Xsara Picasso - hesitation - maybe the fuel tank pressure regulator

[captainkephart]

Hi All,

On a 57 plate 1.6DOHC petrol Xsara Picasso I'm struggling to work out whether the fuel pressure regulator is part of the fuel pump mechanism or a separate gadget in / on the fuel tank ...

If it's separate, I've no idea what it looks like to order a new one ...

Reason? The good old Citroen Engine Fault Light merry-go-round (not!). After a couple of years of the light coming on, being 'fixed' and then 500 miles later coming on again - I now have a 'proper fault' showing up in severe hesitation about 10 mins after driving off. It's possible (just) to go along in 4th at about 30mph but you can't accelerate.

Seemed to me like fuel starvation (hence the fuel tank question) or an ignition coil fault?
Any suggestions much appreciated.

Ciao, Captain K

PS: I won't give chapter and verse on what's happened so far (unless you are interested!

[Hell Razor5543]

Hello, and to the Forum. Something that would help is if you post the VIN here. That will allow a Moderator to look up your vehicle and find out exactly what she had when she rolled out of the factory. For security reasons the VIN will be obscured so only Forum staff can read it.

Something else that could help is if you get her connected to a DiagBox system, to read any fault codes (and to reset them). Generic readers probably cannot help you here. However, there are Forum members with such equipment who are also willing to help other Forum members. The following link could be of help;

[captainkephart]

Hi, Thanks for the welcome!

VIN is: VF7**************[VIN obfuscated, can be read by forum staff]

Yes, the codes ... so many, so beautiful ... !

I have an OBDII reader (from TOAD with an ELM327 USB connector) with a setting for Peugot/Citroen data.
The most recent codes - which came about 100 miles **before** the hesitation(!) are below.
Since the serious hesitation there have been no additonal codes:
Stored Diagnostic Trouble Codes (DTC) (Mode 03)
P0130 - O2 Sensor Circuit
Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
Controlled by: ISO/SAE Controlled Code (Core DTC)
Controll Unit: $10 - Engine
Pending Diagnostic Trouble Codes (DTC) (Mode 07)
P0130 - O2 Sensor Circuit
Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
Controlled by: ISO/SAE Controlled Code (Core DTC)
Controll Unit: $10 - Engine
P0135 - O2 Sensor Heater Circuit
Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
Controlled by: ISO/SAE Controlled Code (Core DTC)
Controll Unit: $10 - Engine
Permanent Diagnostic Trouble Codes (DTC) (Mode 0A)
No Trouble Codes

Do you think it helps to give the whole Error code history / parts replaced over the last year???

Best wishes, Captain K

[captainkephart]

Hi All,
OK. 'GiveMeaBreak' Marc has suggested I give a bit more detail.
It's the usual sort of Engline Fault Light ECU Elusive Butterfly hunt that many people have had ... but ...

Mine went like this. S/H Xsara Picasso 1.6 DOHC Desire (petrol) bought 2018 with just under 30k (genuine) miles on the clock. Previous driver old, had kerbed the N/S and damaged bodywork badly several times till banned (this may be relevant as ECU is on N/S ... item 9 below).

1. Car great for first 2k miles. Then, for no apparent reason, Fault Light on (FLON). OBD says downstream oxygen sensor. Maybe there's an intake manifold air leak? Bingo, one of the nuts is missing. Replaced nut and sensor. Fault not cleared down. Light went off (FLOFF) after a few miles anyway. Hurrah!

2. Off to Ireland (with boat). About 500 miles later, FLON. Fek! Drove back to UK. OBD says same. Hmmm. Local garage (Lionel, excellent guy, ex-F1 mech) says 'Ha, you need to replace lambda / oxy sensors in pairs'. I do that (don't clear fault). FLOFF after about 50 miles. Hurrah!

3. Now it gets weird. After a few hundred miles FLON. Sigh. OBD says:
Stored Diagnostic Trouble Codes (DTC) (Mode 03)
P0137 - O2 Sensor Circuit Low Voltage. Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
Controlled by: ISO/SAE Controlled Code (Core DTC). Controll Unit: $10 - Engine
Pending Diagnostic Trouble Codes (DTC) (Mode 07) says the same.
I check the wiring and unplug / plug all connectors, can't see any errors.
Happen to have run the tank down so 'Low Fuel' light had come on.
When I filled the tank, guess what? FLOFF ... WTF!

4. Off the France. On way to ferry, FLON. Thinks - this car is attention seeking ...
BUT, more weird. About to leave ferry, change instrument display to KM/H and to French (yes, bonjour car). Guess what ... yes FLOFF!!!

5. I now decide there is no fault. I look at various car posts. This FLON / FLOFF stuff seems to be general Peugot / Citroen error. People say they have replaced ECU and all sensors and still happens on some cars!

