Hey guys I just wanted to introduce myself seeing as I've been lurking in the shadows of this thread for over a year now. I finally joined the forum and just wanted to say thank you to you all for your sharing of the wealth of knowledge regarding everything 3RZ. Here is my swap into my 85 4runner:
The swap has been amazing with the exception of a few quirks that have come along with it. I am battling an issue where my truck will run great on a cold start, but upon restarting the engine when it is warm I will get a rough/low idle that goes away after driving for a few minutes. This is what a guy over on YT told me he thinks the issue is I'm wondering if you guys could add any input?
Two parts to this: 1. Heat Saturation and 2. Swapped parts/engines.
1. When under normal operation, the IAT (Intake Air Temperature) sensor normally sees air that's about 80-90 degrees on your normal sunny day. Usually 10-20 degrees higher than the ambient air temperature. When you shut off your engine and leave it for a little while, but not long enough for the engine to cool off, hot air from the combustion chamber "saturates" the air intake all the way to the IAT sensor. Now it's sensing some very hot air so it retards the timing when you go to start up your vehicle. Once driving again, the incoming air (80-90 degrees) cools off the IAT sensor and things return to normal.
2. When everything is bone stock, this is usually not an issue since the engineers compensate for this by programming the ECU to adjust for it, or there's extra airflow to cool it off. However, when you start swapping parts/engines from other vehicles it'll show up since it's not the manufacturer's original design.
Hope this helps. Short answer is: there's no way around but doesn't hurt anything.
Thanks guys
