good responce from start

[sharki786]

Has anyone noticed a good responce from ther car wen its jus been started? & when the temp gets halfway does ur car get slugish?

[DazVR6]

Ive heard of this but tbh its not good for your car, keep it under 2000 revs till your oil temp get to atleast 80 degrees.

I read somewhere that some people feel that their cars perform bettr some days and are slugish on others but no one really knows why.

Do you have and induction kit by the way..?

[sharki786]

no its jus a standard box with standard filter but got a direct air intake from under the fod lite. ooops  :embarassed: i did that yday beter not now.

[DazVR6]

no its jus a standard box with standard filter but got a direct air intake from under the fod lite. ooops  :embarassed: i did that yday beter not now.

Ah ok coz i was gonna suggest that maybe your sluggishneess was caused by heatsoak.....is yours a 16v..?

[Khare]

When its your engine is cold the fuel pressure is higher, so therefore car does feel more responsive. You can get fuel pressure regulators to keep a constant high pressure but without other mods its useless...
And cars are more responsive on colder days than warmer days.
I love driving on a night with the cold dense fog, car runs sweet as a nut.
Cold air = more oxygen
more oxygen = better combustion
better combustion = more power.

[danny_p]

When its your engine is cold the fuel pressure is higher, so therefore car does feel more responsive. You can get fuel pressure regulators to keep a constant high pressure but without other mods its useless...

wtf  are you on about.

proably a lot more likely to be sendor related. or mucky injectors.    all my enignes have allways been keenest when hot  when setup and in good heath

[Agreeable Slick]

When its your engine is cold the fuel pressure is higher, so therefore car does feel more responsive. You can get fuel pressure regulators to keep a constant high pressure but without other mods its useless...
And cars are more responsive on colder days than warmer days.
I love driving on a night with the cold dense fog, car runs sweet as a nut.
Cold air = more oxygen
more oxygen = better combustion
better combustion = more power.

As pointed out above, generally wrong, but also:

Cold air = DENSER air, not more oxygen. It just means that the air to fuel ratio goes up ever so slightly, giving a denser combustion area.

Overall it means that the combustion is closer to a stoichiometric value. Still not perfect.

[Khare]

When its your engine is cold the fuel pressure is higher, so therefore car does feel more responsive. You can get fuel pressure regulators to keep a constant high pressure but without other mods its useless...

wtf  are you on about.

proably a lot more likely to be sendor related. or mucky injectors.    all my enignes have allways been keenest when hot  when setup and in good heath

then why do people do the WUR mod on the mk2?

Cold air = DENSER air, not more oxygen. It just means that the air to fuel ratio goes up ever so slightly, giving a denser combustion area.

and denser air contains more oxygen becuase molecules are packed together.

[rubjonny]

On a digi injection car the fuel pressure is always the same, this is maintained by the FPR and temperature does not effect it.

On a k-jet car again the fuel pressure inside the main body of the metering head is always the same, around 5 bar. This is maintained by a pressure relief valve inside the metering head, and is not effected by temperature.
For cold running the WUR actually reduces the fuel pressure to the chamber above the fuel metering pin, allowing it to travel higher for any given air meter flap movement, increasing the fuel volume.  This pressure is gradually increased as the car warms up.
Also the WUR mod reduces the fuel pressure to the pin (warm control pressure), from the factory value of 49-55PSI, to around 48PSI, allowing the pin to move higher, increasing the volume delivered.

[Khare]

ahh right. that makes sense now!  :embarassed: