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THP Petrol engine puzzling problem

33K views 59 replies 7 participants last post by  noddy-hol 
#1 ·
Hello all,

We would appreciate some help please.

We have a 308, petrol, 1.6 THP, with a problem that is puzzling our local garage. It is having an accelerator or throttle control problem. It is only noticeable in a stop and go situation: when the car is stopped, just before starting to move, a driver 1st presses the clutch down, engages 1st gear, but when the driver's foot touches the accelerator (before lifting the clutch) the reaction from the engine is not smooth, it's a bit erratic, oscillating "around" what the driver intended, in little “bursts” of around 1 second each, like when a driver is revving the engine a bit, but I am not, my foot is still.

Notes: The idle is fine. And when the driver puts its foot down the car goes very well, with its normal 0-60 below 9 seconds.

Our local garage said that it could be many things, if I remember correctly: the sensor behind the accelerator pedal, or some other sensor on the engine side, or the wire in between them, or some “throttle control”? (or some “butterfly” in it?), or perhaps a software problem?

But they had no way of knowing before starting to replace parts, which could be expensive, and wasteful. So I thought perhaps you guys in this Forum may have seen this problem before in other THPs? Or could suggest some tests, or questions, to narrow down the possible problems please?

Thank you all in advance for your help,

Mark
 
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#6 ·
Hi jimmymarsbar,

My local garage has the Peugeot/Citroen software, but there were no error codes. But they did suggest that I took the car to a Peugeot dealership garage anyway, for 2 main reasons:

1) Perhaps they have seen this problem before on a THP engine;

2) They could check if there were software updates for my car (because only Dealerships can check for that now).

I did that, explained the car problem at the reception, in details, like I've done above here, the receptionist even asked me if the idle was ok, I replied that yes, the idle was fine. And I asked them to check if there was a software update available for my car.

When I took the car back the paper work said that the mechanics had investigated 2 problems:

1) "Erratic idle"

2) "Car not driving smooth"

Point 1 was very annoying indeed.

And in point 2 the reception summarised too much my explanation, not pointing the mechanics more precisely towards the problem.

And they have not checked if there was a software update for my car.

Conclusion, I'm going back to my trusted independent garage, probably starting by what them and Sinisha (above) think is the most probable cause, the throttle control.
 
#10 ·
Hi ADS77,

Yes, that was the standard Peugeot Dealership recommendation for the error code - to open the engine and clean the valves. The problem is, my local mechanic said that if it were the valves the car would have loss of power, specially at higher revs, and the car power is fine, 0 to 60 in under 9 secs, as expected.
 
#11 ·
Depends if wanna go with local mechanic or get the issues sorted properly.

I don't work for peugeot myself but very experienced in the thp engines as deal with them on the 207's and those are very common issues now.

U don't need open engine up to clean the inlets, there's a couple of ways to do it apart from stripping it all down and taking the head off.

Sent from my SM-G925F using Tapatalk
 
#12 · (Edited)
Very good news that we don't need to open the engine up. Thank you very much for that. The dealership wanted to open it, and quoted around £1.5k to do it! our car is a 2008, not sure it would be worth doing it...

The local French specialist garage is very reputable, even the Dealership said so. Actually the independent is more experienced than the mechanics currently working at the dealership. The Dealer has the advantage of connecting its laptops with Peugeot, but the disadvantage of having receptionists intermediating the communication between the car owner and the mechanics - BIG problem.

About the car power being fine, doesn't that excludes the carbonisation issue?
 
#14 ·
Even the dealership told me that the independent French car specialist is a very reputable garage. I think its better to leave names out of a public thread, better to focus on the mechanical issue itself.

Good to know that only the master techs would work on the THP engine, pity that he hasn't received the full or even correct description of the car problem. The receptionist summarised it too much and even mislead him regarding the idle. And he doesn't know either that the car power is fine.

By the way, doesn't that (normal power) eliminates the possibility of "carbonised cylinder head and valves"?

Based on the 2 fault codes alone, the dealership recommended: "clean/ decarbonisation of cylinder head and valves, zero reset and programming of the auto adaptive values and replacement of the engine oil and filter after a full road test."
 
#16 ·
Thank you very much for all that info ADS77.

I agree that I would not notice a small loss of power.

About "walnut blasting" and 4hrs job: IIRC (and II understood C) I think both the dealership and my garage were estimating more hours than that, I think some 10hrs, or at least a full day, as they were quoting some £1.5k at the dealership, and £1k at the independent. I noticed that the dealership recommendation includes cleaning not only the valves but also the "cylinder heads". Is that the difference between what you and they are saying? Would that require to open up the engine, and therefore be more expensive?

Thanks again, (and sorry to bother you with more questions)
 
#17 ·
The walnut blasting according to Peugeot is "Cleaning of an inlet duct and of the associated valves"

So goes thru the ports where inlet manifold is situated and cleaned from there.

It will get 99.9% of the build up removed but only way make sure the spotless is by removing the cylinder head and removing them to clean them, that's where the excess money will come in in terms of the labour to remove the cylinder head and then u got the cylinder head gasket which is like 90 quid or something, new bolts etc etc
 
#18 ·
Thanks again ADS77,

So when they estimated £1.5k they were probably planning to go for the whole thing, instead of the "walnut blasting", right?

Why would they do that? Just to charge more?? That's would be really cruel. (My car is a 2008, bought used, and they know we are a family on a tight budget, with a toddler, etc.)

