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81 vett. engine light will not come on with key.

 
richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/04/13 10:07 AM

when jumped the engine light does stay on, no cod, or flash.
I do have a volt meter,i have never used it. I got your images.  i'll get some photos.  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/04/13 06:15 PM

I got a dwell meter, put + to green wire by carb. - to ground, jumped a/b  at aldl.     meter read 60.1. turn key on, meter went to 0000. if I did it right its a bad ECM?  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/04/13 07:02 PM

sounds like it..


wait... did you have the dwelll meter set to 6 cyl scale???

reverse wires also.. to retest.. i could be backwards.. its been a while and i cannot get the book out.. its buried deep right now..  i have been searching the web for an image..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/04/13 07:06 PM

this is a far superior diagram..

C3carbiringdiagram Zps6b54ea11


i was looking for a chart like this...  this is the wrong chart... some of the numbers are correct .. i just have not had the time to splice the two of them together..

86Turbobuickecmpinout Zps4c3c64ec  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/04/13 07:10 PM

this is what your computer should look like.. the proper number.. but the wrong letters..

1224810Ccccarb81 Zps95d0e600

the letters describe the chip..

that fits down in that hole.

1224770Epromconnector Zps13678e01

note that there is a little notch out of the bottom cross rail of the ic socket.. that must line up with the notch in the IC prom chip..

and all the fingers must go in..

this is a static sensitive area..

the chip is erased or damaged at about 18 volts..

you can make over 50KV in static.. and blow the electronics right out..

one hand always on the metal box... to keep your grounded..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/04/13 07:17 PM

oh... and if you are one of the lucky guys who knows how to resolder circuit boards..   go for it.. with a base station type of solder iron..

not one of the pistol type.. ..

please. OHM the tip to all three terminals on the power cord of the solder iron base station.. so you can verify that there is NO AC VOLTAGE coming thru the tip..


Hondamainrelaycircuitboard

were you able to verify that the computer harness grounds are intact on the front bolt on the intake..

and that pins R and C both had voltage when you turned the key on...

actually pin R has power all the time..  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/04/13 07:24 PM

I have a meter. I put the dwell meter red wire on the green wire by carb. black to ground, jumped ab on aldl.  put meter on, 60.1 came up, turned key on oooo came up on meter. is it a bad ecm? or did something wrong.  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/04/13 08:01 PM

the wires at the ECM i would like you to check..

Orange on Pin R should have constant positive power..

Pink and black stripe on pin C should come on with the key..

black and a white stripe  should be grounded to the engine intake..

96F3a10d 6194 420E 9061 432A29883dd7 Zpse4d4a5bd  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/04/13 08:04 PM

if you are going to buy a ECM.. and you probably are..

don't turn in the core.. pay the core charge. you have several weeks to turn it in..

this gives you the ability to switch back and forth.. by just unplugging the harness and swapping the PROM chip..

please be careful with the prom...

check the pins for alignment.. before reinserting..

note the letters and number on the prom and the computer..

want to talk... check private messages above to the left of where you log out at..  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/05/13 09:23 AM

well every thing is good at the ECM R is hot all the time. C hot when key is on. ground is good. looks like I am going to order a ECM. thanks for letting me know about the static when changing out IC prom.  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/05/13 11:07 AM

this is the point to order the ECM... and swap the prom but wait and test a few circuits with the OHM meter set to 200 ohm scale..

we are looking for resistance over 20 OHMs...

why... because any resistance less than 20 ohms on a controlled device will damage the computer..


the reman computer will have instructions to perform this test....

can you please scan it.. and post it to photobucket or drop me an private message and email it to me.. so i can use it for others.

let me go thru the test points while the computer is disconnected..


pins

C to B   over 20 ohms

C to 4  over 20 ohms

C to E  over 20 ohms

C to 18 over 20 ohms

C to 19 over 20 ohms

you should also test 3 to 7 and verify that its the same reading as when you ohm the coolant temp sensor directly..

thats  great diagram... to bad there are so few cars that are around that still use it.. only a few 80s and 81s..

