Intermittent Error Code 42
07-23-2007, 08:58 AM
#1
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Intermittent Error Code 42
Hi all!
I just bought a red Corvette 1987 and is therefore very new to this forum - in fact, this is my first post here.
As I understand looking at the forum there are a lot of different problems with Corvettes and I would like to share the problems I am experiencing and hopefully someone here can help me out. I have a mechanical background so DIY repairs is not a problem.
Anyway the problems I have with my new Vette is the ignition/tuning. When engine is warm and after some medium/hard driving, the engine starts going really bad (choking and coughing) and eventually stops before going into emergency mode and showing error 42 (EST problems). After the car cools down everything is fine again.
This happend the first time when i had just refueled and left the gas station. The car wasn't in normal operating temperature and almost stalled. While holding the gas pedal steadily just above idling, it was just as you would turn on and off ignition and the engine revving up and down. Usually you hear exhaust bangs, but not now.
I had some problems with knocking/pinging also, but since i replaced the knock sensor the car now retards the spark as it should.
I do have one question? Since many problems seems to be due to bad fuel injectors, i measured the resistance both cold and warm. Cold resistance is about 16,5 ohms but warm one was down by 10 ohms and RISING to 17 ohms in just about a minute after engine was shut down.
Could a bad injector cause this strange behavior?
/From a kind of helpless guy in COLD Sweden
I just bought a red Corvette 1987 and is therefore very new to this forum - in fact, this is my first post here.
As I understand looking at the forum there are a lot of different problems with Corvettes and I would like to share the problems I am experiencing and hopefully someone here can help me out. I have a mechanical background so DIY repairs is not a problem.
Anyway the problems I have with my new Vette is the ignition/tuning. When engine is warm and after some medium/hard driving, the engine starts going really bad (choking and coughing) and eventually stops before going into emergency mode and showing error 42 (EST problems). After the car cools down everything is fine again.
This happend the first time when i had just refueled and left the gas station. The car wasn't in normal operating temperature and almost stalled. While holding the gas pedal steadily just above idling, it was just as you would turn on and off ignition and the engine revving up and down. Usually you hear exhaust bangs, but not now.
I had some problems with knocking/pinging also, but since i replaced the knock sensor the car now retards the spark as it should.
I do have one question? Since many problems seems to be due to bad fuel injectors, i measured the resistance both cold and warm. Cold resistance is about 16,5 ohms but warm one was down by 10 ohms and RISING to 17 ohms in just about a minute after engine was shut down.
Could a bad injector cause this strange behavior?
/From a kind of helpless guy in COLD Sweden
07-23-2007, 09:33 AM
#2
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Congrats and welcome aboard. I would think a bad injector could cause some of those symptoms. Also sounds like an ignition module. Both of these can work fine cold and then cause havoc when hot.
I'm sure you'll get some good replies, here is some reading in the mean time. 
http://members.shaw.ca/corvette86/Code%2042.pdf
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/agent86/Ignition.pdf
I'm sure you'll get some good replies, here is some reading in the mean time.
http://members.shaw.ca/corvette86/Code%2042.pdf
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/agent86/Ignition.pdf
07-24-2007, 07:44 AM
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*bump*
Thanks for the reply. I will check the injectors. I would wtill really appreciate if someone has experienced my problem and has possible other solutions to my problems.
Thanks for the reply. I will check the injectors. I would wtill really appreciate if someone has experienced my problem and has possible other solutions to my problems.
Last edited by DocFlipper; 07-24-2007 at 08:39 AM.
08-21-2007, 05:28 PM
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Problem Solved!
After some troubleshooting, i found out that when my car died (intermittent) the spark would disappear. So i replaced ignition module first, no change. Then the ignition coil, same problem. Checked all connections of course. The only thing left to replace regarding the spark was the ECM. I was able to borrow a used one prior to buying it, and after that, the car worked fine!
Let this be a lession to all. ALWAYS suspect the ECM when you have strange and intermittent problem.
After some troubleshooting, i found out that when my car died (intermittent) the spark would disappear. So i replaced ignition module first, no change. Then the ignition coil, same problem. Checked all connections of course. The only thing left to replace regarding the spark was the ECM. I was able to borrow a used one prior to buying it, and after that, the car worked fine!
Let this be a lession to all. ALWAYS suspect the ECM when you have strange and intermittent problem.
08-21-2007, 05:56 PM
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Welcome to the Forum. From What you have described sounds like the fuel injectors. The ECM does cause problems you described, so I would check the above post for the diagnostic check.
You should also check all of your vacuum hoses for poor connections and leaks.
You should also check all of your vacuum hoses for poor connections and leaks.
