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 )

2 Pages V  1 2 >  
 Reply to this topicStart new topic
> 75 still running rich, 75 still running rich
brooks944
post Jun 26 2017, 02:19 PM
Post #1


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
My 75 is running rich and fouling plugs after just a few miles. One of the members spent several hours helping me check and figure out the FI a couple of years ago and that made a difference (both on the car and how much I value your experts here). I have 2 extra 'brains' is it time to change that and check? One is from a '75 and one from a 74, does that matter? Both are for a 1.8 which my car is. Fuel injectors are rebuilt as well as the cold start valve. Most vacuum hoses changed. Thanks for any input.

Rick
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
MartyYeoman
post Jun 26 2017, 02:25 PM
Post #2


Senior Member
***

Group: Members
Posts: 1,517
Joined: 19-June 03
From: San Ramon, CA
Member No.: 839
Region Association: Northern California
Check the pin count on the ECU. Some have six and some have seven. I believe a '75 1.8 L-Jet ECU has seven.
User is online!Profile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 26 2017, 02:32 PM
Post #3


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
Not sure what that you mean, thanks for replying!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 26 2017, 02:38 PM
Post #4


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
Probably a dumb reply, but do you have pics of what I should be looking for?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
jim_hoyland
post Jun 26 2017, 02:40 PM
Post #5


Get that VIN ?
*****

Group: Members
Posts: 9,261
Joined: 1-May 03
From: Sunset Beach, CA
Member No.: 643
Region Association: Southern California
QUOTE(Marty Yeoman @ Jun 26 2017, 01:25 PM) *

Check the pin count on the ECU. Some have six and some have seven. I believe a '75 1.8 L-Jet ECU has seven.


He may be referring to the connector at the AFM; some are 6 pin, others 7. The AFM has to be compatible with the ECU. Don' have the part numbers handy, but they have been posted several times
User is online!Profile CardPM
Go to the top of the page
+Quote Post
MartyYeoman
post Jun 26 2017, 02:46 PM
Post #6


Senior Member
***

Group: Members
Posts: 1,517
Joined: 19-June 03
From: San Ramon, CA
Member No.: 839
Region Association: Northern California
Sorry My Bad. I meant AFM not ECU

Check this out for a good read. Not exactly 914 subject matter but close enough.

http://www.firstfives.org/faq/ljet/jetronic.pdf
User is online!Profile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 26 2017, 05:09 PM
Post #7


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
Thanks, is the probable issue the AFM instead of the brain?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
malcolm2
post Jun 26 2017, 05:56 PM
Post #8


Advanced Member
****

Group: Members
Posts: 2,738
Joined: 31-May 11
From: Nashville
Member No.: 13,139
Region Association: South East States
So, did this just happen? Did something change, or has it been doing this for a long time?

You said the Injectors were rebuilt. When? Did you put them right in? They can gum up with the rebuilding fluid if you let them sit a while. I had to send mine back so they could clean them just before I was ready to crank.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 27 2017, 08:31 AM
Post #9


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
The injectors were rebuilt a couple of years ago and installed into the car when they came back.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 27 2017, 08:38 AM
Post #10


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
Also, the 75 has seven pins (I also have a 74 and the connection to the man on that car has 6).
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
malcolm2
post Jun 27 2017, 10:47 AM
Post #11


Advanced Member
****

Group: Members
Posts: 2,738
Joined: 31-May 11
From: Nashville
Member No.: 13,139
Region Association: South East States
QUOTE(brooks944 @ Jun 27 2017, 09:38 AM) *

Also, the 75 has seven pins (I also have a 74 and the connection to the man on that car has 6).


So you can't use a 74 6-pin AFM on the 75 7-pin harness.

If either AFM ever becomes totally unobtainable, I am sure with some studying of where the pins go etc...they could be made to work properly. Until then, if you want one for your car, buy a 7-pin one.

If the flap moves freely and no one has messed with the spring or gear then it is probably not bad. Sometimes you can tell just by trying to remove the plastic lid. If it is tuff to get off and the seal looks good, it my be a virgin.

They can be tested. Can't remember if I did, but I do remember checking into bench testing.

