ECM I Assume
Thread Starter
Intermediate
Joined: Dec 2014
Posts: 25
Likes: 3
From: Texas
ECM I Assume
So I recently "acquired" an 81' that's still mostly stock. The air pump is gone, but the rest of the ccc system was there with the carb feedback unplugged. It of course ran like crap, so the carb has been rebuilt, all the loose vacuum lines replaced, everything hooked back up as it should be, and runs decent when it's cold. Problem is, once it's been run a little and heat soaks for 10-15 minutes, she doesn't want to start, idles up to 2000K, and develops what sounds like a rich miss-fire.
After taking the tape off that was covering the CEL, pulled codes and get a laundry list 14/15/44/45/54/55, the first four of course contradict each other!
So....ECM I think...yes? Especially with the 54/55.
Thanks!
David
After taking the tape off that was covering the CEL, pulled codes and get a laundry list 14/15/44/45/54/55, the first four of course contradict each other!
So....ECM I think...yes? Especially with the 54/55.
Thanks!
David
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
David.
I would NOT just go buy an ECM ....UNTIL you have verified and fixed these codes first by checking all the circuits. Not writing that the codes have to go away...but KNOWING the wiring is good is important. Because if you go and put another ECM in...you can have the same problem.....AND I am NOT writing that the ECM is NOT the fix (possible along with another new chip)...but with the codes you have...I would HAVE TO check the wiring first and verify the ECM is getting power and GOOD grounds. Then crank it with a scanner on it and see what it does.
http://www.lbfun.com/warehouse/tech_...1981_Codes.pdf
DUB
I would NOT just go buy an ECM ....UNTIL you have verified and fixed these codes first by checking all the circuits. Not writing that the codes have to go away...but KNOWING the wiring is good is important. Because if you go and put another ECM in...you can have the same problem.....AND I am NOT writing that the ECM is NOT the fix (possible along with another new chip)...but with the codes you have...I would HAVE TO check the wiring first and verify the ECM is getting power and GOOD grounds. Then crank it with a scanner on it and see what it does.
http://www.lbfun.com/warehouse/tech_...1981_Codes.pdf
DUB
Thread Starter
Intermediate
Joined: Dec 2014
Posts: 25
Likes: 3
From: Texas
Checked grounds, cleaned connectors, checked all continuity...all good. ECM cleared it all up, but may have been that the prom was loose. Either way the CEL is off without putting the black tape back that was covering it!
On a separate note, it still didn't run right once it heat-soaked, so upon further investigation I found the rotor tang broken off and a half inch hole burned through the cap from the lightning storm in the dizzy. A testament to the power of HEI as I can't believe it ran at all like that
On a separate note, it still didn't run right once it heat-soaked, so upon further investigation I found the rotor tang broken off and a half inch hole burned through the cap from the lightning storm in the dizzy. A testament to the power of HEI as I can't believe it ran at all like that
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
DITTO the last post. Over the years, the ground connections and the socket terminal contacts can get corroded. Cleaning them WELL is the FIRST thing to do. Then, if you still have the same codes, check them out & repair as necessary. The diagnostic diagram indicates that if ALL else fails, change the ECM.
