508 2013 1.6THP Cold start issue

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Clutchman11
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508 2013 1.6THP Cold start issue

Unread post by Clutchman11 »

Hi all,

I'm having an issue which I haven't yet been able to find an answer to in the forum despite searching and reading for some time now.

My apologies in advance for the long winded description:

When I start my car with a cold engine, it has no power. As in, it won't move from standstill without applying throttle and slipping the clutch. This issue remains as long as you baby the throttle.
After flooring the accelerator once or twice (RPM's never come above 2-2.5k), I get a CEL and a "Engine Fault" warning. This is sometimes accompanied by a P1340 fault, although not always.

Once I get the above fault, I need to turn the engine off. Wait 10-15 seconds, turn the engine on. Shut off again after a few seconds. Turn on the ignition (no start), if there is a P1340 to reset the code. Wait 10-15 seconds and start the engine again.

After this, the engine runs perfectly. I have power, engine responds well to the throttle, no errors or warnings. If I park the car for a few hours and then drive, I have no issues. Park it for a day (go to work, head home after work), I can start the above procedure again.

Thus far I've:
replaced spark plugs
replaced coils
replaced the MAP sensor
replaced the lambda sensor

After every replacement, the issue has gotten better, but still hasn't gone.

I'm currently thinking I need to have my injectors cleaned or replaced. as well as installing oil catch cans.

Now my question to the FOAK is: will replacing the injectors help in this case? Or is there something else that could be the issue?

I figured I'd ask here before spending a lot of money on something that might not be at fault.

Thanks for any replies/ideas!
Chris
PaulC5
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Re: 508 2013 1.6THP Cold start issue

Unread post by PaulC5 »

A quick search on P1340 suggests amongst other things, the cam and crank sensors are out of sync so it could be the timing chain (if it has one) is stretched and needs replacing. How many miles has it done ? We had a C3 1.4 vti petrol and that started giving a fault code at around 50k miles and Citroen diagnosed it as the timing chain but we then changed it for a Cactus at the same dealer so do not know if that was the fix.

If you add your VIN then admin may be able to look up P1340 against your car.
Clutchman11
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Joined: 18 Nov 2024, 10:08
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Re: 508 2013 1.6THP Cold start issue

Unread post by Clutchman11 »

Hi Paul,

Thanks for you quick reply.

The car has done 192k kilometers. The timing chain, and sensors were checked just before Christmas by the local Peugeot garage, and found to be good.

Do I post my VIN here or DM it to someone, as I'm not sure I am allowed to post that in a public post.
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Dormouse
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Re: 508 2013 1.6THP Cold start issue

Unread post by Dormouse »

Just post your Vin. The system automatically obscures Vin numbers so only Forum Admin staff can read it.
Clutchman11
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Joined: 18 Nov 2024, 10:08
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Re: 508 2013 1.6THP Cold start issue

Unread post by Clutchman11 »

In that case: my VIN is: VF3**************[VIN obfuscated, can be read by forum staff]
gwest
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Re: 508 2013 1.6THP Cold start issue

Unread post by gwest »

Really need some live data to back up fault codes. How is the fuel pressure in comparison to reference values? What is the condition of the inlet valves and ports- need inlet manifold partly off and endoscope.
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xantia_v6
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Re: 508 2013 1.6THP Cold start issue

Unread post by xantia_v6 »

I would be checking the airflow vs reference value, on the suspicion that the motorised throttle is sticking.

Under the circumstances you describe, there shouldn't be need for turbo boost, so that system can be discounted.

Our 308 developed a terrible flat-spot from cold which was cured by a throttle reinitialisation procedure (requires diagnostic tool), but yours sounds even worse.
Clutchman11
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Joined: 18 Nov 2024, 10:08
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Re: 508 2013 1.6THP Cold start issue

Unread post by Clutchman11 »

I've been trying to get more information/insight using a generic OBD reader (https://www.scantool.net/obdlink-mxbt/) to read fault codes as well as get data. Yesterday and this morning decided to keep an eye on the fuel rail pressure after the comment by @gwest.

Upon cold starting, the fuel rail pressure remains relatively static at 720-740kpa/7.2-7.4bar, during the whole cold start/stuttering period. Which seems (very) low to me. Once I've done the whole procedure as described in my original post, the fuel pressure climbs to 4900-6000kpa/49-60bar at idle and 6900-7500kpa/69-75bar at constant throttle. Moderate acceleration will see pressures go up to 15000kpa/150bar.

This morning during rush hour traffic (stop and go), after idling for longer than 30 seconds, pressure drops down to 690-750kpa/6.9-7.5bar, but instantly goes to >6000kpa/60bar once you apply throttle.

Now I'm thinking there might be an issue with my HPFP, as a relatively static 7.2-7.4 bar can't be right in my opinion, when driving with a cold engine. I'm just stumped why once the pressure goes up, everything seems fine. Could it be a dirty pump? A stuck return valve when cold?

If anyone has some reference values for the pressures, I can keep an eye on things and compare. Oh and as per @xantia_v6s' idea: could someone also provide the reference values for airflow?
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xantia_v6
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Re: 508 2013 1.6THP Cold start issue

Unread post by xantia_v6 »

This post viewtopic.php?p=788214#p788214 shows a screenshot of the air flow values on my THP 156 engine (probably not cold at the time).