replacement ECM (or ECU?) for my '95 Wagon

billmorrow

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one 1992 & two 1995 Roadmaster Estate Wagons
trying to work out the cause of the engine quitting intermittently the mechanic has narrowed it down to the ECM service # 16188051..
got a replacement from a wrecked '95, same service number..
my question is will this ECM need to be programmed with my VIN..?
and if so, how..?
i imagine it'll need it to be done so where can i get an ECM programmer..?
thanks..
 

HotZ28

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1996 Roadmaster Limited Collectors Edition 58k - 1996 PAU 2019 Regal GS
If the replacement ECM came from the same year, same engine and same part number, it would not require reprogramming.
 

Regal LTD Coupe

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It had to be replaced on my '93 Regal. Previous owner gave intermittent issues of the car stalling on a hot day or the AC randomly going out sometimes as reason for replacement, and it worked on this particular car. Hopefully it's not the reason the other '95 you got it out of had been scrapped!
 

robert graham

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Maybe you just have a bad Optispark?.....MSD makes a great replacement unit for about $800....
______________________________
 

billmorrow

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one 1992 & two 1995 Roadmaster Estate Wagons
Maybe you just have a bad Optispark?.....MSD makes a great replacement unit for about $800....
$800..?!! i think not.. and, just for my continuing education, please let me know what an optispark IS.. i've seen this mentioned in other places/threads but don't know more than the name.. :)
though, to admit, my white '95 wagon is undergoing some spark issue now and the mechanic has the front of the engine off (WHO in their right mind would put the distributor on the front of the engine UNDER the water pump..??)
 

billmorrow

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georgia
Buick Ownership
one 1992 & two 1995 Roadmaster Estate Wagons
It had to be replaced on my '93 Regal. Previous owner gave intermittent issues of the car stalling on a hot day or the AC randomly going out sometimes as reason for replacement, and it worked on this particular car. Hopefully it's not the reason the other '95 you got it out of had been scrapped!
other '95 was scrapped due to some unplanned incident with a tree.. :)
 

billmorrow

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georgia
Buick Ownership
one 1992 & two 1995 Roadmaster Estate Wagons
If the replacement ECM came from the same year, same engine and same part number, it would not require reprogramming.
thank you.. i had hoped this would be the case.. i won't even clean off the dirt so as to NOT get dirt in the plugs..
 

billmorrow

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georgia
Buick Ownership
one 1992 & two 1995 Roadmaster Estate Wagons
replaced the ECU on the '95 blue car, still has the same issues still gives code 16, replaced the manifold pressure MAP sensor, engine ran well, then quit with code 16 again..
don't have my list of codes handy just now but it says something about either a short to ground, a bad ground or some such but it is uncelar exactly what code 16 means..
after it quitting to thrid or forth time i gave up.. for now..
anyone have a thought on code 16..? :)
thanks..
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Regal LTD Coupe

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"Optispark" IS the distributor. Whatever you do, don't buy some cheap foreign made aftermarket distributor. Dumbest thing you could do for such a vital part. Would be better off just replacing the cap and rotor (with quality parts, if I even have to stress this again) than doing that.
 

Dirtybob

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anyone have a thought on code 16..?

DTC 16 is different on LT1 cars - Low resoultion pulse not detected, and is specific to the optispark distributor.

DTC16.1.jpg

DTC16.2.jpg

It's time to remove and inspect your opti. If it is an original Delco, rebuilding it is probably the best option (or at least salvage the mitsubishi sensor.)
Accd. to the all knowing internet, the MSD opti is not any more reliable than the cheap parts store units...
 

billmorrow

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georgia
Buick Ownership
one 1992 & two 1995 Roadmaster Estate Wagons
hello bob.. :)
thank you for the info above..
it present exactly the symptoms i am experiencing..
the engine now will crank but will not run..
i cleared DTC16 and cranked engine.. did not start..
the text above says "if vehicle still does not start, refer to chart A-3..
where might i find A-3..
please not i DO have a complete set of manuals for the'94-'96 roadmaster/chevy LT-1 cars.. i WILL look and see if i have this same info you provided..
thank you for pointing me in this direction..
 

Dirtybob

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Chart A-3 basically says to check wiring/fuel pressure, etc...
First you need to make sure the 4 wire connector to the opti is not damaged/loose.
You can also look here: 4th Gen LT1 F-body Tech Articles
A hard low resolution signal failure will not allow engine operation (no spark, no fuel injector pulses, no fuel pump operation [except prime]).
If the connector is not defective then remove and inspect the opti.
______________________________
 

Gbuster

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I agree with the others, don't use a Chinese opti in your vehicle. NAPA does sell them for $170 (Chinese p/n NNDST1803). The reman original GM (GM reman p/n 48-1833H) costs a bit more, and has a core deposit.

The company doing the reman is Dorman, and the work is done in Mexico. The guy in NAPA told me this.

