running 172 when cold

[pete_pete]

when cold my 172 runs a bit nasty only when slowly reving from 1-2500 revs it splutters and theres a slight vibration sound now and again but is fine when warm. is this normal or should I be taking it in to be looked at. it has 12thou of mostly m-way miles.

 

[Viv172]

A lot of people say this is normal for their 172 so nothing to worry about.

 

[172 Horses]

I have a week & a half old 172. I have the same symptoms when starting from cold.

 

[Viv172]

Theres been quite a few postings about this, try doing a search.

 

[pete_pete]

thanks I will however If its something they do then Im ok with it

 

[Leah172mk2]

I have nearly 6k on mine and its started developing the same symptoms as yours but i think its just another renault trait. So nothing to worry about, hopefully

 

[Flying Scotsman]

Try this wee experiment. Start up the car from cold, remain stationtionary, out of gear and hold it at about 2K revs and watch what happens when the temperature guage gets up to the 1st notch from the bottom. It suddenly "clears its throat" and suddenly revs higher and cleaner. This is thought to be a current emissions ruling where it allows the CAT to heat up for about about 5 mins on lean run.

 

[Leah172mk2]

Cheers Flying Scotsman. Will give that a try tomorrow morning and ill see what happens

 

[Smith172]

From my experience lower octane fuels give you a lumpy start-up, try Shell Optimax or super unleaded, this should smooth things out, it wont completely get rid of the problem but it definitely improves the overall running of the car.

 

[GR7]

Try turning off the air con for while, as this uses up power and loads of extra fuel too. It is best not to, but if you turn the temp down, it has to work very much harder and also uses up loads more fuel.

 

[BenR]

The aircon is a smart unit that will automatically disengage itself during startup, then engage again a few secs later....but turning it off helps, nice one GR!

And the rough cold idle IS, no buts, maybes or IFs, due to EURO3 emmisions compliance. Fact is your catalytic coverter uses heat to change the composition of the waste gasses, when u start it from cold, the cat doesnt work, it doesnt do anything for emmisions. And EURO 3 law is exactly the same emmisions levels as EURO 2 but WITHOUT the 5 minute warmup period. This is why the engine has to run lean (to meet the emmisions from the off) and rough for till its warmed the cat up to do its job. This is also why the MK2 has a single cat and not a twin item like the MK1 as it warms faster, its also why they have the second lambda.

Fuel, pluh or anything else wont help solve it........just use full throttle when you leave your rd, only up to about 3500rpm, itll warm up faster and before anybody says it, its not bad for the engine no.

 

[Smith172]

Fuel, pluh or anything else wont help solve it........just use full throttle when you leave your rd, only up to about 3500rpm, itll warm up faster and before anybody says it, its not bad for the engine no.

As I said using Otimax or super unleaded doesnt completely cure the problem but it certainly improves the cars cold starts, Ive asked several other 172 owners about this and they are all in agreement that well the car is still lumpy when cold its definetely less so with the higher octane fuels.

 

[BenR]

i know it always looks like im argueing..............well, i guess i am.

But i cant see a reason y. My 172 was fine after a 30 sec blat.......it warms up damn fast that engine! lol

 

[JillyB]

My car hates being driven when its cold, its like you say, it takes mile or so to clear its throat

 

[McBunny]

my car couldnt give a toss seems fine when cold lol or is it that i just dont care

 

[greeper]

I had this on my old 172, I changed the oil using a better quality one and it was smooth running from cold and started first time everytime.

 

[visceral]

I always warm mine up for 30 mins in the garage with the door shut......car runs great but I keep getting these terrible headaches.

I am joking BTW

 

[jpmad4it2]

greeper wat oil did u use? Im thinking of chagning mine soon.

 

[greeper]

you have mail jpmad4it2

 

[jpmad4it2]

thanks mate.

 

[Pete]

Its normal happens to most if not all of the 172 Mk2s not sute about the mk 1s.

 

[pete_pete]

well I use super plus Texaco not optimax as I think its overated and I had it serviced last week I wonder if reno use cheap oils for there services or weather they put in nice (expensive) stuff for the bigger engines ie 172 or do they skimp, if so Im gonna chang it and put in some ting better..

 

[Flying Scotsman]

I use Mobil 1 and Optimax .......and still see the cold startup problems! TBH I see the course running problems more after the car as been sat from warm after 3-4 hours (normally lunchtime) more so than staring from dead cold in the mornings!

 

[BenR]

yea, we get a horrible about of hot start problems in HK with the 172, i would say posibly 20% of the 172s weve sold.

Our dealership runs Mobil 1 0w40 on all cars, most dealers just use the one big fat ol oil tank to supply everything.