[Peter.]

Hi folks,

I had some great help here and now I've figured out my login details I'm back again with a doozie.

My daughter's car suddenly started running rough on idle and displayed "Depollution system faulty" on the screen when it started. I checked the code with my basic ODB2 scanner and it gave P1340 which the scanner claimed to be "cam position sensor B circuit malfunction" but I've since found in a search that on a Peugeot it indicated misfire on cylinder 4.

Car is a 2008 Peugeot 207 1.4 petrol with 75k miles on it. Vin No is VF3WA8FSC34510971 Starts OK, but has rough idle, turns very rough with a tiny bit of throttle (off-load) then clears as you rev it a bit. Gets worse as engine warms to the point that it will sometimes stall.

So today I have done the following:

Fitted all new plugs
Checked that the coils are all firing. They do with a half-blue half-orange spark (using one of the old plugs)
Swapped stick coils on no3 and no 4 over for empirical testing purposes.
Stripped out the fuel rail and set the injectors up in my workshop with 45psi air pushing a long pipe full of brake cleaner. Fired each one in turn with a 6v battery and they all fire with identical patterns, no dribbling etc.
Swapped injectors for cylinders 2 and 4 for empirical testing purposes.

Put it all back together and it's no different. Same OBD2 fault code.

Just in case I swapped the A and B cam position sensors over and got the same error.

Un-plugging the cam position sensor gives a different error.

So now I am lost for what to do next and looking for some more wonderful help.

Pete.

 

[RedSector]

PEUGEOT 207 1.4 VTi 16V EP3 (8FS) with P1340 Fault Code 'Cylinder 4 misfire detected'.

Possible causes:-
(1) Hall/MRE sensor on the inlet camshaft
(2) Hall/MRE sensor on the inlet crankshaft
(3) Injector 4
(4) Ignition Coil 4

To Diagnose
(1) Hall/MRE sensor on the inlet camshaft

(2) Hall/MRE sensor on the inlet crankshaft

 

[RedSector]

(3) Injector 4

(4) Ignition Coil 4

If you are using basic OBD2 scanner, more than likely there are other codes available not being displayed. I recommend you use Lexia3 or equal device, and they are not expensive if you own a laptop under 10 years old and will provide complete diagnostic information.

 

[RedSector]

This is a bit of a guess (based off your initial post), specifically the message 'Depollution system faulty', but I think that the catalytic convertor maybe partially blocked and you should investigate / clean it. There are products you can spray in to aid cleaning and leave in-situ. And it is likely, unless the scanner claims differently, it will not pick up the code(s) present for the fault(s) for this.

Peugeot Planet - buying, installing, using | Peugeot Forums
Diagbox 9 (VM) install Guide | Peugeot Forums

Hope you find this helpful.

 

[Peter.]

Thank you so much for the time you have taken on this.

I would never have believed this but the issue is actually zero compression on cylinder 4. I managed to borrow a compression tester this morning or I would have checked it sooner. I guess it must have popped a valve or something for it to happen in an instant but at least now I know where the issue lies.

 

[Peter.]

Safe to say I've foud my fault

 

[Brass_Munky]

Safe to say I've foud my fault

View attachment 104337

You got that head off quickly based on the times on your posts!

I've only ever taken the heads off motorcycles but have never seen a deposit like that. Are those the intake valves that are covered in that gritty looking deposit?

 

[Peter.]

You got that head off quickly based on the times on your posts!

I've only ever taken the heads off motorcycles but have never seen a deposit like that. Are those the intake valves that are covered in that gritty looking deposit?

Well I started stripping all off about 11am done about quarter to 5 just in time for roast beef dinner. It was a bit of a marathon but I got work tomorrow and I wanted to get bits ordered. The hidden bolt down the back of the head confounded me for a bit, as did the bottom support bracket bolt for the inlet manifold and the exhaust manifold studs are a sick joke for being so long. They'll be getting chopped down before it gets re-fitted.

The deposits are pretty normal. This cylinder is darker/wetter than the other three because it's not been firing just pumping fuel/air mix.

Plan now is new check the seat isn't damaged, new valve, lap all the others, new head gasket, cam chain kit and put it all back together.

 

[RedSector]

The valve seat looks damaged (as well as the valve). Are you going to repair or use donor head ?

 

[Peter.]

The valve seat looks damaged (as well as the valve). Are you going to repair or use donor head ?

No, the valve seat's good.

Head is all stripped, ports de-coked, valves de-coked. Just need the new valve now then lap them all in, lap the head flat and rebuild it.

 

[Brass_Munky]

I'm still in awe of how quickly you are progressing this. My workshop is far to cold to make me even want to venture in there at the moment. I understand lapping valves in, but lapping the head flat is new to me. Do you mean get it skimmed or something else. I'm always keen to learn something new, especially if it means avoiding skimming a head.

 

[Peter.]

Well I'm in the workshop now but I did all this work in the street as I have no off-street parking.

Lapping the head is done with a cast iron plate which is charged with lapping compound. I have one that I know is flat to better than 1/100th of a mm I use it for reconditioning granite surface plates. It's a bit of a specialist thing that I do as part of my hobby but it's not difficult. If you do a search for cast iron lapping plate you'll find examples. They are just a flat cast iron face with grooves cut into them.

A typical 4-cyl ally cylinder head will probably be in tolerance if it's flat to within 2-3 thou (0.5-0.75mm). Skimming should comfortably achieve 1-2 thou overall flatness (the factory new finish will be much better) whereas lapping will achieve half a thou without trying and better than a couple of tenths (0.005mm) with care.

 

[Peter.]

Getting ready to rebuild this head today despite being full of flu

I could do with the tightening torque info for the head bolts, and the re-assembly sequence for the VVT unit, if anyone can help please.

 

[RedSector]

torque info

See if this is helpful. 1daNm = 10Nm

 

[Peter.]

Yes that couldn't be more helpful thank you.

Pete.

 

[Peter.]

Valves lapped, head also lapped ready for re-assembly

 

[Peter.]

Had to make an adapter for my valve tool to reach deep into the head. This is the last valve getting installed. I used some cable ties to keep the hydraulic lifters in their proper places. There's 2 that you can't secure but they are at opposite ends of the head so if they fall out it's easy to see where they came from.

 

[RedSector]

I bought ones of these about 15 years ago, still love it
36050 Valve Keeper Remover and Installer Kit w/ Valve Stems - Car Repair Tool | eBay

 

[Peter.]

I did it the hard way, mind you I hate working on cars and wouldn't even have done this on my own so I don't expect to be doing valves again anytime soon. But you know, it's my daughter's only transport and she relies on it for work besides she has our car right now so I have a good incentive to get it done

Head is rebuilt and ready to be re-fitted. The weather is very sour for the next few days so it's looking like a next weekend job.

I'd like to be introduced to the guy who invented that spring-loaded VVT system. I'd walk straight up and shake him

 

[RedSector]

Looking good to go, you got this done efficiently, hopefully the weather turns good for long enough soon.