EFI computer learning curve?

[Chips67]

When i start up my 5.0 efi for the first time do i just let it idle for a long time or do you go up and down with rpm's? whats best for the computer to learn.and also, i had a speed density computer out of a manual trans car, now i have a mass air out of an auto car, do i need to change out o2 sensors to the auto trans or will the manual ones work?

[highlander]

The computer should learn best under normal driving conditions. Idling or varying the RPM shouldn't effect the learning curve. The computer doesn't need much time to get things running right, what the computer learns over time only smooths things out. If it is a new or rebuilt engine letting it idol for a any significant time is the worst thing you can do. There is no difference between auto and manual O2 sensors.

[SonicDonkey]

Since were taliking EFI... Mine seems to hunt for idle pretty bad as cold start, always has. If I pull on my hand throttle a little bit to raise the RPM's to 1200 or so then it will warm up fine but if I dont it will end up dieing due to the high low hunt.

Any thoughts?

[Chips67]

Thanks for the advise, hey Sonic, from what i understand the idle air valve mounted on the side of the throttle body helps with cold start idle control till engine warms up, that could be bad or not functioning properly.

[Lars]

Since were taliking EFI... Mine seems to hunt for idle pretty bad as cold start, always has. If I pull on my hand throttle a little bit to raise the RPM's to 1200 or so then it will warm up fine but if I dont it will end up dieing due to the high low hunt.

Any thoughts?

Check the basics first. No vacuum leaks anywhere?

Maybe you know this already, but is the crankcase vented to the outside world or to the throttle body? If you vent to the atmosphere then air is being sucked into the intake via the crankcase & PCV that the computer can't account for, especially when it's cold and running in open loop. Factory setup is a hose from the nipple on the side of the oil fill tube on the passenger valve cover, to the nipple on top of the throttle body.

Assuming all that is in order, wait till the engine is stone cold. Unplug the connector on the ISC (also known as IAB) valve on the side of the throttle body and disconnect the Spout connector. Start the engine. Does it try to idle at the same rpm as before or lower? Does it surge? While the engine is running, reconnect the Spout, then the ISC. If it starts to surge when you reconnect the Spout and doesn't go away when you reconnect the ISC, then the ISC may be clogged with soot and crud. You can usually revive them by hosing them down with carb cleaner.

[SonicDonkey]

Check the basics first. No vacuum leaks anywhere?

Maybe you know this already, but is the crankcase vented to the outside world or to the throttle body? If you vent to the atmosphere then air is being sucked into the intake via the crankcase & PCV that the computer can't account for, especially when it's cold and running in open loop. Factory setup is a hose from the nipple on the side of the oil fill tube on the passenger valve cover, to the nipple on top of the throttle body.

Assuming all that is in order, wait till the engine is stone cold. Unplug the connector on the ISC (also known as IAB) valve on the side of the throttle body and disconnect the Spout connector. Start the engine. Does it try to idle at the same rpm as before or lower? Does it surge? While the engine is running, reconnect the Spout, then the ISC. If it starts to surge when you reconnect the Spout and doesn't go away when you reconnect the ISC, then the ISC may be clogged with soot and crud. You can usually revive them by hosing them down with carb cleaner.

Thanks Lars, I will keep this handy for when the fuel tank is back in!