Misfire and Fuel Trim Malfunction

[HammieGB]

I have a 2003 Peugeot 206cc 2.0l. I've had a few problems with it since I bought it, the biggest being a Cambelt and a faulty injector that I have replaced. Car runs a bit better than at first but still barely any power in second through low rpm. I also have a catalytic converter fault after driving for while, followed by a peep and car going into limp mode. Now Last week I took it for a look at the cat and sensors and a diagnostics test. Exhaust, Cat and 02 sensors seem to be working fine.
Diagnostic Report is as follows.
P1336 - Misfiring
P0300 - Random / Multiple Cylinder Misfire
P0170 - Fuel trim Malfunction Bank 1
P0326 - Knock Sensor Circuit Range Bank 1

I have replaced a faulty injector and spark plugs previously, so I thought it might be the coil pack, but have no real way to test it as I can't disconnect it coil by coil and only the whole unit. I have no idea where to start looking, and have spent enough money on this car already to just give it to a mechanic and have him fiddle away for hours and find the problem, charging labor as he goes along. I love it for the short while this car works properly, but hate it when it just cuts out and I have to pull to the side of the road before it decides to cut out. Any assistance would be greatly appreciated.

[Capncol]

The issue seems to be caused by fuel trim. My guess is you have an air leak on the inlet causing an overly lean condition possibly causing pre ignition (misfire) and triggering the knock sensor. Start by listening for a hissing around the inlet area and associated pipework

[IanL]

If you can't hear the hiss, try this when idling:

One way of searching for the leak is to use a volatile inflammable vapour - spray it sparingly around the various pipes which connect to the inlet manifold. When it is sucked into the manifold the mixture will be enriched and the revs will rise. Carburettor cleaner spray should be suitable, but any alcohol-based spray cleaner should work.

[HammieGB]

The issue seems to be caused by fuel trim. My guess is you have an air leak on the inlet causing an overly lean condition possibly causing pre ignition (misfire) and triggering the knock sensor. Start by listening for a hissing around the inlet area and associated pipework

Thanks for the advice. I did read it might be a leak in the manifold, unmetered air passing through the air filter or a stuck open EGR valve, but have no real idea how to look at these. Will have a look see and let you know what I find.

[HammieGB]

If you can't hear the hiss, try this when idling:

One way of searching for the leak is to use a volatile inflammable vapour - spray it sparingly around the various pipes which connect to the inlet manifold. When it is sucked into the manifold the mixture will be enriched and the revs will rise. Carburettor cleaner spray should be suitable, but any alcohol-based spray cleaner should work.

Will check if we have some in the shed, might help to pinpoint exactly where the leak is coming from.

[HammieGB]

The issue seems to be caused by fuel trim. My guess is you have an air leak on the inlet causing an overly lean condition possibly causing pre ignition (misfire) and triggering the knock sensor. Start by listening for a hissing around the inlet area and associated pipework

Thanks for the advice. I did read it might be a leak in the manifold, unmetered air passing through the air filter or a stuck open EGR valve, but have no real idea how to look at these. Will have a look see and let you know what I find.

Okay I opened the bonnet and started the car and heard a very distinctive hiss coming from somewhere around the right and hand side of the engine it seems. Can't really pinpoint where with all the engine noise though

[Capncol]

Use a length of tube as a stethoscope. One end to your ear and use the other end to pinpoint source

[gazza82]

Okay I opened the bonnet and started the car and heard a very distinctive hiss coming from somewhere around the right and hand side of the engine it seems. Can't really pinpoint where with all the engine noise though

Take the engine cover off and check the black oil vapour pipe on the right of the engine. They get brittle and snap .. as a temporary fix I jammed the two ends in a piece of rubber pipe and that's lasted nearly two years!

[HammieGB]

Okay so I'm checking for maybe a vacuum pipe leak, as I'm not getting anything on the manifold. Just something I noticed yesterday, and don't know if it's just the management system trying to compensate for extra air, but when I open the oil filler cap it has a distinct petrol smell to it.
It's a pity you can't upload videos to the site, showing the knocking of the motor and to hear the leak.

[gazza82]

You could put the vid on youtube or a similar site and add a link to a post here ...

[Capncol]

Okay so I'm checking for maybe a vacuum pipe leak, as I'm not getting anything on the manifold. Just something I noticed yesterday, and don't know if it's just the management system trying to compensate for extra air, but when I open the oil filler cap it has a distinct petrol smell to it.
It's a pity you can't upload videos to the site, showing the knocking of the motor and to hear the leak.

Did you try the length of hose trick? Did you check around all the inlet and associated pipework? (including servo)

It's a pity you can't upload videos to the site, showing the knocking of the motor

Bit worried by this. Are you saying it's knocking while idling?