i had a camaro in many years ago.. a rodent ate part of that harness.. over by the firewall... i spliced it without taking it out of the body.. started probing it one circuit at a time for shorts..  and i got to the last one and could not find the short..  the meter was hooked up and it was still beeping in continuity test beep.. everything was disconnected on both sides of the firewall.. ( in retrospect is should have just pulled it out of the firewall and put it on the work bench)  but i was going crazy trying to find that short ..  it got to be closing time.. i put away the tools.. but i decided to leave my test leads hooked up.. so i reached over and yanked them out of the digital volt meter.  there i am holding the volt meter with no wires attached.. and its still beeping!!!!!!!!!!

that meter got retired.. don't even know what i did with it..  i had actually blown it up the week or two before over at a friends house.. working in his circuit breaker box measuring the draw on the various circuits.. forgot what i was doing and managed to hook it across both lines coming in.. while the meter was configured in AMPs..  all of a sudden.. HHHMMMMMMMMM

the only thing i could do is grab the test leads and YANK them from the meter..  it was like a shot gun going off. burned my new test leads off..and blackened the face of my meter.  i cleaned and checked the damage inside.. only burned the amp socket half way off.. since i normally used voltage.. i started using it again..  it sure did not like being hooked across the unfused lines coming into the circuit breaker box..  oh.. they were 1,000 volt rated fluke test leads with the extended reach clips.. and a beckman meter.

post what you get if you have less than 20 ohms on any of the 5 controlled circuits..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/05/13 11:24 AM

once you get the computer put back in...


jump the A and B at the ALDL... count the check engine light.. code 12 , 12, 12..  is expected..

check the dwell at the  green lead... 30 degrees at 6 cylinder scale..


when you start the engine.. the dwell should be around 26 or 28 degrees...  after about a minute.  the dwell should start to swing..  normally i expect 28 to 35 degrees of dwell at idle..  and when you take it  SLOWLY to 2500 RPMs.. again.. 25 to 38 degrees...
drop it back to idle.. 28 to 35 degrees..

this means the fuel control is right in the middle of its range...  

don't adjust anything on the carb.. if your reading vary..  there is a specific procedure for them and special tools...  

if your reading are in the middle and they do vary with slight load changes.  you are in great shape..

if these feed back carbs are working its totally possible to get close if not over 20 MPH with a 350.. 23 MPG on a 305  and 26 MPG on the V6 versions..

post what reading you get at idle.. and at 2500 RPM..  

want to have fun.. extend the green wire and hook up your digital dwell meter and prop it up on the dash..  take it for a test drive..   and yes.. when you accelerate it will go all the way to one side.. but if you are crusing.. you should still be between 15 and 45 degrees of dwell..


there was a forum member back around 2009.. had a V6 elcamino he used for commuting in arizona.  his friends talked him into tossing out all those emission controls and horrible feed back carb..

so he installed an intake.. and a carb.. a vacuum advance hei..  oops... say forum members.. why does my elcamino now get 11 MPG.. it used to get 26 MPG.

i will have to find the instructions on exact procedures.. on carb adjustment.. its in an old computer around here i hope..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/05/13 02:23 PM

just thought you might like to view this article on rebuilding the feed back quadrajet...
there is a LOT more to the adjustments than is covered here. be sure to click thru the pictures as each one should have some text with it..

rebuilding the feedback quadrajet.. E4ME and E4MC.


http://www.carcraft.com/techarticles/ccrp_0908_qjet_carburetor_rebuild/viewall.html


these carb tech manuals are available out on the web...

Quadrajet E4ME E4MC 1

most of it covered in the corvette  factory service manuals..  and usually the factory service manual covers it better.. these were teaching manuals.. so you learned the systems..  the what when why where and how..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/05/13 02:32 PM

as a matter of fact..  the manual shown above.. is available at this link...

http://www.carburetor-blog.com/manuals/rochester_e4me_manual.pdf

tools are still VERY hard to come by..

don't forget this stuff is over 30 years old..
and the last carbs came on 1987 and a few carryover 88 model cars..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/06/13 04:56 PM

by the way.. i not only found the chiltons 7488 but i found an 81 caddy factory service manual that covers the feed back system completely..  so if you need more info.. i am set..  

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