6. OK, continue holiday. Ah, FLON. And now something different. The ECU has shifted into 'safety' mode. Rough tickover, high fuel consumption etc. At gite disconnect battery and remove plugs from top of ECU. Aha! Oil (brake fluid?) in middle plug socket. Clean out and check everything else. Re-assemble, battery back on. Ignition on, leave with doors open till the car enters 'Economy Mode'. FLOFF for about 50 miles. FLON. 'Merde!' (you see, we do speak French). Have to return to ferry anyway. Another 200 miles FLOFF all on its own! Hurrah!

7. Get back, put OBD on. Get this (none Pending):
Stored Diagnostic Trouble Codes (DTC) (Mode 03)
P0130 - O2 Sensor Circuit. Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
P2191 - System Too Lean at Higher Load. Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering and Auxiliary Emission Controls
P2177 - System Too Lean Off Idle
Vehicle Area: Powertrain (P). Area of Vehicle System: Fuel and Air Metering and Auxiliary Emission Controls
Controlled by: ISO/SAE Controlled Code (Core DTC). Controll Unit: $10 - Engine
Maybe there's an air leak somewhere? Decide to do a service, replace fuel filter and oil / air filter, new plugs, And replace fuel tank breather valve (the one by the O/S headlamp). At this point, I didn't know how to use the TOAD OBD to clear the faults. So started driving again ... 50 miles later FLOFF. Maybe hurrah?

8. In weirdville again. 500 miles later FLON (after having to sit in stopped motorway traffic on hot day - not overheating, but ...?). None of the previous 'tricks' worked (low fuel, changing to KMH).
BUT, by chance a few days later, started the car with both doors open. FLOFF! Car goes along very happily. Fuel consumption low, tickover just fine. Great! Then, oh dear, days later FLON ...

9. BIG AHA MOMENT. All those nearside car accidents. What might have been damaged / not repaired properly. BINGO. Front N/S passenger door plug NOT fully inserted. Maybe the external temp sensor sending rubbish. Clean all that area and correctly insert plug. Plus, when I bought the car, I had a tow bar fitted - took out the linings in the rear compartment - a nightmare rats nest of wires, including exposed ends. Tidied all up and insulated. GLOOM ... makes no difference.

10. Have to go to Germany. Start, then goes into FLOFF, but about 200 miles along autoroute FLON. Car in safety mode again. I'm beginning to wonder if the fault is with the throttle body (Why? you ask .. because I'm getting paranoid about this car). Buy new throttle body (ouch, expensive!). Fit it, guess what, FLOFF ... for 50 miles, then FLON, again for no apparent reason. Depression. Where's the nearest crusher???

11. I have a hard think. Now, maybe it's none of these things? But what do I do every time I replace a part. OF COURSE, I disconnect the battery! I check the main connector under the bonnet, slight corrosion. And the battery terminals, crystals around pillars. Clean throughrouhly and vaseline. FLOFF. Lots of fingers crossed. BUT, on way back to UK, FLON. Just ignore it. Drive more than 1000 miles with the light on - mostly autoroute where no problems at 130KPH. When I get back, OBD says:
Stored Diagnostic Trouble Codes (DTC) (Mode 03)
P0134 - O2 Sensor Circuit No Activity Detected. Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
P2191 - System Too Lean at Higher Load. Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering and Auxiliary Emission Controls
P2177 - System Too Lean Off Idle, Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering and Auxiliary Emission Controls
I clear those. FLON almost immediately. OBD says something different:
Stored Diagnostic Trouble Codes (DTC) (Mode 03)
P0130 - O2 Sensor Circuit, Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
Pending Diagnostic Trouble Codes (DTC) (Mode 07)
P0130 - O2 Sensor Circuit, Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
P0135 - O2 Sensor Heater Circuit, Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
Clear those, FLOFF.

12. LAST NOTE! (Thanks for reading this far). About another 500 miles later a REAL problem appears. The car has never accelerated evenly. It would accelerate fine and then feel like a turbo was kicking in (there isn't one) and you'd have to ease back slightly. Now though, accelleration hesitates like there's fuel starvation / ignition fault. You can get it (slowly) up to 60mph, then it seems happy, just won't accelarate properly.
BUT, NO ECU fault light! OBD says no faults, none pending ... WTF! (times several).

I'm thinking of fitting new ignition coil, coolant temperature sensor and crankshaft sensor. And maybe even replace the fuel pump in the petrol tank. That's back to my first question ...

I'm struggling to work out whether the fuel pressure regulator is part of the fuel pump mechanism or a separate gadget in / on the fuel tank ... If it's separate, I've no idea what it looks like to order a new one ...

Does ANY of this make sense as to what's wrong - or have I just screwed it all up by being inept?
Suggestions welcome.

