89 corvette CODE 42 Need advise
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From: FL
89 corvette CODE 42 Need advise
Hi to all, My 89 vette is running ruff for about a week. When I went to pass someone it had no power and then when I parked it it would not start. So is it the ECM? I have changed modular,tune up cap,rotor, plugs wires. And it's still do it. (not as bad) Pulled codes got
42. Not sure to buy new ECM or not. Need advise
42. Not sure to buy new ECM or not. Need advise
Last edited by rays96in; Mar 11, 2016 at 12:23 PM.
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Joined: Aug 2002
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From: SANTA CRUZ CA
COPIED FROM ANOTHER THREAD:
The code is set by a lack of Electronic Spark Timing signal to the ECM. This is a white wire between the ECM and ignition coil driver(pin 12in the yellow or grey plug at ECM to pin B on the ignition module). Check your wiring between your ECM and ignition module including a close check of the connectors. The wiring is likely good but if you have had a connector gasket fail there could be corrosion in the connector causing a failure.
You could also have a short between the high and low resolution lines from the Optispark. This also could be a wiring/connector issue or a failed Optispark. It is hard to say.
This may be a simple problem that is difficule to track down. A factory service manual would be worth a lot to you at this point.
The code is set by a lack of Electronic Spark Timing signal to the ECM. This is a white wire between the ECM and ignition coil driver(pin 12in the yellow or grey plug at ECM to pin B on the ignition module). Check your wiring between your ECM and ignition module including a close check of the connectors. The wiring is likely good but if you have had a connector gasket fail there could be corrosion in the connector causing a failure.
You could also have a short between the high and low resolution lines from the Optispark. This also could be a wiring/connector issue or a failed Optispark. It is hard to say.
This may be a simple problem that is difficule to track down. A factory service manual would be worth a lot to you at this point.
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From: FL
I checked the white wire all looks good, I check the timing wire (that you unplug when timing car) that's good. I think I would have to pull ECM out and your saying check the plug connectors there. I have Manual
Last edited by rays96in; Mar 11, 2016 at 12:53 PM.
Drifting
Joined: May 2013
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From: Reno Nevada
Code 42 can also be set if the brown wire has been disconnected to set timing. Have you set timing recently?
See here.
http://www.chevythunder.com/est_code_42.htm
See here.
http://www.chevythunder.com/est_code_42.htm
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From: FL
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From: FL
Drifting
Joined: May 2013
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From: Reno Nevada
I can get you a set of 24's for $150.
http://www.ebay.com/itm/7-4L-V8-3500...RTc72f&vxp=mtr
Then send me the memcal (AKA PROM) to be reprogrammed for $65. Check injectors first. If you do buy injectors make sure Martin knows it's for TPI.
http://www.ebay.com/itm/7-4L-V8-3500...RTc72f&vxp=mtr
Then send me the memcal (AKA PROM) to be reprogrammed for $65. Check injectors first. If you do buy injectors make sure Martin knows it's for TPI.
Thread Starter
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Joined: Dec 2011
Posts: 84
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From: FL
I can get you a set of 24's for $150.
http://www.ebay.com/itm/7-4L-V8-3500...RTc72f&vxp=mtr
Then send me the memcal (AKA PROM) to be reprogrammed for $65. Check injectors first. If you do buy injectors make sure Martin knows it's for TPI.
http://www.ebay.com/itm/7-4L-V8-3500...RTc72f&vxp=mtr
Then send me the memcal (AKA PROM) to be reprogrammed for $65. Check injectors first. If you do buy injectors make sure Martin knows it's for TPI.
Team Owner
Joined: Jul 2004
Posts: 28,521
Likes: 3,310
From: Hartford WI
The code is set by a lack of Electronic Spark Timing signal to the ECM. This is a white wire between the ECM and ignition coil driver(pin 12in the yellow or grey plug at ECM to pin B on the ignition module). Check your wiring between your ECM and ignition module including a close check of the connectors. The wiring is likely good but if you have had a connector gasket fail there could be corrosion in the connector causing a failure.
You could also have a short between the high and low resolution lines from the Optispark. This also could be a wiring/connector issue or a failed Optispark. It is hard to say.
This may be a simple problem that is difficule to track down. A factory service manual would be worth a lot to you at this point.
You could also have a short between the high and low resolution lines from the Optispark. This also could be a wiring/connector issue or a failed Optispark. It is hard to say.
This may be a simple problem that is difficule to track down. A factory service manual would be worth a lot to you at this point.
That would be a trick but my money is on anything BUT the optispark since he doesn't have one.
IMO, the FSM is worth it at almost any point. Saved me a lot of headaches.
Team Owner
Joined: Jul 2004
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From: Hartford WI
Lets try this. Next time you start the car, get the timing. It should be more than 6 degrees. After which, disconnect the tan wire and it should drop to 6 degrees. You probably will have to rev on the motor to keep it running if it doesn't/
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From: FL
This is something new only started last week. Car runs fine until you stomp on the gas. Then when you let off passing gear it runs ok then i went in a store n came out n car would not start. So i thought my fuel pump went put new in that was not it so i tuned it up and that was not it so i changed modular n that not it. so that's why i am asking u guys what's up. I was thinking injectors were dirty or ECM is going bonkers.
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