86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

CMH - keep it or block it?

Old 01-11-2019, 02:54 AM
Registered User
Thread Starter
karlm-c's Avatar
Join Date: Feb 2016
Location: Quiet Corner, CT
Posts: 58
Likes: 0
Received 0 Likes on 0 Posts
CMH - keep it or block it?

Hello everyone,

Long time since I've been on here, but I need some advice. I just had my 22R out of my '86 truck, did a full gasket job, HD timing replacement, waterpump, oil pump, painted everything, did all sorts of stuff. I did an EGR delete a while ago when I installed my 32/36 with manual choke, but never thought it was worth doing the intake water block kit. I thought the wire from the bottom of the intake was a sensor, something for the electric choke.

Now I realize the CMH is actually a heater, used for cold starts.

I can't find any good information about this thing. What I would like to do, is to bypass the truck control of this unit and add a spring switch to the dashboard. Like in my diesel construction equipment with the engine heater, when you're starting, hold the switch, let go and it turns off.

Is this worth it? I installed a freeze plug block heater, so I doubt its really necessary, but going above and beyond is kind of my thing, and I like the idea of this heater so i don't want to buy the LCE block plate and get rid of it if I can make it work in my favor.

Let me know if anyone has any experience with this, or if I just block it off, remove the fuse and trace back and delete the wires.


karlm-c is offline  
Old 01-11-2019, 08:58 AM
Registered User
old87yota's Avatar
Join Date: Jun 2013
Location: Portland, Oregon, USA
Posts: 2,044
Received 127 Likes on 117 Posts
Here is how the Cold Mixture Heater works:

The factory system uses coolant temperature input and a charging input (meaning the engine is running) to help determine when the emissions computer should turn the heater on.

Basically when you swap to a Weber 32/36, all of the factory methodology goes out the window and many driveability / emissions systems get "deleted" as they are not compatible with the minimalist approach of the Weber.

I don't think it would be worth it to wire a switch to the dash as you would be guessing when to turn it on and when to turn it off, with probably little benefit with the Weber and block heater.

If you are still unsure, you can leave it as is, unplugged, and experiment to see if it makes a difference with your setup. You can also just leave the heater in place and just not use it.

old87yota is online now  
Related Topics
Thread Starter
Last Post
Buying & Selling Advice - Feeler/Gauging Interest
01-16-2011 07:40 AM
Newbie Tech Section
01-02-2011 06:58 AM
86-95 Trucks & 4Runners
08-11-2008 11:15 PM
95.5-2004 Tacomas & 96-2002 4Runners
11-18-2005 02:32 PM

Thread Tools
Search this Thread
Quick Reply: CMH - keep it or block it?

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: