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'97 850 GLT ECU swap to T5

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

503GLT
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503GLT

'97 850 GLT ECU swap to T5

Post by 503GLT » Wed Nov 20, 2019 7:11 pm

Has anyone put a 1997 850 t5 ecu into a 1997 850 glt and had good luck not prematurely ruining the engine/ turbo/ etc?

I guess ultimately I’m wondering if it’s worth it, and if people have had experience doing this swap with the same year car and equipment and had feedback on it.

Am I potentially facing blowing head gaskets, or a turbo? Should I just leave my clean reliable GLT as is?

Thanks!



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erikv11
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erikv11

Re: '97 850 GLT ECU swap to T5

Post by erikv11 » Wed Nov 20, 2019 9:12 pm

Dozens of people have dropped the standard T5 ECU into a GLT (LPT) 850 or x70 without blowing anything up. My 98 V70 is an example. In fact your engine is slightly higher compression than a T5 engine. However ...

(1) The small turbo on your car will not be able to produce the boost the T5 tune calls for and you won't notice a difference. You need to put in a 15g from a 97 T5, or you could get a 16t it is nearly the same unit.

(2) The 97 is a weird year for AC and ECUs, and people have not figured it out as far as I can tell. Chuck W on this forum may know the story better. If you do put in a T5 ECU, especially from a 97 T5 which is Motronic 4.3, then make very sure the AC compressor is not running all the time. If it is then you can't run a 4.3 ECU without frying the AC compressor. You can just pop in the 97 ECU to test this.

(3) In addition to the 15g turbo, you must put in the fuel larger (higher flowing) injectors the ECU is expecting. Otherwise the engine runs lean (very bad) and/or the fuel trims are very high to compensate. You can;t skimp on this, you must put in the orange injectors from a 94-97 T5. I have spares if you want them, cheap!

(4) Your GLT runs Motronic 4.4 and the 07 T5 runs Motronic 4.3. M4.3 is slower to start up and has some other minor disadvantages. A 98 M4.4 ECU might be a better choice, although there you have the opposite problem with the AC, it will never work.

(5) If the smog setup is different on the two cars, you may get a nuisance CEL for that.

There is no harm at all in dropping it in and driving around the block to satisfy your curiosity, but long term you have to consider these points. And for sure check the AC compressor at first startup if you drop it in.


'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 140k
'98 S70 NA, 210k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 280k
'06 S60 R, 160k
gone: '96 NA 850 210k, '98 NA V70 182k

503GLT
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503GLT

Re: '97 850 GLT ECU swap to T5

Post by 503GLT » Wed Nov 20, 2019 9:25 pm

Thanks erikv11 -- I put the ECU in last weekend, and since there is so much traffic here all the time, I've not really been able to test it. What I have found is the AC does work, but I guess you're suggesting I just don't run it all the time? That may be an issue for two reasons (1. I'm always having to defrost in the winter 2. I like to run it cold in the Summer most of the time, and on road trips will run it almost 100% of the time)

I have noticed some increased boost, but to your point about the injectors, I think I run out of fuel at some point, as it seems to be looking for more. If I ease into acceleration then punch it, the wheels will light up with ease! And as you'd mentioned about ignition, it does take an extra chug to turn over.

Assuming I don't upgrade the turbo (for now) and just get the orange injectors from you (which I'm very interested in) do you think this swap is worth doing? It almost seems like I'm just creating some future problems for a low mile (120k) and super clean car that I'm not going to glean that much from in comparison to keeping it out of the shop, or tinkering in the driveway all the time.



Chuck W
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Chuck W

Re: '97 850 GLT ECU swap to T5

Post by Chuck W » Wed Nov 20, 2019 9:47 pm

Yeah, we have a '97 GLT and dealt with this stuff. The '97 GLT is an M4.4 ECU, but is an oddball in regards to the AC command routines with the other M4.4 (98MY) units. They are coded differently.

It's not worth the risk to the AC to drop the '97 T5 M4.3 ECU in there. You'd be better off with one from a '98 T5. You still won't have working AC, but it is an actual M4.4 ECU.

