406 xu7jp4 wont start

[skyclad]

I've now convinced myself that the cambelt is OK So lets go back to basics.

My Pug started doing an erratic tickover thing. Normally runing ok no problems but occasionally it just refused to idle. When it did this I noticed when I turned off the ignition a whirring noise came from the throttle area and then when I started it again the idle would be ok.

I came out last thursday morning to start the car and it fired, stalled (no idle) then just refused to start at all. Took out the plugs (wet) checked the coil pack (sparks). I suspected the timing belt as it sounded very weak when turning the engine over (just a hunch) but I'm not convinced now, so I've left it alone.

Any suggestions or do I have to get a Pug person and their little computer...

Its a 406 97 XU7JP4 1.8 16V engine

[jgra1]

hi skyclad

the buzzing is almost definately the idle control valve.... and I would think that item is your first port of call for getting the car back to normal

remove and clean it first off I would say. to be honest it's one of the many parts of a car I have had little to do with.. but it does seem to give a few problems when it gets sticky or dirty

John

[skyclad]

Cheers John. I will give that a go 2mor..

[CitroJim]

I suspected the timing belt as it sounded very weak when turning the engine over (just a hunch) but I'm not convinced now, so I've left it alone.

This worries me. Are you saying the engine now sounds different when it is cranking over?

A broken cambelt usually makes the engine turn rather more freely on the starter and they can sometimes spin so fast that they make a whirrrrr rather than the normal urgh-urgh-urgh sort of sound.

Fact is, if you have sparks and fuel then all other things being equal, it should do something. Having said that, the mixture does not need to be far away from too rich or too weak before starting difficulties will be noted and there's nothing to say the sparks are occurring at the right time.

A diagnostically equipped person may be most valuable to rule out things like duff coolant temperature, MAP sensors and so on - both the former can wreak havoc with starting and idling...

I'd slip off the timing belt covers though, just to put your mind at rest.

[skyclad]

Stripped down the throttle housing. Checked the sensors stepper motor, throttle position etc. Apart from being covered in oil all seemed fine. Took out the MAP and that was covered in oil as well. Would this cause it to stop the engine firing? Cleaned everything and checked the wiring pipes etc. Will put it all back shortly.

[CitroJim]

Took out the MAP and that was covered in oil as well.

It could certainly make the car idle very poorly and by extension make it very hard to start...

Give it a good dose of carb cleaner, this sometimes crevives a sad one...

[Chris570]

I can only go on what i've heard here but i've heard that carb cleaner and MAP sensors don't mix well.

don't ask me why, i don't know, just going on hearsay

[skyclad]

IT LIVES!! Sorry I had to shout that.....

My conclusion.

Sump relief blocked with gunge in the throttle body causing MAP to fill up with oil??

Bloody good clean sorted it.

Thanks fellow French Freaks Tre Bon

[CitroJim]

IT LIVES!! Sorry I had to shout that.....

Brilliant I'd shout it too but I'm at work so must be quiet

[skyclad]

I used a plastic friendly solvent cleaner (chris570). You have to be carefull with this modern plastic built crap... I'll let you know if it disintegrates LOL.

[Chris570]

good good

if in doubt i prefer to err on the side of caution, especially with our french cars as they usually show their displeaure by doing something expensive