I am looking at buying a 1985 944, but it doesn't have the stock ecu, the guy I'm buying it from has a 1984 ecu.

My question is will this 84' ecu be compatible with the 85' engine? Or do I need a different ecu

 

I forgot to mention that it has a manual trans and an A/F meter

 

Nope..needs an 85 and later unit. Contact Ftech9 on here about this. You'll have to get one off of E-Bay. turbo ones are different too...won't work. You will need one with a 35pin connector. Be sure to count those..many on Ebay are the 55 pin variety. The early ECU's (DME's on here) have chips that cannot be replaced. The 85.5-to about 87 have the replaceable chip configuration you are probably looking for. You might find one for about 225-250 on E Bay. Ftech9 does upgrades on those DME's so if you need to get one, get the upgraded model from him with the OBD ports. It'l cost more, but is really the best way to go... at the present time. HTH's some..BTW..WELCOME TO THE FORUM!

 

Ok, that might save me some money on negotiations. I am fairly new to these cars. What is the difference between the 85 and 85.5 did Porsche switch things up in the middle of a year?

 

The dude that is selling it says that it is an early 1985 so I am guessing that it is not a 85.5 but I don't know how to tell

 

They're very easy to tell apart: the early 85 had the squared-off dash while the 85.5 (and on) have the elliptical dash.

 

To further complicate things it (supposedly) doesn't matter what ECU you have, as long as you have the correct AFM to match.

 

would this be considered an 85 or 85.5 it is the only pic of the dash. I'm assuming it is an 85 because it has 3 round gauges and the 85.5/86 model does not. In this case, would the 84 ECU (DME) work since it isn't a 85.5 and up?

 

Early (85).

 

85.5 looks like this:

 

so would the 84 ecu work then? or do I need an 85 and up ecu (DMS)

 

Get the part # off the AFM and find out if it's a late or early model, and get the ECU to match. The factory parts catalogs are downloadable from the Porsche website.

 

I guess that is something that I will do when I get the car

 

Yep! There was a totally different car that came off the line in the latter half of 1985. If you have an early production 85, then it might take the earlier 84 ECU. Either way, Tempest is correct. You need to find out which AFM you have to get the correct ECU so they will Jive together. The 85.5 cars had a different one.

 

Go to Clarks Garage website. There is a detailed discussion with p/n to avoid any confusion.