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· Registered
143 Posts
Discussion Starter · #1 ·
hi guys I have a 1995 Camaro z28 auto tranny. So this has been a problem for the last few weeks. I bought two new optis the second opti started the car after I cleaned all grounds made sure all fuel injectors were pushed in right. so I put the car all back tg. and bam! no start so I took the car apart I decided to just pick up a new icm and a new coil and opti harness.. connected it all CAR STARTED!. this was lastnight. went to put the car tg again and bam no start my head is spinning. I got strong spark coming out of the coil so im sure the icm and coil work. I also have a spark coming out of the opti. ( the spark should only spark every 360 degree rotation of the crank shaft correct) ? because the only thing I noticed that is different is coming out of the opti I pulled one plug and held it close enough to opti to see the spark. and it will spark every second or so its not rapid.

thank you any questions or anything I dident make clear please point out im looking for help its hard to explain thank you!

· Premium Member
13,697 Posts
Get a spark tester, one that puts a load on the ignition system to simulate cylinder pressure. A spark that will fire in open air will many times fail when you use a spark tester. Get at most any parts store.

Have you watched the diagnosing the opti video in the sticky threads of this section. Thread has "diagnose the optispark" for the title. Watch video, run tests.

The fact that it runs when mostly taken apart, and won't run when together, leads me to believe that you are losing power or a ground somewhere in the wiring. So test the wires for proper voltage with engine mostly apart, and compare it to the readings when together.

However, if you are buying cheap opti's, you have a 50-50 chance of having received 2 bad optis from the parts source, so don't eliminate the opti as a suspect.

Also check your new opti harness. Take it off and use an ohmmeter to check for continuity, and for extra resistance caused by bad connections on the wire pins.

Another thing to check. The automatic transmission gets it's power from the same source as coil and icm. It is possible for a fault in the transmission wiring to pull voltage down at the coil and/or icm enough to cause a no start situation.

Finally, go to 4th gen section, open thread titled "GM service manuals" click link and download the 94 factory service manual. It shares over 95% of the info with your 95. Go to volume 2, which has driveability, emissions, and electrical section. In the driveability section resides a pcm connector symptoms chart. This chart lists the proper voltages pcm connectors should have, and what symptoms occur when improper voltage occurs. Check for wires that cause a no start condition when voltage is incorrect.
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