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> 75 still running rich, 75 still running rich
brooks944
post Jun 26 2017, 02:19 PM
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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
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MartyYeoman
post Jun 26 2017, 02:25 PM
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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.
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brooks944
post Jun 26 2017, 02:32 PM
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Not sure what that you mean, thanks for replying!
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brooks944
post Jun 26 2017, 02:38 PM
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Probably a dumb reply, but do you have pics of what I should be looking for?
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jim_hoyland
post Jun 26 2017, 02:40 PM
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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
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MartyYeoman
post Jun 26 2017, 02:46 PM
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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
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brooks944
post Jun 26 2017, 05:09 PM
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Thanks, is the probable issue the AFM instead of the brain?
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malcolm2
post Jun 26 2017, 05:56 PM
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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.
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brooks944
post Jun 27 2017, 08:31 AM
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The injectors were rebuilt a couple of years ago and installed into the car when they came back.
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brooks944
post Jun 27 2017, 08:38 AM
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Also, the 75 has seven pins (I also have a 74 and the connection to the man on that car has 6).
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malcolm2
post Jun 27 2017, 10:47 AM
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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.
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malcolm2
post Jun 27 2017, 10:54 AM
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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
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white1975
post Jun 27 2017, 11:02 AM
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cht sensor is bad I would say if the afm is not stuck
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brooks944
post Jun 27 2017, 12:20 PM
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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!
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malcolm2
post Jun 27 2017, 12:57 PM
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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.
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brooks944
post Jun 27 2017, 02:26 PM
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Here are some pictures of the spark plugs, probably less than 50 miles. Thanks everyone for your help.Attached Image
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Root_Werks
post Jun 27 2017, 03:15 PM
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As some have stated, could be CHT, my money is on a vaccuum leak. Buy a tester and start checking each part.
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brooks944
post Jun 27 2017, 03:45 PM
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Thanks, what do I need for a vacuum leak. Changed too many hoses and did the cigar test!
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malcolm2
post Jun 27 2017, 03:55 PM
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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?
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timothy_nd28
post Jun 27 2017, 05:51 PM
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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.
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