'72 4.5 engine computer interchange?

[sreams]

Hey all,

I'm looking at picking up a 1972 300SEL 4.5 to go along with my 300SEL 3.5. The owner says it needs an engine computer. What years of the 4.5 engine shared the same computer? Can I take one from a '73 or '74 450SE? Thanks ahead.

-S

[Tomguy]

All 4.5's should have the same computer. In fact, I tested a 3.5's computer on my 4.5 and it ran fine. Fuel mapping might be slightly different, and the 3.5 ECU doesn't have the 10% full throttle enrichment of a 4.5's, but otherwise a 3.5 ECU will run fine on a 4.5!

[cth350]

All the 4.5 boxes interchange. Don't replace a 3.5 box with a 4.5 or vice versa. Also, the 2.5 & 2.8 motors have different boxes. The circuitry is roughly the same across the board, but things won't work right.

-CTH

[brownrestoratio]

you say all 4.5's ECU's are the same, does that mean a ECU from a 1977 450se will interchange and funtion properly in a 1973 450se?

[billrei]

A 77 M117 motor should have the CIS FI not Djet.

[Aaron]

I have a good, used 4.5 brain at the shop. E-mail me at Benzpower@aol.com for details.

[Chaosmosis]

A lot of techs misdiagnose a computer problem when the issue is a sensor or wiring, what is the symptom???