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https://oldsite.omegaowners.com/forum/YaBB.pl Omega Help >> Omega General Help >> Better when cool https://oldsite.omegaowners.com/forum/YaBB.pl?num=1156361989 Message started by JasonH on 23. Aug 2006 at 20:39

Title: Better when cool
Post by JasonH on 23. Aug 2006 at 20:39

I've noticed that on cooler days my car runs smoother.

When the ambient air temperature is high the car definitely has a lumpier tickover and just doesn't rev as smoothly. It's not to do with engine temperature either because the effect is fairly immediate. Hot day, cold start = lumpy, then stays lumpy.

I'm thinking air intake temperature sensor and/or MAF.

No error codes and car otherwise fine.

Thoughts anyone. What about cleaning the sensors?

Title: Re: Better when cool
Post by Tezray on 23. Aug 2006 at 20:48

Are you sure it's not just to do with air humidity/density? Because these factors do have a definite impact on performance and unfortunately there's not a lot you can do about it....Is it really very noticeable? I notice it in mine, but i am very picky/sensitive to things like that lol

Title: Re: Better when cool
Post by JasonH on 23. Aug 2006 at 21:40

I'm really picky too! I suspect someone else wouldn't notice the difference - but I do!

Title: Re: Better when cool
Post by tunnie on 23. Aug 2006 at 22:16

my car runs much better on a cooler day, most cars do.

Title: Re: Better when cool
Post by markjay on 23. Aug 2006 at 22:17

...what grade oil do you use? 10w40?

Title: Re: Better when cool
Post by JasonH on 24. Aug 2006 at 08:48

Vx 5W30 full synth, long life.

Oh no an oil thread....

Title: Re: Better when cool
Post by Marks DTM Calib on 24. Aug 2006 at 08:56

Well they are bound to run better on a cold day.

Have a read of the MAF sensor FAQ and consider that when its cold, the air mass is higher and hence you can get more air into the engine.

Title: Re: Better when cool
Post by mjl1644 on 24. Aug 2006 at 13:37

...perhaps this is why they invented Intercoolers.... :-/

mike

Title: Re: Better when cool
Post by markjay on 24. Aug 2006 at 14:05

I am a bit confused about the fact that the difference is when idling - I think the air volume should have more of an impact at high engine revs.

Going back to the oil issue... (I know, I know ;D)

The 5W-30 is a new full-synth oil from Vx (replacing the older 5W-40), so I am assuming that you only recently started using it - can you tell if this rough idling on hot days issue was there from the start, or did it appear after you first changed the oil to 5w-30?

Title: Re: Better when cool
Post by JasonH on 24. Aug 2006 at 14:47

It was there with 5W40 too.

TBH it's not that bad, but it's noticeable.

Title: Re: Better when cool
Post by zoltron on 24. Aug 2006 at 22:33

I'm a complete fool when it comes to how engines work but as I always understood it the colder the air entering the engine the more it aids combustion, is this the basic principal of performance cars?