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Help on a 94

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Old 06-17-2017, 02:12 PM   #1
Neutron3535
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Default Help on a 94

94 auto. I run 93octane and sometimes 91 when i have to. Bought two months ago. Stock as far as i know except i just deleted the cat. Put 1000 miles on top of the 113k it already had. Went to pass someone Goin about 75, it dropped a gear and accelerated for a second then abruptly lost feul it seemed. Guages and lights didnt show anything. Pulled over and it just sat and sputtered barely staying alive. I turned it off and on a few times until it wouldn't stay running anymore. The last time I started it, it died and it sounded like air escaped somewhere up by the intake. Not sure exactly what I heard or where it came from though. The next day it tries to turn over but won't start. Lots of possibilities so seeing if I can get it narrowed down. Any ideas?
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Old 06-18-2017, 11:57 PM   #2
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You need to get a fuel gauge on it and check fuel pressure. Also check for spark at the plugs and the coil. After you find the area of the problem we can go further.
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Old 06-19-2017, 03:10 PM   #3
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My quess is Opti.....
I know ........
I know.........
everytime something goes wrong people start bashing the opti.
Well I would start there if it were me:
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Old 06-20-2017, 10:36 AM   #4
billschroeder5842
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Quote:
Originally Posted by redcorvettedave View Post
My quess is Opti.....
I know ........
I know.........
everytime something goes wrong people start bashing the opti.
Well I would start there if it were me:
Me too...

I agree that the Fuel Pressure needs to be check, but the way to bet is on the Opti
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Old 06-20-2017, 11:33 AM   #5
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Unfortunately there is no real good or easy way to check an opti. Nothing in the FSM or anything written up to indicate if the opti is the cause of an engine not running. There are things written up on a running engine with waveforms, timing charts which is all nice but might not help you to figure out why it's not starting.

You need to figure out if the ECM/PCM is providing the DC voltage for it to operate. And then you need an O-scope and enough electronic knowledge of how to use it to find out if the low resolution pulse is being generated. This is probably a stretch for most people as well as mechanics.

I have seen some really good write-ups on the opti but there is probably a narrow window of people who can relate to it. This is usually for the ones into electronics either professionally or a skilled amateur who have been using these tools for some time.

The opti just does not pop off like a coil or ICM and easy to hang one in there and try. Replacing an opti require a good effort of a day or two, expensive and add a water pump and coolant and seals to the mix. I would like to know if everything else I can check is OK before I rip the opti out……..but that’s just me.
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Old 06-20-2017, 01:57 PM   #6
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Where are you located in case someone local to you can help?
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Old 06-20-2017, 02:04 PM   #7
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ALWAYS check fuel pressure first !!!!!!!!
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Old 08-04-2017, 04:17 PM   #8
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Quote:
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Where are you located in case someone local to you can help?
Fayetteville Arkansas.
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Old 08-04-2017, 04:17 PM   #9
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It was the optispark. Fixed. Thanks guys
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Old 08-05-2017, 09:49 PM   #10
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Do you by any chance still have the original opti spark that they took out?
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