Fast Idle / Engine as a generator / PTO Mod

[markopolo]

Edit: I found the PCM (Powertrain Control Module) in my GMC van and have updated this topic.

Engine as a generator............

What are Fast Idle and PTO?
http://www.gmupfitter.com/publicat/bull/bull64.pdf

Power Take Off (PTO) and Fast Idle both allow for elevated idle speeds to allow the engine to perform a desired task. In the past, engine speed increases were often a simple mechanical adjustment. With the advent of electronic engine controls, engine speed is now controlled by engine electronics. The Engine or Powertrain Control Module must now be used. Various combinations of wiring and programming changes may be required to implement these functions.

Fast Idle is sometimes called High Idle. It can be ordered on some vehicles as RPO UF3. It causes the engine to go to a single elevated speed for increased output from normal accessory drive components. Examples are increased voltage from the alternator or increased cooling from the HVAC compressor. Fast Idle can also take advantage of increased base engine heat output for fast vehicle heating.

PTO’s (Power Take Off’s) are used when hydraulic fluid is needed to do the work. It can be ordered on some vehicles as RPO PTO. The PTO unit itself typically mounts to the transmission or accessory drive. Notes: GM does not sell PTO’s as factory equipment; an up fitter must add them. Accessory Drive mounted PTO’s will invalidate the GM Accessory Drive Warranty. PTO differs from Fast Idle by offering a greater degree of control. These controls include multiple or variable engine speeds and increased turn on/off logic. PTO has more complex wiring for the Upfitter to install than Fast Idle. Some functionality comes standard from the factory in the PCM.

The mod discussed in this topic is more than a single speed fast idle. It can give you 3 additional idle speeds. It gives you PTO like idle speeds without having an actual PTO unit. Newer vehicles can have variable idle speeds. More on that later.

Why would you do it? It gives you:
Increased Air Conditioning for stationary operation.
Increased Electrical Output for stationary operation.
Increased Vehicle Heating for stationary operation.

My 1997 GMC Savana diesel idles at 624 RPM. I can run rear window type air conditioner off my inverter and the van dash air on "max air" blowing cold and the idle goes up to 651 RPM. Link: http://www.classbforum.com/phpBB2/vi...start=8#p12016
However, I've read that it is better for the engine to increase the idle to near 1,100 RPM if you want to idle it for extended periods.

Originally Posted by flashoffroad.com

Most manufacturers recommend around 1100 RPM for extended idle periods on diesel engines to prevent carbon deposits.

source: http://www.flashoffroad.com/Diesel/fast ... stIdle.htm

The fast idle mod on my van can give you up to 4 idle speeds:
Normal idle (624 RPM for my van)
1070 RPM
1360 RPM
1600 RPM

[markopolo]

The fast idle / PTO mod instructions for what I did can be found on Kennedy Diesel's website: http://www.kennedydiesel.com/FastIdleSetup.cfm The instructions shown are for a truck not a van. This applies to GM 6.5L diesel engines.

All electronic injected "drive by wire" 6.5s have provision for a fast idle for PTO or other use. This is particularly handy for warmup (heater) cool down (AC) as well as being easier on the engine if extended idle times are required.

OBD-II vehicle instructions are copied below. For ODB-I visit the Kennedy Diesel's website.

From: http://www.kennedydiesel.com/FastIdleSetup.cfm

'96 and up

Remove the glove box
Slide the PCM forward from its mounting behind the glove box. "I prefer to remove the PCM entirely"
Remove the center connector, by squeezing connector locks and pulling
Remove the lock on on top of the connector which corresponds to row B (Ais the top row & B is the bottom row, the bottom row is on the flat side)
Crimp one or two (depending on number of speeds desired) 18 ga. wire(s) to a terminal pin (p/n12089649) using a Packard Electric crimp tool (p/n 6285847) This tool is available from Pioneer-Standard Electronics @ 1-800-PACKARD
Insert the pin that will be connected to switch #1 with the attached 18-ga. wire in cavity B7 (the 7th hole from the right in the back, "wire side") Insert the pin that will be connected to switch #2 with the attached 18-ga. wire in cavity B8 ( the 8th hole from the right in the back "wire side") Make sure the terminal pins lock into the connector, now reinstall the connector in the PCM
Attach wire(s) to a switch (user furnished) connected to chassis ground

