Help - no spark LT1, extensive testing...
Thread Starter
Teching In
Joined: Nov 2012
Posts: 3
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Help - no spark LT1, extensive testing... Hello everyone,
I'm about at my wits end with a 95 LT1 that wont spark! Long story short the engine was swapped into a Porsche 944 and I received the car not running. My initial thought was the Opti, so I bought a cheap one off ebay (which I have since learned is a bad idea). After installing, I still get no spark, so I followed this guide:
http://www.mainstreamtopics.com/foru...rt-diagnostic/
I got down to the step where it says to test for a pulsing ground at the white/black wire on the coil, from the ICM. With the key on, engine off, I have a ground, but it is not pulsing. Just stays consistent green. per the instructions, I ran out and got a new ICM, only to replicate the same situation.
Since that did not fix it, I also thought the coil might be bad - so I replaced that, which only resulted in a very weak positive signal coming out of the coil with key on, engine off. Still no spark, and no increase in signal when turning the engine over (testing at the coil).
So, does anyone have additional insight about something I might be overlooking here? I really dont want to buy a new Opti if I dont have too, but with a new ICM and coil, I can't think of anything else. And with the injectors pulsing and the proper voltage going into the Opti, I'm worried I'll just burn more money by replacing the Opti again.
Thanks in advance, any help is much appreciated.
I'm about at my wits end with a 95 LT1 that wont spark! Long story short the engine was swapped into a Porsche 944 and I received the car not running. My initial thought was the Opti, so I bought a cheap one off ebay (which I have since learned is a bad idea). After installing, I still get no spark, so I followed this guide:
http://www.mainstreamtopics.com/foru...rt-diagnostic/
I got down to the step where it says to test for a pulsing ground at the white/black wire on the coil, from the ICM. With the key on, engine off, I have a ground, but it is not pulsing. Just stays consistent green. per the instructions, I ran out and got a new ICM, only to replicate the same situation.
Since that did not fix it, I also thought the coil might be bad - so I replaced that, which only resulted in a very weak positive signal coming out of the coil with key on, engine off. Still no spark, and no increase in signal when turning the engine over (testing at the coil).
So, does anyone have additional insight about something I might be overlooking here? I really dont want to buy a new Opti if I dont have too, but with a new ICM and coil, I can't think of anything else. And with the injectors pulsing and the proper voltage going into the Opti, I'm worried I'll just burn more money by replacing the Opti again.
Thanks in advance, any help is much appreciated.
Launching!
Joined: Oct 2011
Posts: 284
Likes: 0
From: Dixon, IL
You can take the ICM to autozone. but have them test it about 5 times in a row to get the ICM heated up to test it properly. Also your supposed to have pulsing to the coil with the motor turning over, not KOEO(KeyOnEngineOff).
Also Im sorry to say but its very possible you got a bad opti, they rebuild old ones and the optical sensors are cheap ones. But one way to check is take your opti off, plug it in, and turn the KOEO, and turn the opti rotor,you will be able to hear the coil and injectors are pulsing.
Also could be your PCM, but not very likely, check ALL of your grounds. Especially since its a non-running swap they could have over lookid those,. Harness grounds are located on the ICM, behind the pass. cylinder head, and starter. I might be missing one but make sure all of those grounds have continuity.
Sorry to say but it sounds like the opti is a cheapo. But no need to bite the bullet and get a new one yet, do some testing and let us know what you come up with.
Also Im sorry to say but its very possible you got a bad opti, they rebuild old ones and the optical sensors are cheap ones. But one way to check is take your opti off, plug it in, and turn the KOEO, and turn the opti rotor,you will be able to hear the coil and injectors are pulsing.
Also could be your PCM, but not very likely, check ALL of your grounds. Especially since its a non-running swap they could have over lookid those,. Harness grounds are located on the ICM, behind the pass. cylinder head, and starter. I might be missing one but make sure all of those grounds have continuity.
Sorry to say but it sounds like the opti is a cheapo. But no need to bite the bullet and get a new one yet, do some testing and let us know what you come up with.
Thread Starter
Teching In
Joined: Nov 2012
Posts: 3
Likes: 0
Thanks for the insight!
so, it took 4 autozones but i finally found one that had the right connector to actually test the ICM. Unfortunately both ICM's passed the test numerous times....so the only thing left to replace is the opti correct?
Is it possible that the opti could only be partially working which would cause the injectors to pulse but not get spark?
At this point my fingers are crossed that it's just the opti...a new ECU + the programming to make it work with the 944 is not something I can afford for a while.
so, it took 4 autozones but i finally found one that had the right connector to actually test the ICM. Unfortunately both ICM's passed the test numerous times....so the only thing left to replace is the opti correct?
Is it possible that the opti could only be partially working which would cause the injectors to pulse but not get spark?
At this point my fingers are crossed that it's just the opti...a new ECU + the programming to make it work with the 944 is not something I can afford for a while.
After installing, I still get no spark, so I followed this guide:
http://www.mainstreamtopics.com/foru...rt-diagnostic/
http://www.mainstreamtopics.com/foru...rt-diagnostic/
Launching!
Joined: Oct 2011
Posts: 284
Likes: 0
From: Dixon, IL
you can rent a NOID light from orileys for about twenty bucks. it plugs in to the injector connector to check for injector pulse from the opti. But like i said man dont blame the opti quite yet, check grounds for cont. I even added an extra one, and some people have added 2 or more when doing the swap. So check to see if you have the ones I listed, and maybe add one from the block to frame. And if you dont have one from the PCM to the ICM, id add one from ICM to frame. Also, sorry to say it, but its time to start checking your PCM pinouts.
