Idle problems

[Lakeman]

Hello guys,

I have a problem with my 172 ph1. The idle is very lumpy and I can hear it misfire sometimes. It is having a little 'puf' at the exhaust sometimes when idling. Also it doesn't run good till 2k rpm. When you accelerate you have a little 'bump'. Changed the TDC sensor, an other coil pack (from other clio), spark plugs, lambda sensor, leads (magnecor blue). It runs fine from 2k rpm. What could it be???

Thanks.

 

[MicKPM]

Well really, the best place to start would've been a reliable diagnostic session but you're a bit past that now lol. Most likely problem you have here is either an Injection issue (poor injector or injectors) or possibly a supply pressure fault. Then there's the good old fashioned "your timing is wrong" subject but seeing as you've changed just about everything else on the Ignition/Injection I'd whack a set of injectors in.

If it were one of my customers vehicles though, I'd start with the quick and simple electronic checks followed by physical checks of fuel pressure, compression and finally a timing check.

Mick

 

[Lakeman]

And what about map sensor?

 

[MicKPM]

What about the MAP Sensor? Have you checked its data stream to see if the value is stable/probable (Eg. is it reporting a correct "Atmospheric" reading when the engine isn't running Vs showing vac when it is... is it reporting anything at all?)? No, this is why we normally advise a live data session on decent diagnostics before you start guessing and swapping bits.

Mick

 

[Lakeman]

Did a live data session. When idling it is saying 500 mbar. Sometimes it drops to about 50.

 

[MicKPM]

"Sometimes" as in when it's about to stall?

 

[MicKPM]

What was the reading with the engine off? It should be stable at around 1013/1014Mb

 

[Lakeman]

Correct.

 

[Lakeman]

1073 mbar atmospheric pressure it was reading.

 

[MicKPM]

Timing issue then chap - plugs out, pin the crank and insert the camshaft setting bar... I bet you can't get it in.

 

[Chrisgti6]

I came into this thread expecting it to be about my wife - she has an idle problem too.