Picasso 1.6 16V: oil in throttle body plug

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mnde
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Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 22 Jul 2019, 23:52

Hello,

I'm new here, although I've owned Citroens for many years (but not with so much electronics as this one...)
I'm hoping someone may be able to help with a tricky problem my Picasso has been having. It's a 2007 1.6 16V TU5JP4. Has anyone come across (with Picasso or other Cits/Peugeots with this engine) a problem with oil entering the throttle body plug? I unplugged the connector earlier while troubleshooting troublesome fuel system faults and found a significant amount of oil. It has presumably made its way there from the crankcase breather hose attached to the airbox next to the throttle body, and has been messing with the operation of the motorised throttle/ position sensing/idle control and possibly the iat sensor. This I believe has been the cause of engine choking issues (super high fuel trim), hesitation, intermittent driveability issues etc.

I've cleaned up the oil using switch cleaner and cotton buds, and after reassembling and taking the car out on a few short runs, I could feel that things were very slowly getting better. I can read some live data and could tell from that also (lambda 1 and short term trim starting to cycle again, Long Term trim coming down from +24% to +13%). Hopefully some more longer drives will start to see further improvements.

Next step is how to stop oil getting to where it's not supposed to and trace if its related to issues elsewhere... My garage noticed a little oil in the lambda sensor connections and in the ECU main block... Any thoughts welcome!

Thanks,

Mark
new 2.PNG
new 1.PNG
Last edited by GiveMeABreak on 24 Jul 2019, 19:29, edited 1 time in total.
Reason: Pictures moved to first post

mnde
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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 25 Jul 2019, 10:56

Hi all,

Obviously no-one has come across this before... After looking at various pictures/videos showing throttle bodies being cleaned/changed, I'm going to work on the assumption that the only way oil vapour could get to the interior of the throttle body and into the electrical connection is via the throttle shaft seals. I've found a cheap 2nd hand throttle body online that matches the part number I have - but I've also found a new aftermarket Chinese one with "2 year warranty" for £40 - way less than the £180 plus prices I've seen elsewhere. What do you think? 2nd hand and clean it up, or new but unbranded? Either way I'd have a spare to play around with and I could take the original off and clean and inspect fully, and fit a new O ring seal where it fits onto the side of the inlet manifold.

In the meantime its a matter of checking whether there's too much vapour coming through the breather hose, or whether it's a normal amount but going through the throttle shaft seal and condensing at the lowest point where the electrics are......

Any input would be very welcome. It's provisionally booked in at a Citroen/Peugeot independent specialist on Monday.

Kind regards,

Mark

zs&tas
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Re: Picasso 1.6 16V: oil in throttle body plug

Post by zs&tas » 25 Jul 2019, 11:52

Hey man that sucks a bit , a trick I've used is cut an old bike inner tube , couple of inches long , you can unplug the connector and slide the inner tube over it , reconnect and hold in place with zip ties. Its a great barrier against outside water/grime.

mnde
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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 25 Jul 2019, 18:59

zs&tas wrote:
25 Jul 2019, 11:52
Hey man that sucks a bit , a trick I've used is cut an old bike inner tube , couple of inches long , you can unplug the connector and slide the inner tube over it , reconnect and hold in place with zip ties. Its a great barrier against outside water/grime.


Hi there - a great tip :) although in my case the oil is entering the plug from the interior of the throttle body housing via the contact pins.

Mark

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 29 Jul 2019, 15:36

UPDATE:

It's in at a Citroen specialist today. They've found the breathing system is clear, and at the moment they're suspecting the oil pressure switch or oil level sensor as culprit, meaning they think oil is coming in to the throttle body connection via the harness wiring and not from inside the throttle body. They found another light mist of oil in the middle ECU block where I'd got it all clean and dry a month ago.

They're going to check the oil pressure switch plug for oil leakage in a bit when the engine's cooled down. If it is this, pumping oil into the harness and round to other sensors and the ECU they say they've never ever seen it happen on a Xsara Picasso before..... It does make more sense if the oil is travelling along the wiring under pressure, rather than oozing out of the throttle body connection as I thought.

So the ECU may or may not be damaged; all i can do is keep checking all connectors around the harness are clean once they've stemmed the source of the oil, and monitor how the car performs....

Mark

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 31 Jul 2019, 17:26

OK, if anyone's interested it was indeed the oil pressure switch that was leaking... and because of the protective cover over it, the oil was coming through the switch body, filling the electrical connector and wicking down the wiring reaching:

Throttle control connector on throttle body: so motorised throttle, position sensing, idle control valve, IAT sensor
MAP sensor
Both lambda sensors
ECU centre plug

It's running better now - just need to keep checking connectors for oil every so often and cleaning out any I find.

