Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
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.
 

Welcome Guest ( Log In | Register )

> Cylinder Head Temperature Sensor, Electrical Characteristics ??
mnementh
post Aug 16 2006, 06:50 PM
Post #1


Newbie
*

Group: Members
Posts: 16
Joined: 10-September 04
From: Lebanon, OH
Member No.: 2,735
Hello All,
I hope someone can help me out a little bit. Does any one know the electrical characteristics of the cylinder head temperature sensor ? As in what is the resistance range over a given temperature range ? I know the resistance goes down as the temperature goes up. Also, as the temperature increases, does this sensor enrich or derich the fuel mixture ? I am looking to bias my sensor a little to try and correct a wicked rich condition. Thanks for any info you may have.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
 
 Reply to this topicStart new topic
Replies(1 - 10)
jhadler
post Aug 16 2006, 06:58 PM
Post #2


Long term tinkerer...
***

Group: Members
Posts: 1,879
Joined: 7-April 03
From: Lyons, CO
Member No.: 529
I don't remember the resistance values off the top of my head...

The resistance drops as it heats up (thermistor). It's designed for enrichment when themotor is cold. So as the engine heats up, and the resistance drops, the ECU leans out the mixture. A common "patch" is to place a 270 ohm resistor in-line with the HTS to richen the mixture up a little.

-Josh2
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mueller
post Aug 16 2006, 06:58 PM
Post #3


914 Freak!
***************

Group: Members
Posts: 17,150
Joined: 4-January 03
From: Antioch, CA
Member No.: 87
Region Association: None
here you go....

L-Jet troubleshooting and info
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mnementh
post Aug 17 2006, 02:27 PM
Post #4


Newbie
*

Group: Members
Posts: 16
Joined: 10-September 04
From: Lebanon, OH
Member No.: 2,735
Josh and Mueller,
Outstanding, Thanks for the help. Using the web location, I was able to build a profile for the sensor, then model different resistances both in series (enriches mixture) as well as parallel (leans out mixture). Sorry, Electrical Engineer peeking out again (IMG:style_emoticons/default/yellowsleep[1].gif) 270 ohms is some serious enrichment. Again, thanks for the help, and I will post the results of some testing I will do on playing with the resistances.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ptravnic
post Aug 17 2006, 02:30 PM
Post #5


Senior Member
***

Group: Members
Posts: 1,231
Joined: 27-May 03
From: Chicago, IL
Member No.: 747
Region Association: None
Check w/ Drewvw He's done some resistor modification along the lines that you are talking about.

-pt
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Cap'n Krusty
post Aug 17 2006, 03:32 PM
Post #6


Cap'n Krusty
**********

Group: Members
Posts: 10,794
Joined: 24-June 04
From: Santa Maria, CA
Member No.: 2,246
Region Association: Central California
QUOTE(mnementh @ Aug 16 2006, 05:50 PM) *

Hello All,
I hope someone can help me out a little bit. Does any one know the electrical characteristics of the cylinder head temperature sensor ? As in what is the resistance range over a given temperature range ? I know the resistance goes down as the temperature goes up. Also, as the temperature increases, does this sensor enrich or derich the fuel mixture ? I am looking to bias my sensor a little to try and correct a wicked rich condition. Thanks for any info you may have.


If you have a "wicked rich condition" on an AFC car, it's almost always a bad airbox. The CHT isn't gonna be involved once the engine is fully warmed up. You might also check the fuel pressure and the operating voltage, but my money's on the airbox.

The Cap'n
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ptravnic
post Aug 17 2006, 08:28 PM
Post #7


Senior Member
***

Group: Members
Posts: 1,231
Joined: 27-May 03
From: Chicago, IL
Member No.: 747
Region Association: None
[quote name='Cap'n Krusty' date='Aug 17 2006, 05:32 PM' post='754493']
[quote name='mnementh' post='753786' date='Aug 16 2006, 05:50 PM']

If you have a "wicked rich condition" on an AFC car, it's almost always a bad airbox.
[/quote]


A bad airbox, like not sealing correctly?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mnementh
post Aug 18 2006, 06:45 PM
Post #8


Newbie
*

Group: Members
Posts: 16
Joined: 10-September 04
From: Lebanon, OH
Member No.: 2,735
OK. All good info, because I am currently on a steep learning curve. I will check out the air box and see what is going on there. Thanks a lot for the help.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Cap'n Krusty
post Aug 18 2006, 07:40 PM
Post #9


Cap'n Krusty
**********

Group: Members
Posts: 10,794
Joined: 24-June 04
From: Santa Maria, CA
Member No.: 2,246
Region Association: Central California
[quote name='ptravnic' date='Aug 17 2006, 07:28 PM' post='754715']
[quote name='Cap'n Krusty' date='Aug 17 2006, 05:32 PM' post='754493']
[quote name='mnementh' post='753786' date='Aug 16 2006, 05:50 PM']

If you have a "wicked rich condition" on an AFC car, it's almost always a bad airbox.
[/quote]


A bad airbox, like not sealing correctly?
[/quote]

Like, "broken", either electronically or physically. L-jet 1.8s have an airbox, more properly called an "airflow meter", and they go bad, generally resulting in a exceedingly rich condition. They're car specific, meaning the '74 takes one, the 75 another, and they fit no other car (well, except the 74 T4, but where are you ever gonna find parts for one of those?). The reman units are a notorious waste of time and money, especially thiose from "Bret". Royze's aren't any good, either. New ones are basically NLA. Good luck, The Cap'n

BTW, reading through the other posts, it appears some folks think your car is D-jet, and consequently are telling you stuff that doesn't even apply to your car.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mnementh
post Aug 23 2006, 04:27 AM
Post #10


Newbie
*

Group: Members
Posts: 16
Joined: 10-September 04
From: Lebanon, OH
Member No.: 2,735
Cap'n,
I appreciate the input. I noticed that some of the info above was related to the D-Jet as well, but still appreciate the guys trying to help. I will use the troubleshooting guide on the link that Mueller provided and meter out the air box. I was looking inside it last night, and there appears to be a couple of grooves worn in the carbon track. Again, Thanks for the help.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bd1308
post Aug 23 2006, 07:31 AM
Post #11


Sir Post-a-lot
*****

Group: Members
Posts: 8,020
Joined: 24-January 05
From: Louisville,KY
Member No.: 3,501
L-jet was used on many other cars. Go junkyard shopping and retune one from another car.

does the vane move easily without sticking?

b
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

Reply to this topicStart new topic
3 User(s) are reading this topic (3 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Switch to: Standard · Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 26th December 2024 - 11:50 PM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...