Code 42
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Joined: Oct 2004
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Code 42
My 89 has been possessed with rough idling problems. I've check for vaccuum leaks, replaced leaking injectors, and have thrown alot of money at it. I was not getting any engine lights, but I just decided to check for code anyway. Upon checking, I was given a code 42. I the replaced the electronic spark module (Little device under the rotor cap). $59.00 later, I still have the code 42. This car has a serious grip on my wallet, please help!!!
Thread Starter
Advanced
Joined: Oct 2004
Posts: 78
Likes: 0
Code 42
My 89 has been possessed with rough idling problems. I've check for vaccuum leaks, replaced leaking injectors, and have thrown alot of money at it. I was not getting any engine lights, but I just decided to check for code anyway. Upon checking, I was given a code 42. I the replaced the electronic spark module (Little device under the rotor cap). $59.00 later, I still have the code 42. This car has a serious grip on my wallet, please help!!!
I am not where I need to be, but thank God I am not where I used to be.
-Joyce Meyers
Le Mans Master
Joined: Feb 2006
Posts: 8,753
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From: Louisiana
Instructor
Joined: Jul 2005
Posts: 140
Likes: 2
From: RI
RRT vette is a very helpful guy. He has given me great advice on more than one occassion.
Definately check that est connector. Unplug it and reconnect it.
I had the same code last summer that wouldn't go away until I removed the ecm computer (under the passenger's side dash) and disconnected the wires as well as removed the chip and put it back it. I haven't had a code 42 in a while. I am convinced that it is either the wiring that plugs into the ecm or ecm itself.
When you are done checking the wires, remove the negative from the battery to clear the codes, and reconnect.
I feel your pain. God bless.
Definately check that est connector. Unplug it and reconnect it.
I had the same code last summer that wouldn't go away until I removed the ecm computer (under the passenger's side dash) and disconnected the wires as well as removed the chip and put it back it. I haven't had a code 42 in a while. I am convinced that it is either the wiring that plugs into the ecm or ecm itself.
When you are done checking the wires, remove the negative from the battery to clear the codes, and reconnect.
I feel your pain. God bless.
Last edited by 1988redvette; Jan 3, 2007 at 07:15 AM.
4th Gear
Joined: Sep 2004
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Code 42 could be a couple of other things. ECM has seen that you Electronic Spark Control is not working properly. Could be the Knock Sensor, on the passenger side of the block, or the ESC module, passenger side by the blower motor. The EST connector is for setting base timing, unplug it, set timing, and then plug it back in. Then clear codes. I bet your problem is either knock sensor or module.
Last edited by mech259; Jan 3, 2007 at 08:02 AM.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
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From: Louisiana
Sirwilliam1229, looks like you will need a good ohm meter ($10 at walmart) or VOM ($20 at walmart) and a test light ($5 at walmart) to really figure this code out. You will also need to pull the ECM from under the passenger side dash.
Look under the pass dash at the hush panel. You will need to remove three philips head screws to drop the hush panel and disconnect the light. Move some of the wiring out of the way and you will see a tan bracket with two 10mm bolts. This is what hold the ECM in place. Remove the bolts and the bracket will fall down. Gently pull on the ECM and it will come out. You will be working with the white wire (D4 the EST wire) on the larger of the two ECM connectors (32 pin). Follow the pdf from AGENT 86 in the link I provided. A pic of the location and description of the EST wire is in your thread in Scan and Tune section. Remember to reset the ECM by disconnecting the battery or pulling the ECM fuse when you think you have it figured out. Start the engine and let it run for at least one minute to see if the code is gone or reappears.
Chris, thanks for the kind words...did you ever figure out your fuel problem?
Look under the pass dash at the hush panel. You will need to remove three philips head screws to drop the hush panel and disconnect the light. Move some of the wiring out of the way and you will see a tan bracket with two 10mm bolts. This is what hold the ECM in place. Remove the bolts and the bracket will fall down. Gently pull on the ECM and it will come out. You will be working with the white wire (D4 the EST wire) on the larger of the two ECM connectors (32 pin). Follow the pdf from AGENT 86 in the link I provided. A pic of the location and description of the EST wire is in your thread in Scan and Tune section. Remember to reset the ECM by disconnecting the battery or pulling the ECM fuse when you think you have it figured out. Start the engine and let it run for at least one minute to see if the code is gone or reappears.
Chris, thanks for the kind words...did you ever figure out your fuel problem?
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
Assuming your Check Engine Light is working, the Code is History; ie, left over from whenever or whomever last checked the timing (and if you are in an Emissions State like CA where they check timing) leftover from your last smog check. Clear it and if it doesn't come back, you've solved the problem. Otherwise, do the easy stuff first and make sure that your Check Engine Light is working. Should be a bulb check everytime you turn on the key. Disconnect the TPS with it running and verify that it will spit out a 22. Inspect the barrel plug connector (some have posted that they've crumbled with age) and wiring. Make sure the Prom is fully seated (especially if you've replaced the ECM) - remove and reinstall.
As to your rough idle, check compression on #7; inspect the spark plug to make sure it looks like #5 and that there's no rust on the threads.
As to your rough idle, check compression on #7; inspect the spark plug to make sure it looks like #5 and that there's no rust on the threads.
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Brett Foote
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Joined: Jul 2002
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Hi man our vette had code 42 too! we changed esc module, injectors etc etc last thing we checked was the ecm. I borrowed one from a friend and it started right up. Please check the ecm especially if your finding the spark plugs soaked with fuel.