Any pointers on my 405 idling problem?

[carlo]

Morning gang.

 

Has anyone got any suggestions as to where I should start looking for this problem with the 405?  For a couple of months now it has had a very intermittent idling/cutting out problem.  It can be when the car is hot or cold, or if the fuel tank is full or nearly empty.  It may be fine for a week, then suddenly it will not idle and you have to keep re-starting the car constantly.  During this behavior the car feels lumpy and the throttle jerky.  Occasionally when it is playing up it will nearly die, the STOP light comes on but will just about recover and creep back to about 500RPM, eventually getting back to its usual idle speed of about 900RPM.  Unfortunately seems to have deteriorated this week and has been very bad for two days on the trot.

 

Engine is the 8v 2.0 petrol (it's an auto).  Am going to take it down the local garage Monday but sod's law it will be behaving perfectly then and it's too old to plug in to any diagnostic equipment apparently.

[John F]

There'll be a 20p lodged somewhere, it's a common fault with old Peugeots...

 

More seriously: check / replace air filter, it's worth replacing the fuel filter if it hasn't been done for a while... and if that doesn't help, check MAF / idle air control valve... possibly lambda sensor, although unlikely.

[Sigmund Fraud]

That generation of Peugeots had frequent problems with the MAP sensor, often all you need to do is take it out and clean it.

[carlo]

So it has a MAF and a MAP sensor?   MAP one sounds possible.

[beko1987]

There'll be a 20p lodged somewhere, it's a common fault with old Peugeots...

If there's not one in the handbrake mech then put one in immediately, should fix it...

 

A good service might help, the xm used to get grumpy when it wanted a service!

[twosmoke300]

Manifold VAC leak I reckon . check all the VAC and breather pipes . or when the engine is still cold ish spray some brake cleaner around the area and see if the engine note changes

[carlo]

Sorry I'm no mechanic, what's a VAC leak?

[Sigmund Fraud]

So it has a MAF and a MAP sensor?   MAP one sounds possible.

 

Not sure what injection system those came with, could be either... If you have an HBOL, you should be able to work it out.

[Sigmund Fraud]

Sorry I'm no mechanic, what's a VAC leak?

 

Vacuum, presumably ?

[Junkman]

I had the same. One of the vacuum tubes came off the MAP Sensor, which is underneath the front panel, near the bonnet catch.

Push the tube back on and happy days.

[Andrew353w]

If it's the same engine as I have in my Xantia 2 litre automatic I know what you're on about! Mine did that a few times recently but after a full service (including a fuel filter change) and a good belt round the M25 it's been much better! Maybe it was the belt that did it... Solid engines otherwise!

[Conrad D. Conelrad]

Here are the photos of the sensor Junkman is referring to:

 

For context, the sensor is in the centre of this photo.

[carlo]

Many thanks for all the input, good pointers there

[carlo]

There'll be a 20p lodged somewhere, it's a common fault with old Peugeots...

 

More seriously: check / replace air filter, it's worth replacing the fuel filter if it hasn't been done for a while... and if that doesn't help, check MAF / idle air control valve... possibly lambda sensor, although unlikely.

 

Looks like it was indeed the idle air control valve!  Remembered I had a spare throttle body in the barn (barn find?), so swapped the IAC and bingo, revs rise to normal levels when you start it, and it idles beautifully with no cutting out.  Cheers!

[John F]

Woohoo! I win... er, nothing