628 ECU for 850's

Post by **northernlights** » 19 Jun 2013, 16:52

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.' ?"

: 628 ECU.jpeg (21.92 KiB) Viewed 6741 times

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

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 this was before I adjusted the wastegate to 2.4 psi with my patented tool.

: Wastegate Adjusting Tool.jpeg (25.92 KiB) Viewed 6741 times

Post by **matthew1** » 19 Jun 2013, 16:59

Interesting. I'm running an R ECU in my 850 T-5. I'll go out and photograph it, get the numbers.

I need to swap the stock ECU back in to see if there is truly a difference. When this R ECU went in, I couldn't feel much difference. Complicating the situation is an MBC forcing the boost over 17psi -- in cold weather/about 15psi in hot weather -- and sometimes cutting fuel.

Post by **matthew1** » 19 Jun 2013, 17:22

Post by **northernlights** » 19 Jun 2013, 17:53

Looks like the same part number as me - he're a slightly improved photo.

: 628 ECU-2.jpeg (7.63 KiB) Viewed 6741 times

Do you happen to know what year the donor was? Your actual vehicle is a '97, correct?

Post by **northernlights** » 19 Jun 2013, 18:01

matthew1 wrote:Complicating the situation is an MBC forcing the boost over 17psi -- in cold weather/about 15psi in hot weather -- and sometimes cutting fuel.

Yikes! That seems like a lot of boost, but then again who knows how big of an operating window the system allows. Out of curiosity, have you done any 1/4 mile runs with your setup?

Post by **matthew1** » 19 Jun 2013, 19:41

It is a lot of boost. I have no idea on the 1/4 mile, but I'll find out this summer. MSD coil needs to go on (easy), then hockey playoffs need to end, then track.

Post by **mercuric** » 26 Jun 2013, 10:25

There are a number of variations of the various ECUs, including the R ECUs, for different emissions control configurations and markets. Not all have their part numbers listed in VIDA or other parts documentation.

hardware-wise, the bosch (0 261 xxx xxx) number is what matters. The volvo P0xxxxxxx number really reflects the software version loaded on the box.

The R ECU has slightly more aggressive timing in a few places, and has an "overboost" feature in it's code which allows for slightly more boost for a limited time period.

072 vs 628 WOT ignition map:

The increase in timing in the few highest load lines (right side of the map) is what makes most the difference.

Post by **matthew1** » 26 Jun 2013, 12:09

Beautiful post, Mercuric. Thank you.

I swapped my stock 1997 850 T-5 ECU back in the other day and noticed nothing. There is, if Mercuric's info is correct and I have no reason to think otherwise, a difference. I just can't notice it. Perhaps it could be sussed out on a drag strip or track, switching ECUs all day.

Take my post with a grain of salt, because like I mentioned before, I have an MBC forcing boost much higher than stock.

Post by **northernlights** » 26 Jun 2013, 17:50

mercuric wrote:The R ECU has slightly more aggressive timing in a few places, and has an "overboost" feature in it's code which allows for slightly more boost for a limited time period.

The increase in timing in the few highest load lines (right side of the map) is what makes most the difference.

Thanks for posting that - this is great information. Out of curiosity, do you happen to know what the units are for the internal load signal? I've observed similar ignition advance numbers at the corresponding rpm's shown on your graph using a scan tool while driving.