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Swapping R ECUs in a Volvo 850

MVS Forum member northernlights started a very interesting thread about swapping in R ECUs:

I’ve often wondered if the higher output of the 850 R is due to engine internals, computer mapping, or some other factor. I know the turbo is a higher pressure in the R motor, but is that because its a different turbo altogether or is it the because the actuator rod is adjusted to a higher setting?

So, I recently installed a 628 ECU and it works great. It feels like I have a little more boost everywhere, not just for 7 seconds, 30 seconds, or whatever the literature claims. This is in a MY94 850.

If I didn’t know better I’d say either Volvo was fibbing, or something was lost in translation when they asked the Swedish engineers to explain the extra power – ‘I think he said Eh, about the same as two lutefish.?’

Swapping R ECUs

The 628 was allegedly stock for the 1995 T5-R, 1996 850R and 1997 850R. I have a list of part numbers for the T5-R ECU’s, and one of the 850R ECU’s, all from the EGR delete attachment (which is interesting in itself!)

These are the numbers I have:

1995 T5-R

  • 9146962
  • 8601043
  • 1275388
  • 8601113

1996 850R

  • 8601332

But wait…

My 628 ECU is not on this list. It is marked P001270xxx, which is most of the actual part number. My original 94 ECU (an 072) is marked P06842210 which is one of the part numbers listed on the EGR paper, so I tend to believe it is accurate.

Anyone have any other part numbers? Like I said, it sure seems stronger than 18 peak hp and I would like to know what’s giving it such a boost. And this was before I adjusted the wastegate to 2.4 psi with my patented tool. 


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