I'm hoping this info might save Picasso/C4/Berlingo/Peugeot 307 etc. owners with the TU5JP4 engine a lot of money - the (long established) garage said they'd NOT seen this fault before in a Picasso. It's worth checking your oil pressure switch occasionally as you may not see any external evidence of leakage until you start getting random hesitation, EML, fault codes to do with O2 sensors/mixture control etc. Apparently it's a known issue with some small-engined petrol Corsa and Astra models around 2008, but I didn't find anything online about PSA cars - except that Peugeot 207s where washer fluid will leak into the loom and the ECU....

Kind regards,

Mark
Last edited by mnde on 12 Aug 2019, 15:18, edited 1 time in total.

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by white exec » 31 Jul 2019, 18:45

Must thank you, Mark, for reporting that issue, and detailing the extent of the problem and finally tracking down the cause. An unusual failure, but given the tubular nature of parts of that loom - something not present on many earlier cars - it follows a grim logic.

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 01 Aug 2019, 00:14

white exec wrote:
31 Jul 2019, 18:45
Must thank you, Mark, for reporting that issue, and detailing the extent of the problem and finally tracking down the cause. An unusual failure, but given the tubular nature of parts of that loom - something not present on many earlier cars - it follows a grim logic.


Thank you. I've been finding advice hard to come by as the majority of Xsara Picasso people online (Facebook owners groups) seem to own diesels, plus this was highly unusual. It's been a very frustrating few months, trying to get a handle on patterns of symptoms; reading codes and understanding what they mean (or reading between the lines); more recently reading live data and trying to interpret what it was telling me, with the help of Google... and all the while, all this was being caused by a £12 switch.

My regular garage had terrible trouble diagnosing what was wrong, but seemed over reliant on EMLs and waiting for the problem to get worse before booking it in. The trouble was there was no pattern, really. Except it always happened when hot: excessive rich running, because the data was saying "lean". Eventually they determined the MAP was giving faulty data and replaced it, together with both lambda sensors which also had recurring faults. The car was better but the problem never really went away over the next few weeks. With the ECU adjusting the mixture and timing one way then the other I was worrying about cat converter damage. I took it back; they noticed oil in the ECU and lambda sensor connections. It got to the point where the car broke down before any EML was triggered - with the computer thinking the engine was running super lean and turning fuel trim up to the maximum - so I was concerned I'd not make it back to the garage! I was convinced oil in the electrics wasn't the issue. Surely the cat was plugged or had failed. I bought a new one to fit, but then found the oil in the throttle body plug..... and things started to make more sense. The ECU couldn't tell the throttle position properly, the idle was rough etc.

Well anyway, fingers crossed, touch wood, things are getting better!

Mark

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 11 Aug 2019, 21:52

Well, touch wood, fingers crossed, I feel like I've got my car back!

I cleaned some more residual oil from the ECU centre plug and socket using contact cleaner, and for good measure I did the same to the other 2 ECU plugs and sockets even though they looked clean. I wanted to remove the throttle body but couldn't figure out how to free the clip that holds the wiring!! So I cleaned out the plug and socket again, then cleaned thoroughly inside the body, the throttle butterfly, where the butterfly closes against the body, using intake cleaner and clean cloths - I removed a fair bit of dirt. I finished off by cleaning inside the air filter lid.

I took the car for an Italian tune up, and a bit more normal driving, and it feels like it's got all its power back, no hesitation etc. When I got back home, I found *no* fault codes stored 😁

Cheers,

Mark

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by picassodad » 12 Aug 2019, 10:24

Wow, thanks for the heads up on that one, maybe thats whats wrong with the lads 1.8dohc bag of xxxxx, i mean wonderfull picassso, will have a looksee.

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 12 Aug 2019, 15:45

picassodad wrote:
12 Aug 2019, 10:24
Wow, thanks for the heads up on that one, maybe thats whats wrong with the lads 1.8dohc bag of xxxxx, i mean wonderfull picassso, will have a looksee.
Thankyou! It's unfortunate that it's cost me over £500 in garage fees and much internet research to get where I am today, but you live and learn. It was impossible to know that the oil pressure switch was the culprit as there was no external evidence because of the protective cover over it. All the leaking oil was going straight into the wiring harness and migrating all over the place. Even after my garage discovered oil in the ecu and lambda sensor wiring there was nothing online that suggested it was a known issue for PSA cars, hence they were concentrated on MAP and lambda sensor faults; it was only common sense that eventually pointed the finger, after I stumbled across the oil in the throttle plug, then the Citroen specialist I took it to ruled out the other potential causes and found the smoking gun. Along the way I've got to know how the engine ECU acts on feedback from various sensors, and I can now read and understand many fault codes, can reset them, and interpret live data now I have a couple of handy OBD scan tools: a Launch Creader and a bluetooth scanner that works with the Torque Android app. In a way I've saved a lot of money being able to do this myself, so my investment and research paid off.

