Early C4 ECM

[EJSC4]

Many thanks for your help. I think you are correct in that the ECM were the same. My problem now is to find someone who can supply a prom suitably programmed. Will let you know how I get on.

 

[EJSC4]

I have attached below the full GM engineering specs in PDF format for the design and build for 1984 C4, about 100 pages

Download and save as it has all the design specs for 1984 Corvette
As you mentioned and all I see different is to engine is supported leaded gas

I would not think they would have a different ECM just for that, as the changes for fuel itself would be in the Calibration in the E-prom
Smog items like CATs or O2 sensors would also be just changes to the calibration

If anything, I would assume many years ago that 84 Vette switched to unleaded gas and best case they then switched to harden valves for
unleaded

Still having issues with ECM/prom. Can you supply a new prom? I have found someone who has a prom reader and can give me the readings and also program a new one, but he would need the codes. Many thanks for your help

 

[teamzr1]

As mentioned, the 1984-85 C4 used its own ECM design and calibration
Due to only those 2 years, there is not any tuning programs to change the calibration

There are a few vendors still selling the 1984 E-Prom like this

84-93 ECM Eprom / Memcal Chip *Specify Year & Transmisson* | Corvette Central

* Originally not designed to last over 5 years, as a result Corvettes equiped with eproms need to be replaced or flashed every 5 years to maintain peek performance. * Eproms are newly reflashed OEM parts. The software contains the latest upgrades that are available including running changes...

www.corvettecentral.com

On top of the E-prom should be a 4 number prom code, when ordering a new one make sure selecting the same code
using this list :

C3-C4 Corvette EPROM & Memcal Chip Codes 1980-1995 | Dino's Corvette Salvage

What an EPROM or Memcal chip is, and how those chips store the tune for C3 and C4 Corvette engine computers.

www.corvettesalvage.com

Your ECM is either one of these 2 so look at what your GM part 3 is

1226430​

16006630 : N82S181 1K*8 PROM pinout​

	1 24​ 2 23​ 3 22​ 4 21​ 5 20​ 6 19​ 7 18​ 8 17​ 9 16​ 10 15​ 11 14​ 12 13​
A7​	VCC
A6​	A8
A5​	A9
A4​	~E1
A3​	~E2
A2​	E3
A1​	E4
A0​	D7
D0​	D6
D1​	D5
D2​	D4
GND​	D3

Application:​	1983-84 5.7 V8 CFI “8” L83 w/ MT 1983-84 5.7 V8 CFI “8” L83 w/ AT (Canada)
MEMPAK IDs:​	CDF, CDK, CFB, DBP, DBR
Program ID:​	22 ($16)
Pgm ID Addr:​	$3002
Scan ID Addr:​	$33F8:$33F9
PROM type:​	N82S181
PROM offset:​	$3000

1226026​

Application:​	1983-84 2.0 L4 TBI “P” LQ5 1983 5.0 V8 CFI “S” LU5 1983-84 5.7 V8 CFI “8” L83 w/ AT (exc. Canada)
MEMPAK IDs:​	“P”: AMR, CDS, CDY, … “S”: ALL, ALM, CHH “8”: CCC, CDR
Program ID:​	15 ($0F)
Pgm ID Addr:​	$3002
Scan ID Addr:​	$33F8:$33F9
PROM type:​	N82S181
PROM offset:​	$3000

 

[EJSC4]

As mentioned, the 1984-85 C4 used its own ECM design and calibration
Due to only those 2 years, there is not any tuning programs to change the calibration

There are a few vendors still selling the 1984 E-Prom like this

84-93 ECM Eprom / Memcal Chip *Specify Year & Transmisson* | Corvette Central

* Originally not designed to last over 5 years, as a result Corvettes equiped with eproms need to be replaced or flashed every 5 years to maintain peek performance. * Eproms are newly reflashed OEM parts. The software contains the latest upgrades that are available including running changes...

www.corvettecentral.com

On top of the E-prom should be a 4 number prom code, when ordering a new one make sure selecting the same code
using this list :

C3-C4 Corvette EPROM & Memcal Chip Codes 1980-1995 | Dino's Corvette Salvage

What an EPROM or Memcal chip is, and how those chips store the tune for C3 and C4 Corvette engine computers.

www.corvettesalvage.com

Your ECM is either one of these 2 so look at what your GM part 3 is

1226430​

16006630 : N82S181 1K*8 PROM pinout​

	1 24​ 2 23​ 3 22​ 4 21​ 5 20​ 6 19​ 7 18​ 8 17​ 9 16​ 10 15​ 11 14​ 12 13​
A7​	VCC
A6​	A8
A5​	A9
A4​	~E1
A3​	~E2
A2​	E3
A1​	E4
A0​	D7
D0​	D6
D1​	D5
D2​	D4
GND​	D3

​

Application:​	1983-84 5.7 V8 CFI “8” L83 w/ MT 1983-84 5.7 V8 CFI “8” L83 w/ AT (Canada)
MEMPAK IDs:​	CDF, CDK, CFB, DBP, DBR
Program ID:​	22 ($16)
Pgm ID Addr:​	$3002
Scan ID Addr:​	$33F8:$33F9
PROM type:​	N82S181
PROM offset:​	$3000

1226026​

​

Application:​	1983-84 2.0 L4 TBI “P” LQ5 1983 5.0 V8 CFI “S” LU5 1983-84 5.7 V8 CFI “8” L83 w/ AT (exc. Canada)
MEMPAK IDs:​	“P”: AMR, CDS, CDY, … “S”: ALL, ALM, CHH “8”: CCC, CDR
Program ID:​	15 ($0F)
Pgm ID Addr:​	$3002
Scan ID Addr:​	$33F8:$33F9
PROM type:​	N82S181
PROM offset:​	$3000

The ECM is no.1226430 Prom no.CFB8577

 

[teamzr1]

Here is a vendor that sells older Corvettes E-Proms so contact them of the other 2 vendors I listed above

gmeprom.com home

eproms for gm vehicles

gmeprom.com

There were 2 versions of the E-Prom for auto tranny, you have now, I marked what the newer one is

I listed all ECMs and proms for 1984, ask vendors above for one best suited for your '84





There was 1 GM TSB related to the Prom yours is