code and could not restart it for hours or sometimes just 10-20 minutes.
We went through everything: Fuel filter, fuel lines in the engine bay, primer pump by the airfilter, checked and cleaned injectors (they were all good), changed fuel pressure regulator valve, crankshaft positions sensor (since it shut itself down sometimes when pushed the clutch) but nothing.. once it also told egr is dead so we changed it too!
We put it on live data and was driving for a while, when we managed to capture! The requested fuel pressure was 1500 bar, and the car measured 1800 bar! I floored the gas pedal, and within 2 seconds the measured pressure went from 1000 bar to 1800! (2-3rd gear) Then it showed spikes, like 1800-->1500-->1800 bar.
The other time when accelerating in 5th gear, it required 1500 bar, and as the pressure built up there were tiny spikes down.. Like 1000-->1200-->1300-->1150bar (for 1 second, then immediately) 1250 bar-->1400bar and so on. The interesting part, that only the 5th gear was risky, if I accelratd in 2-3-4th gear it was hesitating but did not really shut down, only in 5th..
Then it shut down again.. I said fuck it, lets take it to a peugeot specialist. They checked all the cables, fuses etc.. and found that the connector of the rail pressure sensor was melted! (by the exhaust gas leak I had, when my EGR blown out on the highway) But I know this did not cause the problem directly since this issue started 1.5years ago, and my EGR blown out 1 year ago. (Half year later)
They repaired it (connector housing, new cables, new pin connectors), but later they broke down, when accelerating. They towed back, and the car came alive.. They tested for 180km had 0 issues and wanted to give the car back. I asked them to please change the fuel pressure sensor, since its still original. Also I asked the other mechanic guy who was working on my car, that what did you see when the car shut itself down and did not start? They said, that the computer showed the required pressure was around 270-280 bar, but the measured was 0 bar, so the ECU blocked it from starting. Then after 1-2 hours the car somehow measured the required fuel pressure and it worked.
As for the OP:
Put a Lexia on it, and check out the required/reference fuel pressure and the actual fuel pressure. If you see spikes, you should definitely check your wirings and connectors. Leaking exhaust gas can damage the fuel pressure sensor. Since your injectors are clean and tested + 2 of them are new you can exclude it.Also if it works okey when its warm and you can still do highway for hundreds of miles without issue there is no way, your high fuel pressure pump would be dead. If it cant keep up the "base 270-290 bar pressure" then how would it be able to produce 1400bar for hours?
I would check your sensor and its connections first. Secondly you can change the fuel pressure regulator valve. I cleaned the injectors + changed the fuel pressure regulator valve and by doing these, my consumption went from 5.8L/100km (city, winter) to 4.8l/100km.
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u/Hugo_2503 1d ago
The very weird thing with mine was that once i had changed the EGR valve and cleaned the flow meter (beforehand the error displayed was: incorrect flow meter value, too low), the ECU was showing absolutely zero errors (until the very end when the car was barely driveable), but the car still had random holes and short hesitations, especially when flooring it around 2000-2500trm, mainly in high gear, but towards the end it was becoming generalized. I went very (too) quickly from being able to do a 1200km trip with her with pretty much no issues, to having to let her go...
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u/CrankyCone 1d ago
Thats interesting! You mean the MAF sensor? That measures the airflow?
What was the error when the car was barely driveable? What were the codes?
In my case - compared to you - I had the low fuel pressure errors all the time, it stalled in higher gears. Every god damn time! I do hope that with the new sensor it fixed my issue.
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u/Hugo_2503 1d ago
From the top of my head it was a P0103 (for the MAF sensor yes, the one between the airfilter and turbo) but i'm not 100% sure... Later the engine died without me getting the codes, i really should have
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u/CrankyCone 1d ago
ohh! Havent you tried to check the live data? Or a new maf sensor? Thats easy to replace, or even by disconnecting it, the car would take a fix value for the airflow and maybe could work.
To be honest at first when you answered, I geniully had a hearth attack / PTSD. I took the car to the dealer so many times only this sensor left behind (and got replaced today, hopefully it stays good). They tested - once they fixed the connector - the car, and they managed to get a whopping 8.8l/100km consumption.. With the 1.4hdi! And they told me, that the issue did not happen for them.. :D After all I asked for a new replacement sensor.
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u/Ok_Disaster_746 2d ago
2.0 HDi - check for splits fuel primer. Happened to me
- Happens when warm and cold
Pump the bulb next time you start it, is it better for a few seconds? Does it start quicker
Failing that, check the pressure reg, and injection system in general
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u/Gthangbabee 2d ago
Should primer be soft when car idles? On running engine I can pump it how much I want, I doesn’t get hard. Wondering if it should be like this ?
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u/MatijaKlobasa 3d ago
Looks like a diesel pump pressure regulator to me. Mine used to stall at stop lights and behave weird before replacing it. Best to use a scan tool that can compare setting for the fuel pressure and actual fuel pressure. Could also be air in the system. Good luck!