![]() |
|
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. |
|
![]() ![]() |
![]() |
brooks944 |
![]()
Post
#1
|
Member ![]() ![]() Group: Members Posts: 249 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 |
MartyYeoman |
![]()
Post
#2
|
Senior Member ![]() ![]() ![]() Group: Members Posts: 1,531 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.
|
brooks944 |
![]()
Post
#3
|
Member ![]() ![]() Group: Members Posts: 249 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!
|
brooks944 |
![]()
Post
#4
|
Member ![]() ![]() Group: Members Posts: 249 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?
|
jim_hoyland |
![]()
Post
#5
|
Get that VIN ? ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 9,682 Joined: 1-May 03 From: Sunset Beach, CA Member No.: 643 Region Association: Southern 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. 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 |
MartyYeoman |
![]()
Post
#6
|
Senior Member ![]() ![]() ![]() Group: Members Posts: 1,531 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 |
brooks944 |
![]()
Post
#7
|
Member ![]() ![]() Group: Members Posts: 249 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?
|
malcolm2 |
![]()
Post
#8
|
Advanced Member ![]() ![]() ![]() ![]() Group: Members Posts: 2,747 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. |
brooks944 |
![]()
Post
#9
|
Member ![]() ![]() Group: Members Posts: 249 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.
|
brooks944 |
![]()
Post
#10
|
Member ![]() ![]() Group: Members Posts: 249 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).
|
malcolm2 |
![]()
Post
#11
|
Advanced Member ![]() ![]() ![]() ![]() Group: Members Posts: 2,747 Joined: 31-May 11 From: Nashville Member No.: 13,139 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). 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. |
malcolm2 |
![]()
Post
#12
|
Advanced Member ![]() ![]() ![]() ![]() Group: Members Posts: 2,747 Joined: 31-May 11 From: Nashville Member No.: 13,139 Region Association: South East States ![]() ![]() |
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 |
white1975 |
![]()
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
|
brooks944 |
![]()
Post
#14
|
Member ![]() ![]() Group: Members Posts: 249 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! |
malcolm2 |
![]()
Post
#15
|
Advanced Member ![]() ![]() ![]() ![]() Group: Members Posts: 2,747 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. |
brooks944 |
![]()
Post
#16
|
Member ![]() ![]() Group: Members Posts: 249 Joined: 5-September 10 From: Kingston, TN Member No.: 12,139 Region Association: South East States ![]() |
|
Root_Werks |
![]()
Post
#17
|
Village Idiot ![]() ![]() ![]() ![]() ![]() Group: Members Posts: 8,653 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.
|
brooks944 |
![]()
Post
#18
|
Member ![]() ![]() Group: Members Posts: 249 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!
|
malcolm2 |
![]()
Post
#19
|
Advanced Member ![]() ![]() ![]() ![]() Group: Members Posts: 2,747 Joined: 31-May 11 From: Nashville Member No.: 13,139 Region Association: South East States ![]() ![]() |
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? |
timothy_nd28 |
![]()
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. |
![]() ![]() |
![]() |
Lo-Fi Version | Time is now: 25th April 2025 - 12:36 AM |
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 ... |