[Subscribe to Daily Digest] |
 | [Main General Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
The old 'blow it out' tale Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 27 Jul 2007 18:12:44
In Reply to: Emission Test Myth, Fact or Fiction, DAnH  [Profile/Gallery]
, Fri, 27 Jul 2007 13:21:52
Members do not see ads below this line. - Help Keep This Site Online - Signup
|
My father-in-law used to talk about that - take the car out on the highway and 'blow it out' with some high speed runs. Of course, you can run an engine at speed just as well in a low gear at 25 MPH as you can at 80 in top gear. Yes, the engine is more heavily loaded.
With a modern car, you want the engine warm - operating temperature. With heaters, O2 sensors are on-line within about 3 minutes. Cats are designed for fast light-off to reduce emissions when cold. Unless your thermostat is stuck open and the car is taking forever to reach normal temperature, just normal driving for about 10 minutes will get the car up to normal operating temp.
I don't see any advantage in getting the car really warm. And you don't, really - that's what the cooling system is for. The most you'll be able to do is get the block a few degrees warmer for a while. And frankly, the hottest and engine runs is when it's idling with only fan air over the radiator - so you'll get it hotter waiting in line for the test than on the drive over.
In terms of engine temp, NOx are driven by hot running. But not in terms of coolant temps, but in terms of combustion temperatures. That's more a factor of ignition timing, compression, hot spots, and mostly, mixture.
What you SHOULDN'T do is rev the engine prior to the test. No big throttle blips. Acceleration puts the engine into open loop operation, running rich. It'll take a bit of time for the extra HC to work its way through the system. Just for fun on an older car, we tried blipping the throttle. It took almost 45 seconds for the HC to drop back down to idle levels.
What's the key to passing the test - make sure the car is tuned up properly. Track down and kill all vacuum leaks. Make sure the plugs are fresh and properly gapped, and the right kind. Clean air filter.
posted by 75.25.4...
, Fri, 27 Jul 2007 13:21:52, Fri, 27 Jul 2007 18:12:44 <-- Viewing This Message, Fri, 27 Jul 2007 16:32:49
, Fri, 27 Jul 2007 15:40:49, Fri, 27 Jul 2007 16:05:29
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
