Diesel erratic idle in cold weather

dak

I have a 4 year old Renault Grande that developed an issue after the last service. Garage have not resolved the issue yet

Car starts on first go , revs stay at 1000 rpm for a few minutes and then drop to around 800 and return to 1000 rpm . Car has cut out on 1 or 2 occasions but more times than not it recovers having nearly cut out. Once warmed up idling is fine and doesn't fluctuate

This only happens during a cold start. Garage have said they have checked all sensors , thermastat, cam sensors etc and no faults coming up on diagnostics. Battery was replaced also. Also upgraded fuel injection software.

Garage put Diptane in tank and asked that I drive it for a week to see if it improves . Its improves slightly but still is a bit rough until warmed up?

I have a 5 year warranty but on the last bill I got from them for the battery they put a note to say these additional tests would be chargable .

Any mechanics here come across this issue before. Garage said if issue persists then they would do a diesel pinking test and test the solenoid.

Is this a sensible test and has any one have any idea of what might cause this cold start issue ? No perceivable lost of power occurring even when cold !

Veloce

dak - did the garage check the MAF sensor? (airflow meter)

martinr5232

Did they test glow plug circuit sounds to me like glow plug fault or a coolant temp sensor fault.

Caliden

If it's only cold starts it could be something to do with glowplugs.

dak

Veloce wrote: »

dak - did the garage check the MAF sensor? (airflow meter)

They said they did

dak

martinr5232 wrote: »

Did they test glow plug circuit sounds to me like glow plug fault or a coolant temp sensor fault.

There is no issue with the actual start so unlikely to be glow plugs. It starts first time all the time. I though it might be the coolant temp sensor myself but they said that no faults showing up on diagnostic equipment.. its a main dealer doing the testing!

dak

Caliden wrote: »

If it's only cold starts it could be something to do with glowplugs.

The car starts on one press of the starter motor first time hot or cold so I dont think that would indicate glow plugs

zwind

egr/dpf will cost rough idle as well.

GTDolanator

would the idle need to be set slightly higher maybe?

the merchant

I seem to remember that the glow plugs on these can run for a while after the engine starts. I'd put money on it being a glow plug or two.

kenmccarthy

Definetely sounds like glow plugs-had exact same problem with a 10 qashqai......ended up being the glow plugs

martinr5232

dak wrote:

There is no issue with the actual start so unlikely to be glow plugs. It starts first time all the time. I though it might be the coolant temp sensor myself but they said that no faults showing up on diagnostic equipment.. its a main dealer doing the testing!

Glow plugs are not really used for startup anymore with common rail direct injection they are more for emissions.

visual

Take out the egr valve and clean it
From past experience Renault main dealers are unbelievable poor with their own products.
For advice on Renault go to Renault forum UK the lads on there know their stuff

Caliden

dak wrote: »

The car starts on one press of the starter motor first time hot or cold so I dont think that would indicate glow plugs

So did mine but it also idled like a dog for 3 minutes until I replaced 2 glowplugs last year.

dak

Hi Caliden

Was your car a 1.5 DCI Renault ?

Thanks
Dak

gctest50

some glowplugs are also pressure sensors :

Caliden

dak wrote: »

Hi Caliden

Was your car a 1.5 DCI Renault ?

Thanks
Dak

No it was a bmw 120d. Idled very rough and a good bit of smoke on cold mornings.

bear1

Possibily a failing fuel filter. With the colder weather diesel can get a bit more gelly like which makes it harder to get into the fuel filter. Change your fuel filter and add in a diesel additive and see how you get on.

dak

bear1 wrote: »

Possibily a failing fuel filter. With the colder weather diesel can get a bit more gelly like which makes it harder to get into the fuel filter. Change your fuel filter and add in a diesel additive and see how you get on.

Thats just what the garage did a week ago . Diptane in tank . Its improved , have only used half tank since in garage but still erratic if engine stone cold. Hoping it will improve when Diptane gone through system completely.
Dak

dak

Caliden wrote: »

No it was a bmw 120d. Idled very rough and a good bit of smoke on cold mornings.

I dont get any excess smoke of any colour!