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Shakercars's 1972 Trans Am

2019 August
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Hi every body l have a 94 Trans-am owned it 20 years keeps cutting out replacedfuel pump relay fuel filter coil ignition module still cuts out did a cars and coffee meet 50 miles round trip on way back to the ranch cuts out started on fourth attempt got me home 20 miles never missed a beat. Any ideas guys 

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2 hours ago, J summers said:

Hi every body l have a 94 Trans-am owned it 20 years keeps cutting out replacedfuel pump relay fuel filter coil ignition module still cuts out did a cars and coffee meet 50 miles round trip on way back to the ranch cuts out started on fourth attempt got me home 20 miles never missed a beat. Any ideas guys 

Welcome to FP! How many miles? No codes I presume? Not knowing the miles or if there are any codes, it is possible that there’s an injector issue or an IAC valve issue.

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Your car has the LT1 V8 engine, as does my Buick Roadmaster. However, the Optispark ignition is often consider this engine's Achille's Heal. The problems you are reporting are consistent with what previous other LT1 owners have reported. I suspect your Optispark is starting to fail. I know some guys have also reported bad replacement Optisparks out of the box too. So I would recommend looking up a quality manufacturer as a replacement. 

I have been fortunate with my Buick, it still has the original OEM Optispark in it at 127k miles.

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23 minutes ago, Frosty said:

Your car has the LT1 V8 engine, as does my Buick Roadmaster. However, the Optispark ignition is often consider this engine's Achille's Heal. The problems you are reporting are consistent with what previous other LT1 owners have reported. I suspect your Optispark is starting to fail. I know some guys have also reported bad replacement Optisparks out of the box too. So I would recommend looking up a quality manufacturer as a replacement. 

I have been fortunate with my Buick, it still has the original OEM Optispark in it at 127k miles.

Good catch Frosty! I forgot about that setup! That was a somewhat short lived technology I never really got into. Kind of like fiber optics, which i did do a lot of work on, is a great idea, but the level of precision and maintenance is too encompassing!

Edited by Last Indian
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Thought I'd add this article for reference too.

https://www.lt1howto.com/articles/optisparkfaq.htm

Sounds like MSD or Dynaspark are the go to replacement items - per the article.

 

 

 

 

Edited by Frosty

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The Opti Spark on a LT1 can be troublesome Especially the unvented units 1994 and earlier....Before you rush out and buy one...Pull the cap off of it and look at it real close 3 or 4  different times in different kinds of light ...Inside and out...Use a magnifying glass if necessary.....Pay special attention to the area around where the coil wire plugs into the cap and the area around where the wire harness plugs into it....Alot of times a hairline crack will develop in those areas and can be almost impossible too detect and/or see...And will cause intermittent drivability issues....Also pay close attention to the coil wire itself on the end where it plugs into the unit...Make sure it is not dry rotted and/or brittle.....One other thing while the cap is off make sure that it is absolutely clean inside the unit...Have seen some with little flecks of some sort minuscule crap inside that would move around occasionly with the rotor and briefly interrupt the signal between the optic laser light sensor and the optic disc...Anyway look closely at those things first... If you do wind up replacing the whole unit....Spend the extra money and get an OEM AC Delco part..... Stay away from Auto parts store Chinese stuff...Also if I'm not mistaken MSD makes a kit  (or used to) that allows you convert an unvented unit to a vented one....

Edited by TWO LANE BLACK TOP
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