It was fantastic driving it last night and this morning, seemingly back to it's old self :D I got quite close to the point of throwing in the towel... I hope you get your lad's Picasso sorted :)

Cheers,

Mark.

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 13 Aug 2019, 22:39

Seemingly I'm not quite out of the woods. After driving earlier including up a steep hill slowly in low gear, the EML came on and I knew what the fault code would be. Sure enough when I got home my scanner read P0141 - rear lambda sensor heater circuit. So I'm going to check for oil one more time in its connector plug, and the ECU centre plug/socket, and if I find none the next step will be to order and fit a new rear lambda. I've read in the case of Corsas and Astras that have this problem of leaking oil pressure switches forcing oil into the loom, oil typically contaminates the rear O2 sensor as it is the lowest point in the harness, and permanently stops the heater circuit functioning properly. And that it should only be replaced if all residual oil in the loom has stopped reaching the sensor plug. If anyone's interested, here are a selection of the many forum threads I've been reading about problem Vauxhalls!

https://www.vectra-c.com/forum/showthre ... maging-ECU
https://www.migweb.co.uk/forums/other-m ... lease.html
https://www.thecorsa.co.uk/forum/techni ... y-clicking

Kind regards,

Mark

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by Hell Razor5543 » 14 Aug 2019, 06:24

I was thinking as to how to prevent this re-occurring. What I was thinking was (based on the fact that oil seems to be passing along the wiring harness) was to thoroughly clean the wiring, and (then using a candle) then fill in the space using hot wax, followed by wrapping the wiring bundle (using amalgamating tape or, if possible, heat shrink).

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by white exec » 14 Aug 2019, 07:01

Not sure about the exact layout of the "pipework" loom, but if the oil is being injected at the oil pressure switch, would it be possible to simply strip back the original sleeving/covering by a cm or so, so the oil just visibly drips out, rather than being fed along the loom?
On many cars, wiring sleeving 'stops short' when it arrives at a connector, leaving a cm or so of the connecting wires visible.

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Re: Picasso 1.6 16V: oil in throttle body plug

Post by mnde » 27 Aug 2019, 14:23

I'm still suffering on and off with this. At the weekend we took the Picasso for its first long drive in a long time, around a 100 mile round trip to the New Forest and back via the M3 etc., with speeds up to 70, but also including some hold ups in heavy traffic, and it performed faultlessly. On our return my reader found no codes stored, and all monitors had completed successfully.

The next day I took it on a shorter journey in stop start traffic, but still involving a stint on a dual carriageway and it started to feel hesitant on the over-run and light throttle. As we were parking up the EML came on (P0141 rear lambda heater circuit), which I reset. Yesterday again I noticed a certain lack of power sometimes and hesitancy on the over-run, but no code was stored (ambient over 30 celsius). This morning (17 celsius) it was better again!

I'm wondering if the hotter it is outside, the more likely it is, in combination with the heat generated by the engine, for residual oil in the circuit to be causing trouble?

I did find and remove some oil a few days after my previous post: a little inside the ECU centre plug/socket, a little in the lower O2 connection, a little in the throttle body plug. But I've not checked now for over a week.

My next plan is to try swapping the lower and upper lambda sensor around to see if the P0141 fault code turns into the equivalent bank 1 sensor 1 heater circuit code, which would (hopefully) identify the sensor rather than the ECU being at fault. What I'm guessing is happening is that the fuel system is going intermittently open loop (EDIT: as in rear O2 sensor not being monitored for its voltage feedback) especially at idle or the overrun because the sensor is dipping under its min operating temp and the ECU is trying to turn on the heater circuit but it's not responding, or its slow, the O2 sensor isn't reacting (showing a change of voltage) within a set time frame and the ECU is responding by switching to the default-rich mode, hence the hesitation and the feeling of having lost a few horses.

I know that 2 stored P0141 faults within a certain timeframe will light the EML. What I don't know is how quickly a single pending code (eg P0141) will be cleared if the next set of O2 bank 1 sensor 2 tests all pass during the drive cycle, and thus how quickly the fuel system in "fault" or otherwise "default rich" mode will resolve to "normal".

I now have a bluetooth OBD reader that works with the Torque app, so I'll have to learn how to record certain PIDs over a journey. e.g. O2 bank 1, sensor 2 voltage and FUELSYS status (OL, OL-Drive, CL, CL-Fault etc.)