I may be getting a 99 WJ Laredo (4.0 I6) at some point over the next year. Out of curiosity (and because I can't find any answer to this), is it possible to add a high idle (or "extended idle") switch to one of these, like on the 4.0 XJs? If so, how complicated would it be? If there is no simple way of doing it, is there a way to trick the TPS to raise the idle to about 1200rpm on command?
interested in this as well, i did it on my old cherokee and it was as easy as grounding a single wire with the switch. to my knowledge though, the WJ wasn't a popular government/police vehicle, so i don't know if it ever had that option.
i know there was a writeup somewhere about making the cruise-control switches work even in PARK to raise the idle as much as desired... not sure where that was though
The first link has pictures of the whole install the guy did on a EFI 4.0.
A EFI throttle body is similar to a carb but without the gasoline mixing aspect, linkage-venturi(s) and throttle plate(s) are still right on the "carb like" throttle body.
High idle raises the engine RPM at idle (in Park or Neutral) to 1200-1400 rpm (sometimes 1000). This improves alternator output when you are going to be idling for a few minutes, as well as allowing faster warm up on cold winter mornings. Also, it is bad for an engine (less oil to top end, fuel dilution of oil, etc) to run at a normal idle for more than a few minutes. At high idle, these problems are reduced or eliminated.
on the topic of improving alternator output, most alternators put out their peak amperage at typical driving RPMs, not idle. So, running high draw electronic accessories at idle can actually drain the battery.
This is why police and service vehicles typically have an extended idle option.
Installing HID's in stock housings is bad. Here is why.
"When you see someone who needs help, help them. When you see someone who needs a hug, hug them... Help those who can't help themselves."-Sgt Andrew Tingwall, NMSP. End of watch 6-10-2009