You can replace by using the kit (Dist cap kit GM 10457293, Delco D8301). If you do, you'll need a torx socket (NAPA S14E4). I did this 77,000 miles ago when I first got my RM in 2013, and have had good results. Last year I had a code for no opti signal to the PCM, no start. Got new opti, and to date, have about 7000 miles on the reman GM opti from NAPA.
 

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billmorrow

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georgia
Buick Ownership
one 1992 & two 1995 Roadmaster Estate Wagons
I agree with the others, don't use a Chinese opti in your vehicle. NAPA does sell them for $170 (Chinese p/n NNDST1803). The reman original GM (GM reman p/n 48-1833H) costs a bit more, and has a core deposit.

The company doing the reman is Dorman, and the work is done in Mexico. The guy in NAPA told me this.

You can replace by using the kit (Dist cap kit GM 10457293, Delco D8301). If you do, you'll need a torx socket (NAPA S14E4). I did this 77,000 miles ago when I first got my RM in 2013, and have had good results. Last year I had a code for no opti signal to the PCM, no start. Got new opti, and to date, have about 7000 miles on the reman GM opti from NAPA.

thanks for all the help..
here is what i found from NAPA:

junk.JPG

is this the favored version from DORMAN..?
there are a bunch offered on rockauto abd other online parts suppliers.. rockauto has been great i might add but not sure which ones from rockauto are the non-chinese made junk..

have not been able to find any GM remans and no OEM from GM..

EDIT:
after changing to the local NAPA store from the one in the high rent district near me, i find this list:

with more optispark items that i could show with a screen snip..

again, thanks for the help.. :)
 
Last edited:

Gbuster

Buick RMS 1994
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I think it best to have a face to face discussion with someone at a NAPA store. Take your part numbers with you. Their database will likely reveal more detail than we can dig up on the web.

Be sure to check Impala SS and Corvette forums for opti discussions.

The part numbers I quoted were copied from my invoice, and the boxes.
Hope this helps.
 

Dirtybob

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do you know what opti is on your car now? A rebuilt oem delco is a better choice than dorman etc...
I've had acceptable service from dorman optis. There was one on my car at time of purchase but it did fail after 5 yrs. of daily driving. I exchanged it (lifetime warranty) and blueprinted the replacement the best I was able. Store manager told me they get a lot of returns on the dorman optis (not surprising). It has around 15k miles on it w/o issue. More recently I scored an oem opti and rebuilt it with an msd C&R. It has also been trouble free...

Two biggest issues I've seen with replacement optis are that they don't seal well (the o-rings are not sufficient) and they don't lock-tite the screws on the reluctor wheel.
I've also seen two different optis read 2-3 deg. apart with a timing light on the same car (same day/same tune/same rpm). I assume one of them wasn't indexed to the shaft correctly.

w/e you do, don't toss the old opti until you know what it is.
______________________________
 

billmorrow

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georgia
Buick Ownership
one 1992 & two 1995 Roadmaster Estate Wagons
good info guys, thanks.. will call the mechanic at the shop and see what is happening on the one with the opti issue and the other mechanic to suggest checking the opti on the other '95..
these cars seem to be going up in value per haggerty web site.. :)
 

Regal LTD Coupe

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I don't know why anyone would replace it unless they had a NOS factory one in box. Cap and rotor replacement is far better than putting an entire junk one in. When Cardone sent me a foreign made distributor for my Cadillac I refused to install it and they refunded my money. It's because everyone else doesn't do this that we have such junky parts in the first place.
 

billmorrow

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32
4
8
georgia
Buick Ownership
one 1992 & two 1995 Roadmaster Estate Wagons
I don't know why anyone would replace it unless they had a NOS factory one in box. Cap and rotor replacement is far better than putting an entire junk one in. When Cardone sent me a foreign made distributor for my Cadillac I refused to install it and they refunded my money. It's because everyone else doesn't do this that we have such junky parts in the first place.
SO! what is to be done if no NOS GM optispark..?
the guy workong n the white '95 says he has the original GM parts for the optispark he is working on now..
had no time today to go visit that shop, but when i do i will verify GM parts..
the other blue '95 wagon's issues are now pointing to the optispark (see above in this thread) so now what.. if i need a rebuilt optispark what to do and how can I tell the difference between a good vs. a bad optispark..? :)
what goes wrong with these optisparks that would require a whole new replacement and what ever happened to "new points, condenser, cap and rotor"..?
 

Dirtybob

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what goes wrong with these optisparks
they get water/coolant/oil inside
the reluctor works loose and gets damaged - may also damage the optical sensor
optic sensor fails
bearing wears out
C&R wears out
etc...

depending on the damage done and parts availability, you may need to replace the opti.

The fact your mechanic misdiagnosed that code16 and replaced the ECM is a red flag to me.
Friend of mine, had been working as a mechanic for 15+ years, had never seen an LT1 before and called me up to help him trouble shoot one. He also 'fired the parts cannon' but didn't fix the problem.
I'm pretty jaded when it comes to repair shops (past experience) and prefer to do as much of my own maintenance as possible.
 
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