The bent flap is a dead give-away. But that causes a no-run, no-idle, no-start problem, not a rich issue.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
malcolm2
post Jun 27 2017, 10:54 AM
Post #12


Advanced Member
****

Group: Members
Posts: 2,738
Joined: 31-May 11
From: Nashville
Member No.: 13,139
Region Association: South East States
QUOTE(brooks944 @ Jun 27 2017, 09:31 AM) *

The injectors were rebuilt a couple of years ago and installed into the car when they came back.


You still might want to test them, Cold Start valve too. Checking the squirt pattern, volume and to see if they leak. Poor pattern or leaking would sure cause a rich issue.

I'll see if I can find a post when Tim helped me do that. IIRC we jumped some wires turned the key and I operated the AFM flap while the injectors sprayed into jars. Again, IIRC you do 1 side at a time. You can compare the output, pattern and leaking with one 5 second squirt.

BTW is your 75 a true 1.8 (1756cc) or has it been upgraded to a 1911?

Clark
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
white1975
post Jun 27 2017, 11:02 AM
Post #13


Member
**

Group: Members
Posts: 94
Joined: 28-December 10
From: Milford ohio
Member No.: 12,529
Region Association: None
cht sensor is bad I would say if the afm is not stuck
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 27 2017, 12:20 PM
Post #14


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
Tim did help me check out the maf, it worked fine. My car has been modified to 1911cc. It sounds to me more and more like the chat sensor. These don't seem to be that expensive, are they hard to replace?

Thanks everyone for the help!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
malcolm2
post Jun 27 2017, 12:57 PM
Post #15


Advanced Member
****

Group: Members
Posts: 2,738
Joined: 31-May 11
From: Nashville
Member No.: 13,139
Region Association: South East States
Here is a simple test for you to try....

study up on Jeff's ECU wiring layout. HERE... http://bowlsby.net/914/WiringHarnesses/Har...FI_EC75-1.8.pdf

Disconnect your ECU connector. Set your Volt meter on OHMS and put one lead on the pin of the connector labeled 13 in the link above. That wire goes to the CHT.

Put the other one on metal somewhere on the car (bare metal, not paint), or the negative post on the battery.

Tell us the result on the meter.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 27 2017, 02:26 PM
Post #16


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
Here are some pictures of the spark plugs, probably less than 50 miles. Thanks everyone for your help.Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Root_Werks
post Jun 27 2017, 03:15 PM
Post #17


Village Idiot
*****

Group: Members
Posts: 8,305
Joined: 25-May 04
From: About 5NM from Canada
Member No.: 2,105
Region Association: Pacific Northwest
As some have stated, could be CHT, my money is on a vaccuum leak. Buy a tester and start checking each part.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
brooks944
post Jun 27 2017, 03:45 PM
Post #18


Member
**

Group: Members
Posts: 241
Joined: 5-September 10
From: Kingston, TN
Member No.: 12,139
Region Association: South East States
Thanks, what do I need for a vacuum leak. Changed too many hoses and did the cigar test!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
malcolm2
post Jun 27 2017, 03:55 PM
Post #19


Advanced Member
****

Group: Members
Posts: 2,738
Joined: 31-May 11
From: Nashville
Member No.: 13,139
Region Association: South East States
QUOTE(brooks944 @ Jun 27 2017, 04:45 PM) *

Thanks, what do I need for a vacuum leak. Changed too many hoses and did the cigar test!


I made me a smoke tester. Couple pieces of charcoal in a fresh paint can from HD. Compressed air in, smoke out. attach to a vac line on the car and see where the smoke comes out. I will find my post and link it here.

http://www.914world.com/bbs2/index.php?s=&...t&p=2450938

Did you check your CHT: ECU 13 to ground yet?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
timothy_nd28
post Jun 27 2017, 05:51 PM
Post #20


Advanced Member
****

Group: Members
Posts: 2,299
Joined: 25-September 07
From: IN
Member No.: 8,154
Region Association: Upper MidWest
Hi Rick, I've been following this thread but too busy to put much thought into your issues. I'm preparing for the MCAT exam this week which has been nonstop studying.
Clark (Malcom2) will help walk you through, especially if you have any vacuum leaks.
Heed his advice and don't replace any parts until you have thoroughly tested them.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

2 Pages V  1 2 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

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

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

- Lo-Fi Version Time is now: 25th April 2024 - 10:23 AM
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 ...