308 THP hesitation on throttle

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walkingperson

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Tadpole
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Jun 9, 2017
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Location
Melbourne
Hiya, my 2012 308 THP has developed a hesitation on throttle this morning. From a standstill, it's almost like it's just rolling for a few seconds before it will pick up - and sluggish even then.

No CEL or anything on the dash, I'm thinking fuel starvation of some sort? Fuel filter? Injectors?

Next thought is plugs or coils but I would have thought I'd get some sort of communication from the vehicle if that were the case.

Just wondering if anyone here had a similar experience or whether there are any common THP that issues of this sort after about 110,000ks.

Car has had timing chain done (twice) and new turbo so I can hopefully rule those out!

Any thoughts appreciated.
 
Does it misfire? Have the inlet ports ever been de-crudded?
 
Was it an overnight event and now constant?.


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Thanks Seasink, the service records show a dealer inlet port decrud at approx 80k (from memory - will check when I get home) it has always had (what I thought) a slightly uneven idle but misfire, no I don't think so.
Nagaman - literally just started today halfway through a trip. Car was absolutely fine pulling up to the lights, I went to set off, and the problem started and persisted.
 
walkingperson said:
Thanks Seasink, the service records show a dealer inlet port decrud at approx 80k (from memory - will check when I get home) it has always had (what I thought) a slightly uneven idle but misfire, no I don't think so.
Nagaman - literally just started today halfway through a trip. Car was absolutely fine pulling up to the lights, I went to set off, and the problem started and persisted.
Click to expand...

Well the crud thing would be incredibly incremental so injectors with bad fuel from last fill perhaps.


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So the problem has returned and I now learn it's accompanied by a hiss coming from (around the area of) the first injector, near the oil filler cap. The sound runs on after the engine has stopped.

After a chat with my Dad and a bit of reading I bought a back pressure tester as the car is not losing coolant, as far as I can see. So we suspect a clogged catalytic converter or exhaust.

The back pressure tester won't register anything at all, even with the engine revving to 4500rpm. I have a feeling it's a faulty unit as you can hear it rattling as the engine is running.

Surely I should be getting some sort.of reading if it's functioning correctly?
 
You need to replace the rocker cover the pcv is gone that will also cause hesitation


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Thanks DMC, after reading your post I found this other thread
Peugeot 308 EP6 1.6 THP revised valve cover design?

Sounds like that's what it is. So the PCV is integral to the rocker cover, correct?

Is there any major advantage to the newer design of cover over the old? I just replaced the turbo pipe last Christmas when replacing the bung turbo and I'm hesitant to replace that pipe again since it's less than a year old!
 
Check fuel rail pressure. If it’s below spec which happens often it’s likely it needs a new high pressure fuel pump. They only usually last around 100”000km. Rough idle or flat spots are usually the start of the issues. Then it will
Progress to rough running on cold start.
A decent scan tool will tell u rail pressure.

After market pumps work well and only a few hundred bucks.

Pcv system also has a blank off kit available
To delete the rear breather / pcv. Reducing amount of oil vapour being sent to the intake system.
 
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