THP 150 Stutter under acceleration

[Jonbays]

Well Well! 12,000km old THP150/155? (build date12-11) and I get my first little taste of what seems to be a commonly reported problem.

Nicely warmed up and all running well but when asked for a big roll on acceleration burst from 70-90kmh in fourth I got three quick very noticeable stutters. Sort of like pinking or pre-ignition sound then back to normal. Maybe even over boost or waste gate not opening up fast enough? Couldn't reproduce the event though and tried many times. The ECU was being logged at the time though and nothing unusual showed up the following is the fault log thrown up.

Fault log report generated by Torque for Android
=================================================

Vehicle VIN: Not present
Vehicle Manufacturer: Unknown
Vehicle Calibration ID: Not present

Current Fault Log
------------------
ECU reports no current faults

Pending Fault Log
------------------
P1385: [BMW] Knock Sensor 4 Circuit

P2336: Cylinder #1 Above Knock Threshold

Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
ECU reports no other fault codes logged

End of report.

A dump of the boost pressure logged over the period was 21.75566101, 21.61062241, 22.48085022, 4.35113239, 22.04573631, 24.22130203
This is PSI not calibrated though so not sure about the absolute value only the trend. This is exactly what it looks like when you change gears in hard acceleration but by the time and GPS I can associate this with the event.


It's been running fine ever since but what do you think it is? What should I do? Take it to Citroen service just in case I do need to get a warranty claim in the future?

[lfcrule1972]

There are plenty of owners or ex owners of THP150's who should be able to offer specific advice, if it were me I would take it to Citroen asap to log the fault on their records and see if they suggest anything. Was yours built in December 2011 or November 2012, in the UK I'd say the former from the dates you gave 12-11

[Jonbays]

Build date on the plate is 12-11 December 2011 being built in France and then shipped over to Aus and first registered here in May 2012.

[lfcrule1972]

Cheers, us Brits confuse our dates and our US/Aussie cousins I think The confirmation should help with the advice that will follow later....

[cyclone]

if it were me I would take it to Citroen asap to log the fault on their records

This. That way you can prove a history of problems if it ever goes boom.

[DickiJ]

This issue will not go away on it's own and will only get worse. You'll soon be on first name terms with your local service department I'm afraid.

[Jonbays]

This issue will not go away on it's own and will only get worse. You'll soon be on first name terms with your local service department I'm afraid.

Exactly my fears! Annoying I couldn't reproduce the stutter though. Hard to get help from a mechanic based on a fault code without being able to demonstrate the problem.

Will book the car into the local dealer for a look this week and let you know what the outcome is.

I expect nothing better than being fobbed off and realised when I bought the car that it would need careful mechanical attention. Still good to get the faults logged into the Citroen service dept in case bigger warranty claims come up next.

[Chris_Blue]

Hi Jonbays
Think December 2011 makes it a THP 150, but could be a first 155, but think first were made Jan 2012
Anyway- if the problem persists, you could always do the rear PCV delete, and keep the original pipe, and if the delete doesn't sort it, then put the pipe back on and send it in to dealer.
Or stick a catch can on it.

Have you a photo of the PCV pipe in situ? and what fuel do you use? (Front PCV is easiest to see, RHS of engine)

Safest way is dealer all way thru obvs- but they might not attain a remedy for some time if they have no experience of the problem, as the history in the UK seems to suggest.

[Jonbays]

Hi Jonbays
Think December 2011 makes it a THP 150, but could be a first 155, but think first were made Jan 2012
Anyway- if the problem persists, you could always do the rear PCV delete, and keep the original pipe, and if the delete doesn't sort it, then put the pipe back on and send it in to dealer.
Or stick a catch can on it.

Have you a photo of the PCV pipe in situ? and what fuel do you use? (Front PCV is easiest to see, RHS of engine)

Safest way is dealer all way thru obvs- but they might not attain a remedy for some time if they have no experience of the problem, as the history in the UK seems to suggest.

OK it's in the local Citroen dealer service department now. They had a look at the logged error codes I saved and checked the ecu to see if I had cleared them and they were still showing as pending as I hadn't. So far the only word I have is they need to keep the car for a few more days and email France about the issue. looks like it will be a warranty so they are making sure they will get paid first before they go much further.

I see the issue as a poorly developed GDI engine system essentially where they haven't truly understood all the implications of not having fuel injected into the inlet manifold behind the valves and the effect of emission controls forcing them to vent crankcase fumes into the inlet manifold either directly or through a turbocharger and intercooler. The catch can would appear to be a good idea but I will wait and see what Citroen do. My guess is they will clean up carbon deposits with a "cleaner" and send me on my way. I will ask them how this fixes the problem and is this going to be done every 10,000km as part of the normal service now or what? How about a THP155 PCV system upgrade? Going to be very interesting to see what happens not expecting miracles just want to keep it going and get it back sooner than later.

BTW they did also find the clutch squark problem too and want to take off the gearbox to have a look at that while they have the car. That should be simpler to fix but I wonder whether it is the Dual mass flywheel mech rather than the clutch pressure plate or release bearing or fork but this I do trust them to fix.

[Jonbays]

oh only ever used premium unleaded Shell V-Power which is a 98 octane premium fuel. http://www.shell.com.au/products-ser...wer/about.html

[Chris_Blue]

Jonbays- agree with all you say in post #9. They will clean the carbonised valves with a "very expensive cleaner"
They've been doing that since early 2010 when the problems on the 150 first started in UK
Catch can or WMI is best methods to avoid the problem so ive been told, and catch can isn't foolproof, as Czar has outlined. Most are only 35% effective, think he said. But it still works well by removing suspended oil and gunk and returning it to the engine

Reason I asked for a photo of your engine, is that the PCV pipework on the THP 155 has changed from the 150, and it may be this that has seen a drastic drop in issues with the 155 engine, so far.

[Jonbays]

Jonbays- agree with all you say in post #9. They will clean the carbonised valves with a "very expensive cleaner"
They've been doing that since early 2010 when the problems on the 150 first started in UK
Catch can or WMI is best methods to avoid the problem so ive been told, and catch can isn't foolproof, as Czar has outlined. Most are only 35% effective, think he said. But it still works well by removing suspended oil and gunk and returning it to the engine

Reason I asked for a photo of your engine, is that the PCV pipework on the THP 155 has changed from the 150, and it may be this that has seen a drastic drop in issues with the 155 engine, so far.

Should have taken the photo of the engine bay before I put it into the garage but didn't unfortunately. Not at all sure which model THP I have being almost on the cusp of the THP155 but suspect it will be a THP150. When I get it back I will take that photo.

[Chris_Blue]

Would be interesting to see a piccie of a new PCV front pipe, and see how much it costs. Then ask the Mechs at Citroen
if its worth upgrading the PCV pipes as a fix?

[Jonbays]

Well just had the call from the dealer service dept. The engines coming out so they can remove the cylinder head, inlet manifold and clean it and inspect the pistons and bore and they will replace the turbo which they say has been blowing oil into the engine!

Maybe get the car back in two weeks.

Not the first time it's happened at the dealer they seem to be familiar with the drill but first time they traced it to the turbo which is curious.

[Chris_Blue]

Havent heard that explanation before