1070 RPM- ground pin B8
1360 RPM-ground pin B7
1600 RPM- short B7 and B8 together

The Fast idle will revert to base idle when the brake is pressed or if the selector is put into gear. Upon returning to park and releasing the brake, the fast idle will resume.
NOTE: Some trucks do not return to base idle uopn application of the brake. Be sure to verify this in a safe area.

Note: for OBD-II it is "Ground" the pins. Do not apply 12v to them!

Looks easy enough to do. You end up with a switch on the dash to turn on fast idle when you need it. 1070 RPM will be plenty. 1600 RPM would = 45 mph or so in my van!

[markopolo]

I had trouble finding the Powertrain Control Module (PCM) in my van. It ended up being up under the dash. Pretty much in the center but deep in there.
The PCM is item number 1 in the diagram below:



I started removing parts and then used my camera to zoom in and take some photos. I was then able to compare the photos I took to online images of the PCM module. It was comforting to know for sure that I had found it. This photo is zoomed and cropped. The PCM was very deep in there.



Two lower dash panels and the center console had to be removed. The engine cover had to be released and pulled back a bit to give me access to the PCM.

[markopolo]

I visited these sites for info re: the Re: Fast Idle / High Idle / PTO Power Take Off Mod. In no particular order:

http://www.kennedydiesel.com/FastIdleSetup.cfm

http://www.dieselplace.com/forum/showth ... p?t=230913

http://westersgarage.eidnet.ca/instructions.html

http://www.thetruckstop.us/forum/showth ... post220621

http://www.flashoffroad.com/Diesel/fast ... stIdle.htm

Wester's Garage has a PDF file with the 6.5L Turbo Diesel Fast Idle Upgrade Instructions for download. They also have PDF instructions for 2008 Fast Idle Upgrade for 6.0L Gas engines. It is for van builds with RPO code LY6.

More on RPO codes here: http://www.classbforum.com/phpBB2/vi...hp?f=17&t=1825

The 2008 gas engine instructions are much easier to do than on my 1997 diesel. It is all done with the cruise control - No tools needed!

2008 Fast Idle Upgrade for 6.0L Gas engines:
These conditions must be met for Fast Idle to work:
1. Park Brake must be set!!
2. Transmission/PRNDL must be in Park (P) or Neutral (N).
3. The Brake must not be pressed.
4. Vehicle Speed must be zero.

Enable Fast Idle by pressing and releasing the Cruise Control “ON” switch, the LED indicator on the switch will illuminate.
Preset Fast Idle by pressing and releasing the Cruise Control “SET” switch to achieve the preset 1200 RPM. This is not adjustable by a Tech2 scanner.
Variable Fast Idle is set by depressing and holding the accelerator at the desired RPM, then by pressing and releasing the Cruise “SET” switch to establish the desired Fast Idle speed.
The Variable Fast Idle speed can be observed on the tachometer. This ‘variable RPM value’ is not remembered at key off, so you’ll have to set it back where you want it with the above instructions.

Disable (turn off) Fast Idle.
Any of these conditions will cancel Fast Idle:
1. Turn Cruise Off. Press and Release the Cruise Control “ON/OFF” switch. The LED indicator should turn off.
2. Press and Release the Cruise Control “SET” switch
3. Press the brake pedal.
4. Press and Release the Cruise Control “CANCEL” switch.
5. Release the Park Brake.
6. Move the Transmission Shift Lever (PRNDL) from Park (P) or Neutral (N).

Download the PDF instructions at http://westersgarage.eidnet.ca/instructions.html

[markopolo]

I ended up using a single pole, double throw switch. Up is 1070 RPM idle, center is off 624 RPM normal idle, down is 1360 RPM idle. I did not enable 1600 RPM idle. I could do it later as it uses the same two wires but I doubt I'd use it.