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Peugeot 807 RFN 2008 - Low manifold vacuum, code P1622 & P0105 - Fixed #

Posted by Luke Browne on July 27, 2012, 2:11 pm

Year of Manufacture *: 2008
Engine Size and Code *: RFN
( Optional ) Scanner Used: KTS

Fault codes-
P1622 throttle valve position/ intake manifold pressure invalid ratio
P0105 intake manifold pressure sensor signal improbable
? Camshaft position sensor outside set range

This car originally came in with a shredded cam belt which we replaced with what appeared to be no engine damage ( the belt was on just loose and stripped)
Recently it developed a cutting out issue which was evident for a couple of weeks then nothing? now when stationary there is only servo assistance once due to manifold vacumm between 650 Hpa- 800 Hpa.
There is also a slight misfire when cold which is when the vacumm is at its lowest this we think is due to the ign coil (due to a suspect waveform-pico) and will be replaced shortly. Once warm there is no misfire and the vacumm does improve but not to an acceptable level? No visible air leaks (will be borrowing a smoke machine to make sure) suspected maybe the throttle valve to open what with the faults logged but the butterfly is almost shut at idle and actuator test moves through open to close fine (although a bit jerky?) have checked manifold pressure with gauge and it mirrors actual value with a steady needle.

What kind of layout does the breather have on these, can it leak internally?
Any idea what i should be looking at or a crucial test i've missed. Any info greatly recieved thanks for reading.

Re: Peugeot 807- Low manifold vacumm?

Posted by Alan Lange User icon on July 28, 2012, 10:40 pm, in reply to "Peugeot 807- Low manifold vacumm?"
Alan Lange

Hello Luke, have you done a compression check? (possible bent inlet valve/s) & double check cam timing.

Re: Peugeot 807- Low manifold vacumm?

Posted by Bryan Smith User icon on July 29, 2012, 11:39 am, in reply to "Re: Peugeot 807- Low manifold vacumm?"
Bryan Smith

Hi Luke,
I second what Alan has said re: poss bent valve or incorrect timing (I think the slight misfire is the clue?) but a comp test may not show this very clearly. A cylinder leakage test may give a better result. Whatever it is I am convinced it is linked to the original problem.
If you have a misfire you will almost certainly have a suspect waveform on the ign but if you post the waveform and more details I'm sure someone with better knowledge may be able to pass comment/guide you on that.
HTH's,
Bryan.

Re: Peugeot 807- Low manifold vacumm?

Posted by Luke Browne User icon on July 29, 2012, 9:16 pm, in reply to "Re: Peugeot 807- Low manifold vacumm?"
Luke Browne

Thanks for the replies guys, TIming has been double checked and was spot on, Will check Compression tomorrow and re-post findings ignition coil will be there aswell so will see if it does make any
difference? Would of thought i would have a twitchy needle on my gauge with a bent valve??

Re: Peugeot 807- Low manifold vacumm?

Posted by Luke Browne User icon on July 30, 2012, 10:10 pm, in reply to "Re: Peugeot 807- Low manifold vacumm?"
Luke Browne

Compression test done and did get an unexpected reading.
3 cylinders hit 11 bar in three seconds and maxxed at just under 12, no.1 cylinder (flywheel end) couldnt get past just over 10 bar?
Is this enough of a difference to cause the vacuum issue? Dont have access to a cylinder leakage tester at the moment, may have to invest!

Re: Peugeot 807- Low manifold vacumm?

Posted by Bryan Smith User icon on July 31, 2012, 12:23 am, in reply to "Re: Peugeot 807- Low manifold vacumm?"
Bryan Smith

Hi Luke,
I was always told that up to 25% difference was within tollerance but as I said I don't allways rely on comp test and prefer vac or cyl leakage. As you said in your post, I would probably expect vac gauge needle fluctuations with a valve related problem. Has the new coil been fitted yet? I would also question the code that you have put ? against, camshaft pos sensor outside set range. Is that an historical code from the cam belt shredding or is that a new one?
Regards,
Bryan.

Re: Peugeot 807- Low manifold vacumm?

Posted by Pete Mutlow User icon on July 31, 2012, 8:38 am, in reply to "Re: Peugeot 807- Low manifold vacumm?"
Peter Mutlow

Morning Luke,

From what I understand on this vehicle, it had a cam belt problem and the inference is that it ran perfectly ok until recently. Maybe the cam belt is a red herring? Do the fault codes clear down? What size engine is this thing? What are the exhaust gas readings?

Regards

Pete M

Re: Peugeot 807- Low manifold vacumm?

Posted by Luke Browne User icon on August 1, 2012, 2:03 pm, in reply to "Re: Peugeot 807- Low manifold vacumm?"
Luke Browne

The codes have been cleared after the original work was done so the codes are relevant, also have seen multiple misfire codes and the anti pollution light illuminate first thing in the morning when the vehicle runs at its worst.
After its warmed up the engine seems to run fine just the issue with the very low Vacumm?
Emissions are as follows-
Idle
CO- 0.004%
CO2- 15.38%
HC- 0.00%

Cruise
CO- 0.010%
CO2- 15.40%
HC- 1%

Sorry no O2 at the minute will try and get reading sorted
I am still leaning towards possible valve damage but not confident that this slight damage which dosent appear to cause a running issue when hot, could cause this very low Vacumm?