Mind the fog, take care,
Capt K

[Activa TCT]

Sounds to me like lean burn issue. Grab a can of wd-40 and spray around gaskets, see if revs get higher. You have either a big air leak (which isn't noticeable when you drive WOT) or a dying pump.
Given my experiences with xara's, I'd say, change the pump. They die a lot.

Also don't overfill tank and check if tank cap fits properly. If you overfil till fuel pours out, all kind of nasty things go on with evap canister. Which - may also be broken.
Do brakes get hard-er when it is causing troubles ?

[GiveMeABreak]

I think to be honest the appearing and disappearing of the Engine Management Light (EML) is working correctly and has nothing whatsoever to do with opening closing of doors, changing the MPH to KMH etc.

What is happening is normal in that every time the driving conditions cause a particular fault, the engine ECU is engaging a back up mode which will result in some degradation, including reduced engine power. These may be temporary faults, in that as soon as the conditions that caused the fault clear (which can be as simple as stopping the engine and then restarting it), then the vehicle performs as normal - Until the same process repeats itself again.

So there is an underlying fault (s) that need to be addressed - and unfortunately given the age of the vehicle there is limited in depth information apart from the standard OBD codes listed.

[captainkephart]

Hi Marc,
Useful summary, thanks ... I just wish I knew what the 'underlying fault(s)' are!
I'm still replacing parts to see if I can find it / them ... seems a futile and expensive task.

What's the posibility that the ECU and/or BSI are from another car (becuase this one has had its N/S damaged) and they haven't been properly re-initialised?

Today, have replaced coil pack, crankshaft and temperature sensor.
Checked spark plugs. Lean lean white ceramic tip. Suggestive of fuel pump fault after all?

Noticed that the fuel rail is not rigid. The two bolts are done up, but you can push it slightly back and forth as if it is in rubber supports. Is that right? On my older (2000 LX) Xsara the fuel rain is solid and doesn't move.

Anyway, started up the car an drove for 15 mins+. Hesitation still there, though not as bad. Tickover occasionally rough as a tractor.
OBD live data shows it's stuck in 'open loop'. Reports these temporary faults:
Stored Diagnostic Trouble Codes (DTC) (Mode 03)
No Trouble Codes
Pending Diagnostic Trouble Codes (DTC) (Mode 07)
P0134 - O2 Sensor Circuit No Activity Detected. Vehicle Area: Powertrain (P)
Area of Vehicle System: Fuel and Air Metering
P0135 - O2 Sensor Heater Circuit. Vehicle Area: Powertrain (P)

Can it really be that the Oxygen sensors need replacing again?!
I have a new fuel pump but getting the tank out looks a real grind ... will have to wait till early Jan ...

Other than that, I have to admit that I am now completely stumped.
Vehicle is unsaleable, yet still has some value ... sigh.

Thanks again, Capt K

[captainkephart]

Hi all,
Update on this one. I now have had 4 sets of O2 sensor pairs put in since I bought the car two years ago.
At least two of those sets claimed to be NGK but turn out to be cheap and cheerful look-alikes. After they failed, when taken out, they rattled like a broken bulb filament (remember those?

My local garage cannot work out what is 'killing' the other O2 sensors / or causing the ECU to trigger the fault light (error simply says O2 circuit fault, nothing about which bank or anything else).
Could it be head gasket slow leak? None of the usual signs of a gasket leak (no white in oil, or oil in the coolant header tank).

Any suggestions most welcome.

[Hell Razor5543]

Where did you get those O2 sensors from? Some suppliers are less honest than ideal!

[wheeler]

Local garage says 'Ha, you need to replace lambda / oxy sensors in pairs'. I do that (don't clear fault). FLOFF after about 50 miles. Hurrah!

That's a new one to me, Why would you need to do that? the downstream O2 sensor after the cat is there solely to check the cat is working as it should, it has no input to the running of the engine.

Has the garage had a look at the live data from the O2 sensors? What were the readings?
Were the sensors from Euro Car Parts by any chance?

[captainkephart]

Hi Wheeler, yes the failed ones were from autodoc.co.uk
(I think that has loads of look-alikes that lead back to the same source?).

Yes, the garage did look at the live OBD data - said P0130 - O2 Sensor Circuit fault. They were puzzled by the live data, didn't make sense to them ... I have the Toad software myself and recorded a 15-min journey, not sure a screen shot helps. Might take too of your much time.

Ciao, Captain K

[ksanturion10]

Ciao cappy,
have you tried another source for O2 sensors?
I have an universal type, Bosch, from autodoc.bg, and it is working ok, despite I got the sensing "mundstuck" wrong!

BR
Martin

[Matesko21]

Hi, did you solve it? I think I have the same problem.. Oxygen sensor changed 4 times in 1 year.