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Discussion Starter · #1 ·
Hello all, I have a 93 Pontiac firebird 3.4l auto. Last winter was the first time I've ever had problems with it. The car will turn over but it wouldn't crank. I tried everything until a buddy of mine told me to take the ICM and coils off and clean them. It worked great until it happened again when I went to college. It was a heavy rain that so I was stuck at the college because it would turn over but wouldn't fire. This is the fourth time it has happened since I've had it, and I'm clueless. Taking the icm and coils off and cleaning them doesn't work anymore. I was thinking it's the coils but Idk. It's getting moisture somewhere and preventing it from firing. It doesn't do it all the time though. I have confirmed that it's not a fuel issue as it is getting fuel but no spark. I'm going to trade it in or sell it either way but I'd like know exactly what is wrong. Any ideas? Could it possibly be the ECU?
 

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Take the icm to an auto parts store and have them test it.

With your 93, you should be able to read the codes by shorting the aldl pins with a paperclip. Many codes don't light the check engine light. You could have an icm code or crank and/or cam sensor code. Or other codes.

Go to this link and download the 93 factory service manual. It has a whole section dedicated to driveability & emissions. It will have explanations of the codes and how to test. http://www.mediafire.com/?40mfgeoe4ctti

For diagnosing your car, an obd 1 scan program for your pc is a must. Our member GaryDoug has made a great one for our 4th gen cars. It's called "scan9495" It will scan for codes and do sensor data info on your 93. Get at http://www.mediafire.com/?0elo4c935uc5s

You will need the net framework 4 or newer on your computer for the program to work. There's a folder with this at the linked site.

Get the v-6 version. You will need a cable to hook car's aldl to usb port of pc based computer. Laptop or notebook is best, but desk top will work iN A PINCH. Get cable at http://www.aldlcables.com

Get the 12 pin cable. Even though your car doesn't run, using scan9495 on sensor data while you crank engine will give you lots of data that might be useful in troubleshooting your problem.

Have you actually checked to see if spark was present on several cylinders?

Here are some more tools you will need for troubleshooting. Digital multimeter, spark tester, noid light or 2 lead test light, fuel pressure gauge.

Low fuel pressure or your fuel injectors not opening will keep you from running also. Some codes cut fuel injector pulse off.

Also, does your security light come on when you turn the key on? Then cycle off after a few seconds? If yes, this is normal. Vats security is working as it should. If security light stays on, then car won't run. From factory, security light on meant injectors don't open and starter action is blocked. However, because of age of car and many owners, the starter block part of vats might have been bypassed by previous owner.
 

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Discussion Starter · #3 ·
Thank you for the input. I finally have figured out what was wrong with it. The icm is bad. I took it to advanced auto and it failed the test. I have a new one on the way so thank you!!
 
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