 D-Jet: CHT and the ECU, How the ECU reacts to the CHT resistance |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
| pbanders |
 Apr 10 2010, 02:13 PM
Post
#1
|
|
Senior Member  Group: Members Posts: 939 Joined: 11-June 03 From: Phoenix, AZ Member No.: 805  |
As you may know, the ECU uses the CHT resistance to determine how much to increase the injection pulse width (i.e. mixture enrichment) when the motor is cold. I have some charts on this on my ECU web page, and I simulated the action of the circuit, which showed that once resistance of the CHT dropped below about 300 ohms, the ECU no longer keeps leaning out the mixture - this is the "stead state" or "fully warmed up" mixture.
I never actually verified this behavior with an ECU, so I experiemented with three ECU's this morning (037, 043, and 052), and verified that what was simulated is how it actually acts. Independent of engine speed or load, once the CHT drops below about 330 to 375 ohms, the injection pulse width stays the same. |
   |
 
|
  |
Replies
| sean_v8_914 |
Apr 11 2010, 01:41 PM
Post
#2
|
|
Chingon 601 Group: Members Posts: 4,011 Joined: 1-February 05 From: San Diego Member No.: 3,541 |
funny/interesting that you would be observing this now. I have taken measurements in the course of troubleshooting that support your theory. the case and cylinders stay hot/warm long after teh heads have cooled. I have measured the change in resistance on teh CHT while teh oil remains hot. I look forward to reading your findings
|
|
|
|
Posts in this topic
pbanders D-Jet: CHT and the ECU Apr 10 2010, 02:13 PM
pbanders OK, to complete my comments on this - The next ste... Apr 10 2010, 03:34 PM
realred914
OK, to complete my comments on this - The next st... Apr 10 2010, 08:41 PM McMark Cool stuff! Thanks for sharing your experimen... Apr 10 2010, 08:04 PM Tom Thanks Brad for all of your research, you are doin... Apr 10 2010, 08:45 PM pbanders Re: realred914's comments - What I'm learn... Apr 11 2010, 01:32 PM 914_teener This is really interesting stuff. I am a real beli... Apr 11 2010, 04:27 PM |
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 12th June 2024 - 10:06 PM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.