ECU SWAP from 850R to 850 T-5

Post by **osman** » 04 Jun 2012, 12:26

I have found a ECU from a 850R being parted out. I want to swap it into my stage 0 850 T-5.
Is there anything I am overlooking or should it just plug and play like other ECU swaps I have done.
I am interested in any thoughts, if you think I am a fool and I will destroy my motor or transmission then feel free to say so.
Has anyone else done this swap?
Do I need to swap the transmission ECM too?
Let me know.

Post by **erikv11** » 04 Jun 2012, 12:56

In general they will swap fine but the model year matters a lot. For example all 95 R models had EGR, most 96 don't, so a 95 R ECU may throw a CEL in your 96.

What year ECU?
Do the cars both have/lack EGR?
Do the cars both have/lack SAS?

Post by **osman** » 04 Jun 2012, 13:17

Yes they are the same years (96) but yes I used an ECU from a 850 with an EGR in a 97 850 without EGR and an SAS and it ran fine just threw the EGR code.
thanks for the input.

Post by **osman** » 04 Jun 2012, 13:22

I was mostly concerned if the extra HP i am expecting will somehow be too much for my drivetrain/motor etc.

Post by **jblackburn** » 04 Jun 2012, 13:35

It's the same motor/transmission/turbo between both of them; just different programming between the "R". Really, it's only a 18 hp difference at very top end, and you're probably not going to notice a difference below 4000 RPM.

But yeah, the car can handle it.

Post by **osman** » 04 Jun 2012, 14:34

So the HP boost is only in the high end, huh?
Honestly I dont drive my car anywhere near 4000 rpms.
I just figured since I had an 850r ECU available it would be alot cheaper than upgrading my own ECU.

Post by **jblackburn** » 04 Jun 2012, 14:51

Yep. If you look at the torque numbers, etc. the R's are exactly the same - which makes sense! It's the same engine with the same turbo.

The R's had a different exhaust manifold, along with the ECU programming to allow "overboost" for up to 30 seconds, to net a little more power in the top end of the engine. It is, after all, supposed to be the "performance" model. Honestly, you will probably not even notice a difference between well-taken care of T5 and an R at this age.

Post by **osman** » 04 Jun 2012, 16:14

Thats good to know. I was thinking as if an ECU from a 850R was like the "holy grail" of performance.
Im reconsidering the ECU swap now that I realize the negligible difference I might get.
Has anyone done this swap?

Post by **matthew1** » 04 Jun 2012, 18:04

I put into my '97 T5 a '96 R ECU a couple months ago. No difference, but I had a MBC on her already. As I understand it, the R ECU will allow higher boost before fuel cutoff, but like I said, I wasn't reaching that point before, so there is no real-world difference for me.

I think the best benefit to having two ECUs is that you can send one off to be re-flashed and still drive your Volvo.

Post by **erikv11** » 05 Jun 2012, 00:59

The only issue with swapping these ECUs is the SAS and the EGR, and the CELs that might result. If you don't care about driving around with the CEL on, then just ignore that and drop it in.

From your post I interpreted that you wanted to know what will work long term, not whether the R ECU would give your car some kind of performance gain. In that case, from what you have posted about your car, there is really no point. The R ECU has minimal (but real) differences with respect to performance anyway.

If there is a "holy grail" it is an ECU tuned to match your car's current setup and performance goals. ARD tuning is the current favorite in the community. And you can use a T-5 or R ECU, it doesn't matter, they are completely interchangeable as far as a base for tuning.