SwedeSpeed - Volvo Performance Forum banner

Possible to swap an R and non-R ecu?

5817 Views 18 Replies 6 Participants Last post by  300+_T5R_855
I thought i had read somewhere that the main difference in power outputs from the "turbo" and "r" model 850s is all in the ECU, is it possible to swap in an R ecu?

Does the ECU also control transmission data/information? I ask because i am wondering if it matters if the ECU came off of an auto car and is going into a manual car, or vice versa.

Yes, i did a search on "ecu" and came up with nothing.
1 - 19 of 19 Posts
Re: Possible to swap an R and non-R ecu? (nextproject)

You can't put an auto ECU in a manual car and vice versa as far as I know
thanks for the input, thats kinda what i expected, but i didnt know if the transmission control was done via a separate computer.
Transmission control is done via a separate computer in the ECU box with an Aisin-Warner logo on it.

You can certainly use the auto ECU in the manual car but it doesn't run perfectly - it tends to dump fuel when you get off the gas (runs a bit rich) and most of the time they give you a CEL for "missing TCU signal." The Euro/UK spec ECUs seem to not have this problem.

Manual computer in an auto car I'm not sure about.
has anyone installed an R ecu into their non-R 850 though?
Re: (nextproject)

Quote, originally posted by nextproject »
has anyone installed an R ecu into their non-R 850 though?

What's the point?
To get a rousing 4 or so hp for 30 odd seconds at a time?
I think maybe JRL and I have misunderstood this post a bit. Do you mean you want to put an R ECU into a naturally aspirated, manual 850? B/c in the U.S. there were no turbo, manual 850s unless it's imported from Canada or has been manual swapped.
If this is the case then forget it. You can't put a turbo ECU into an NA.
no, no, im talking about a non-T5 volvo 850 Turbo. I was under the impression that since my car is an auto, if i found an auto trans, R-model ecu that it would be swappable. Since most of the gains the R got in the power dept are from the ecu tuning on that specific model. (Boost pressure, timing, fuel maps, etc etc.)
Re: Possible to swap an R and non-R ecu? (nextproject)

An 850 turbo and an 850 R engine are different.
If it was from a 97 R into a 97 T5 perhaps
i see, well im glad i asked first. just saved myself a little bit of money and possibly some engine damage. i'll just save the dough for a reflash. thanks!
Re: Possible to swap an R and non-R ecu? (JRL)

Quote, originally posted by JRL »
An 850 turbo and an 850 R engine are different.
If it was from a 97 R into a 97 T5 perhaps

Woah, people do this on Volvospeed all the time! It's perfectly fine to do so. If what "Big Will" said it true about the transmission control, then it's fine.

You'll go from 222hp to 240hp which is a jump of 18hp. The boost goes from 10psi to 12psi. You'll feel the difference.
really? is there any way to decipher between model years with the ECU number? Well that'd be great then, im just so new to volvos, they seem simple enough, im coming from VWs as of right now (still have the corrado). Alrighty i guess it cant hurt to try then. If a check engine light pops up then i'll just swap em back and resell the ECU.
I'm an S60 guy, so if you want a straight answer to that, you should check out volvospeed.com. There is a ton of information for S70/850 Volvos, and they definitely can give you a straight answer.
Alright, Jim is right that the 850 Turbo and 850 R use slightly different engines but I don't believe the internal differences are anything to worry about. The Turbo is a '95 and the R is a 96 I assume?

I would say the slightly greater concern for you is whether the car you are putting the R ecu into has EGR or not. If it does and the ECU you put in does not then no problem. If it's vice-versa then you may throw a code for the ECU looking for EGR inputs.
the turbo is a '96. the R ECU is a 96-97. So both are OBDII.
Re: (nextproject)

Quote, originally posted by nextproject »
the turbo is a '96. the R ECU is a 96-97. So both are OBDII.

It should work. The turbo is the same (15g) and the only reason there is a power difference is the difference in boost between the T5 and the T5-R/R.
It'll work fine (12psi instead of 10). There's a lot of bad info in this thread.

Manual ECU will not work in an auto. It can't communicate with the TCU.

Auto ECU will work in a manual, but you'll throw a code saying, "hey, where's the automatic transmission?" And the arrow will flash on the dash. You'll also get into weird problems during shifts. Auto ECUs don't know what to do all of a sudden when the clutch goes in and there's no load on the engine. Like someone else said, it runs rich for a split second. But people have ran auto ECUs in manuals for years with no serious problems.

The only thing you have to worry about is EGR in 850 turbo ECUs. '94-'95 had EGR, '96-'97 didn't. So if you put a '96-'97 ECU in a '94-'95 car, it'll throw a code for the EGR. When you get into X70 ECUs from '98, you have to worry about SAS and blowing up the A/C, but that's a whole different story.

Don't worry about the names like T5 or turbos. Turbos were the same as T5s, just name changes over the years. Four classes - NA, LPT, HPT, R.
See less See more
Thank you a BUNCH for clarifying several things that were weighing on my mind other than the original question (such as difference between the T5 and the Turbo models).

Its all so clear to me now! Thanks again to those who answered.
Re: (Wagoneer)

Quote, originally posted by Wagoneer »
There's a lot of bad info in this thread.

Master of the understatement you are.

Quote, originally posted by Wagoneer »
Don't worry about the names like T5 or turbos. Turbos were the same as T5s, just name changes over the years.

There are slight internal differences, but none that affect what you are trying to do.
1 - 19 of 19 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top