Webinar #217

On the idle airflow section . Does it matter at what rpm your engine idles at during the warm up stage . To correctly fill in the histogram ?? Personal preference I have a fast idle of 1,600rpm when the engine first starts in the morning. Tappers off with coolant temp . While in P/N . Gen 3. G.M. Cable throttle. Live in the U.S. morning temps can be -15F -26C during winter . Terry

Part of it may depend on the fuel you have to use, and it's alcohol content, as ethanol can be problematic at low temperatures as it doesn't evaporate/mix with the fuel and ignite as readily as straight petrol/gasoline - you may find OEM spark plug gaps, or larger, work much better than closer ones often required for higher boost.

As a general rule, fast enough and with enough fuelling to maintain a reliable idle.

OEM settings are usually much faster and with more fuelling than required, because their focus is on avoiding any possible cold idle/running issues under any conditions.

You don't say if you're using a manual or auto', if the latter you may find you need to drop the idle speed more.

You also don't mention if you start the engine and leave it idling before driving, or start it and drive? With the first it may be better to run a higher idle with the minimum of fuelling, to reduce bore wash - especially with fuels containing alcohol - and oil dilution. If the latter, possibly the other way round to improve driveability - still aiming a little on the lean side, if possible.

From the way the process is presented in the webinar to fill in the table was to start the vehicle stone cold and let it idle until the engine was fully warmed up . OE table cold start rpm is 825rpm 625rpm warmed up . Just that my table I have cold start at 1,600rpm . 625rpm warmed up . So I am wondering if I need to set the table back to OE rpm values ?? Or It does not matter if my cold start is at a higher rpm . So you can’t drive it . Transmission it would not matter. Because your trying to fill in the Idle air flow table . While sitting stationary and idling.

Hello i don't think the idle speed will matter to much at all, you have to have it at the rpm your engine needs to give the best idle and fastest warm-up possible