dabeav3

My 95 TA had the check engine light come on a while back and today it started shuttering while driving and running rough (didn't think I would make it home). Put the scanner on it and got like 50 codes. Disconnected the battery and can't seem to make the codes go away. Just turn 100k so probably need to do a full tune up but want to address the issue and not just throw parts at it. Probably the Opti-spark but am looking for ideas. Thanks.

The Outlaw Kid

iTrader: (1)

What were some of the codes?

dabeav3

I didn't write them down. Unhooked the battery to see if I could get all the codes erased and start from new. If I can't get the codes to erase I guess the PCM might be bad. Thanks

shbox

Might be the scanner you are using. Some are kooky.

dabeav3

tried a different scanner with the same results. Getting somewhere around 50 codes split between current and memory. If I rescan I get a similar number of codes some different some the same. Still can't get the codes to erase after leaving the battery unhooked for two days. Took the PCM out and cleaned the connectors, grounds and hot leads and made no difference. Trouble shot the knock sensor and eveything checked out fine. Starting to think the PCM is bad. So what is the "flashing" a new one entail? Took the access cover off the PCM and there was a little white "box" plugged in. Is that the "same" as the old chip for prior installations and would it be a matter of swapping it into a new PCM rather than "flashing" it?? Car still shutters/hesitates/misses during cruising and seems worse after it has warmed up. thanks,

shbox

Possibly is a bad PCM (or maybe a grounding or power issue?). Can't imagine that many codes at one time. The little white box is the knock module. Flashing takes a programmer or a laptop/PC, cable, software and a tune.

dabeav3

Thanks much for the inputs. I cleaned all the connectors while I had the PCM out and cleaned the ground/power inputs as well so I guess its time to try a PCM.

Ed Wright

iTrader: (1)

If you know somebody with an LT1 try plugging it into their car and check for codes. Don't even need to start it. Lots of PCMs get replaced for no reason. Also plug the other PCM into your car and check for codes.

KyleW707

When my temp sensor was bad, my car was throwing around 20 codes, replaced it and all went away. Not saying that's your problem, but it's worth a shot before swapping pcm's

pillarpod

50 codes is a lot, so how many do you have if you just look at "current" codes?

dabeav3

about half of the codes are current and half memory. 13, 16, 28, 32, 37, 41, 41,43,44,45,46,47,53,55,58, 5961,63,64,65,75,83 current. 13,14,18,23,25,26,28,44,48,55,58,61,75,79,81,82,83 ,85 memory. even get 39,57,19,35,49,56,62 etc. that aren't even effective for me car. seems very weird to me that I can't erase them either so is why I was thinking the PCM. so where is the best place to get a new or used PCM flashed? thanks as always.

ahritchie

iTrader: (1)

Is it modded or stock? If you have mods, I'd get PCM for less or some other mail order tuner reflash it for around $100 custom for your setup. Otherwise, I'd buy a used PCM off craigslist or a junkyard, or better yet find another LT1 owner nice enough to let them swap their PCM just to eliminate it as a cause.

dabeav3

Unfortunately don't have anyone around with an F-body like mine (everyone wants a Toyota or Honda these days) that I can swap with. So for a used unit, does it have to be a 94 or 95 F-body with a manual trans PCM for things to work right???

dabeav3

OK, got a different PCM and got exactly the same results. CEL comes on and the car shutters while driving. Ran a scan and am still getting 50+ codes either present or stored using Shoeboxe's hook up chart. Would the opti spark going bad generate so many codes? Any suggestions/ideas would be greatly appreciated.

ahritchie

iTrader: (1)

I already replied to your other thread....opti is toast, get a GM one or MSD


EXCELLENT article on the intricacies on opti failures:
http://www.gmhightechperformance.com...ing_modifying/

fbody_brian

Check your battery connections, make sure your grounds are tight!

dabeav3

Yeah I checked out all the grounds and cleaned all the connections some time ago with no help. Its got right at 100k on it so I guess its time for an optispark, water pump and full tune up.