Perhaps they don't have the equipment for that walnut blast? But even if this was the case, they could/should have said so, and referred me to whomever offers walnut blasting.
 
#19 ·
Sounds like a dealer being a typical dealer unfortunately.

Personally, the walnut blasting will do just as good a job, cause with the car being DI and the PCV set up, after another 10k miles the inlets are gonna have a good covering of carbon and oil deposits again.

Would rather pay say £400 for basically the same job as £1500 !

You could be correct on the dealer not having the equipment, for example when I had engine rebuild my local dealer who I trusted completely and had friends working there, didn't have the tools or equipment there to rebuild the bottom end of the engine, they would normally just replace it like for like!

So my 207gti went to a French specialist who's mechanics were all former Peugeot techs and master techs. Unlike one "French specialist" who I understand a couple of years ago talking to various sources in the car scene, isn't a trained Peugeot tech/mechanic but gets all their tools and tech info from family member who runs a Peugeot dealership..........
 
#20 ·
I was Googling about walnut blasting, trying to find garages that do it, prices, etc., and came across a list, from a BMW Mini forum (they have the same THP engine). It's a bit old, from 2013. Interesting to see the wide price variation, from £200 to £400:

Walnut Shell Decoke Garages

Not sure if BMW Dealerships would work on a 308 though.

Perhaps there are similar lists for Peugeots. Or independent garages that offer this service.
 
#25 ·
I've just tried to PM you but got this message:

"Sorry, you can only send messages to the Administrators group until you have 20 posts."

So, I'll try to post a few more messages (well, 4) after lunch (probably in the Off-Topic section), and PM you afterwards.

Cheers,

Mark
 
#27 ·
Update: My THP needs de-carbonising, but my local Peugeot dealer doesn't have the walnut blasting equipment, and would charge me over £1k to do it manually, opening up the engine, etc. Googling I found a Peugeot dealer on another city that has the walnut blasting, phoned them, but to my surprise they quoted a very similar amount! Over £1k! Is this right??

If that price list from BMW dealers I posted before is correct this Blasting thing should cost from £200 to £400! What is going on??

Cheers,
 
#28 ·
They say it's 4 hours job the walnut blasting from info I have on service box.

The manual is a fair bit more labour involved as be totally stripping the head down.

But terraclean now do it for DI engines like the thp and it's like 100 quid or something like that am sure, a peugeot dealer in Bristol I know use them when they need clean the inlets and not need to strip the head down.

Sent from my SM-G925F using Tapatalk
 
#29 ·
Hi ADS77,

Exactly, if manually is so much more labour intensive why did the Blasting dealer quoted me almost exactly the same amount? Actually a few quid more!

There was one thing that made me a little suspicious: The 2nd dealer asked me if I had had another quote, I just said no (because I hadn't - for walnut blasting). Then they asked me for my car's Reg, and my phone number (with my area code, from my town, and we have a Peugeot dealer here, so he may have thought "why is he phoning us ?) A few hrs later they phoned me back with the quote.

Later I thought: Could Peugeot have some database where he could have found the 1st quote (using my car's Reg), and due to some "no undercut another dealer" rule he quoted me above the 1st one??

Am i being paranoid here??
 
#30 ·
Sorry, I forgot to reply about Terraclean. Yes, I found them a few days ago, did some research about it, and ended up unsure, because about Direct Engines their website FAQ says:

______________________________________________________
"Q17: Will TerraClean work with my petrol Direct Injection engine.

A standard TerraClean service does not touch the Intake on a DI engine. But there is an adaptor tool the service agent can use to clean Intake and there is a specific Petrol Induction tool whcih many of our agents have specifically designed to clean this part of a Direct Injection system. Simply talk to the agent when booking the car in about your requirements."
https://www.terraclean.co.uk/faqs
______________________________________________________

I thought that was a bit evasive: "many of our agents have specifically designed" = like, not us gov...

And for DI engines it would involve 2 different jobs, and would cost about £200.

And some people ask why Terraclean doesn't show pictures, "Before/After" type.

A YouTube video about a similar method (chemical, through the air inlet) says it cleaned about 25% of the gunk.

Another poster worried about the dislodged "gunk" then going throught the engine and catalytic converter.

I had Googled: review terraclean direct engine
https://www.google.co.uk/search?q=review+terraclean+direct+engine&ie=UTF-8
 
#31 ·
Don't believe have database where can beat other garage quotes as they are all individual franchises.

Terraclean do have ability to do DI now and lad up here for quoted 108 quid am sure.

As for the labour part, walnut blasting just does the work with the machine but obviously uses a work bay, while the manual clean is proper mechanic labour lol

Sent from my SM-G925F using Tapatalk
 
#32 ·
Thanks ADS77,

All good news.

I'll phone a Terraclean near me, let's see what they say.

Very good point re. labour for blasting. Which makes the £1k+ quote even more puzzling. It does not make sense. I should phone them again, and ask for a justification, but frankly... i'm very tired of all this malarkey.

Thanks again,

Mark
 
#36 ·
Hi ubdevoid,

Thank you for that. Not silly at all! Some months ago a mechanic said that it could be the software preventing the car from stalling. I didn't take him seriously, cos it happens all the time, and the car was not stalling. Now that you mention software... could well be some software malfunction. I'll pass your suggestion to my mechanic.

Thanks again,

mcf

(PS: apologies for my delayed reply, we have a toddler!) (For the non-parents, this means we are very sleep deprived, exhausted, confused and disorganised!)
 
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