advice needed please

[Matt-mk2gti]

My 172 ph2 has been playing up recently, first the eml light came on and had misfire got codes read said it was bank 1 sensor1 fault so front lambda so changed that. Eml came on again a week or so later and developed a really bad misfire, codes read again and it was the same lambda fault plus an injector fault so changed the injectors and plugs and leads and coilpack just to be safe.
Now on Wednesday the eml light came on again immediately on start up and has bad misfire/hesitates until up to temp, once up to temp it gets better until it stops misfiring completley, but as soon as temp drops down below the halfway Mark on the gauge it starts misfiring all over again.

The only things I think it could be now are either the intake temp sensor as this doesn't nothing if unplugged but has current running to it, the map sensor but the engine cuts out immediately if unplugged again has currentor the coolant temp sensor but I don't know where it is located or how to best test it.

Any other ideas or pointers would be much be appreciated and apologies for the long thread

 

[KevF182]

My 172 ph2 has been playing up recently, first the eml light came on and had misfire got codes read said it was bank 1 sensor1 fault so front lambda so changed that.

Faulty pre-cat lambda is unlikey to be a cause of missfire IMO. But fiting a new one if history is unknown makes good sense anyhow.

Eml came on again a week or so later and developed a really bad misfire, codes read again and it was the same lambda fault plus an injector fault so changed the injectors and plugs and leads and coilpack just to be safe.

Usual culprits for missfires are the injectors, yes. But you're saying these have been replaced so that should rule that out. Wiring/conectors to them can be an issue so I've heard. What parts did you use? Hopefully new and genuine, but so long as plugs are the correct NGK PFR6e-10 then all should be well on that front.

Now on Wednesday the eml light came on again immediately on start up and has bad misfire/hesitates until up to temp, once up to temp it gets better until it stops misfiring completley, but as soon as temp drops down below the halfway Mark on the gauge it starts misfiring all over again.

Now this makes me wonder if you're cooling system is working properly. Once up to temp on the gauge it should not drop again. No matter how its driven. If the gauge is showing fluctuations then often its the thermostat (or its seal) that is faulty. This wouldn't in itself cause a missfire though. However, although less common, the coolant temp sensor might be faulty. I've no experience of faulty CTS causing missfires on clios (but I have on other cars). More typically its an idle/pickup issue as its often running rich, rather than a full-on missfire though.

The only things I think it could be now are either the intake temp sensor as this doesn't nothing if unplugged but has current running to it, the map sensor but the engine cuts out immediately if unplugged again has currentor the coolant temp sensor but I don't know where it is located or how to best test it.

Any other ideas or pointers would be much be appreciated and apologies for the long thread

You'd be well advised to get in on propper diagnostics not just a code reader. You need to see the live data to determine whats what, what signals the ecu is receiving etc. But if your wanting to do some investigating yourself then you could try and work out if its a single cylinder missfire and which particular one (as is often the case). This then makes it easier to identify the cause if your'e only dealing with one plug/lead/injector etc.

Kev

 

[KevF182]

double post

 

[Matt-mk2gti]

Sorry I mean temp gauge drops down past halfway as in I switch the car off to let the engine cool then go back and restart a few minutes later