Erik covered many of the other details (injectors, turbo size, engine compression) which should be considered.

Depending on your skill level, you could flash your own ECU (See the M4.4 Wiki HERE) with what is basically a '98 T5 base tune, tweaked for the '97 GLT. (The noted software "AC Mod" on the wiki there does NOT work for the '97 GLT).

This is what I wound up doing on the wife's '97 GLT, but it took A LOT of extra leg work to get things sorted out and to have working AC. Her car is running an '01 LPT motor (like the '97 GLT, just newer), with a 16T and upgraded exhaust, blue injectors. Running boost somewhere between the GLT and the T5 (Just haven't had too much time to play with it). It has working AC and goes like stink.

Since we don't know your skill level, it's really hard to suggest a route for you to take.



Chuck W
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Re: '97 850 GLT ECU swap to T5

Post by Chuck W » Wed Nov 20, 2019 9:49 pm

The problem isn't running the AC/Defrost. It's the fact that the compressor will most likely NOT shut off when it should, especially at higher RPM/WOT.
Seeing as you use/want the AC to function, put the original ECU back in.



503GLT
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503GLT

Re: '97 850 GLT ECU swap to T5

Post by 503GLT » Wed Nov 20, 2019 10:20 pm

I’m mechanically inclined, but my skill level and tool library is pretty novice when it comes to the 850. I was more well versed with my 240, but when it comes to computers and electronics, I kind of freeze. I love the little bit of added pep this ECU has given the GLT, but you’re probably right about not breaking other parts of the car for this.

If it was somewhat simple to make the a/c work, I would consider adding a larger turbo and injectors, but I’m guessing all of this probably isn’t the smartest route.



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erikv11
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Re: '97 850 GLT ECU swap to T5

Post by erikv11 » Thu Nov 21, 2019 12:15 am

Chuck W wrote:
Wed Nov 20, 2019 9:47 pm
... This is what I wound up doing on the wife's '97 GLT, but it took A LOT of extra leg work to get things sorted out and to have working AC. ...
Chuck either I forgot or I never understood your solution: how did you make the AC work, was there some additional coding to an m4.4 bin?


'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 140k
'98 S70 NA, 210k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 280k
'06 S60 R, 160k
gone: '96 NA 850 210k, '98 NA V70 182k

Chuck W
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Re: '97 850 GLT ECU swap to T5

Post by Chuck W » Thu Nov 21, 2019 5:49 am

erikv11 wrote:
Thu Nov 21, 2019 12:15 am
Chuck either I forgot or I never understood your solution: how did you make the AC work, was there some additional coding to an m4.4 bin?
Erik. It took buying another -936 (97 GLT) ECU. Pulling the chip out of it. Buying the proper holder. Sending it to someone in Sweden who offered to read the bin and make the .XDF file for it (To translate the bin). Then someone in Norway, who had decoded the original "AC Mod" on VS looked things over and made a mash-up of the -607 with the -936 AC routines.

When I got that bin back, I did a quick test to make sure the AC worked like it should, and it did. I then "de-tuned" the -607 bin (98 T5) to the GLT specs, in regards to ignition/VE/turbo maps, to get a starting point. Made the changes for the new injectors (I'd stuck the original ECU /injectors back in the car while sorting this out), and disabled the diagnostics for sensors, etc that weren't appropriate for the '97 GLT vs the 98 T5. Since then I've upped the boost a bit and made some minor changes, but haven't had a chance to do any data logging.

This new engine has ExVVT on it, and I was planning on talking with Aaron at VAST to see if he can make his mods to this bin to accommodate that. Right now it's just disabled. I'd like to go COP, as well, but we may wait on that.

However, once it was finally sorted out, the AC in this car works like it should, and I can flash a tune to make any adjustments needed to account for mods, etc. Just holding off on getting silly with it, as we don't have a wideband O2 in the car. We're still in "stock" upgrades territory, but being able to adjust things for minor changes is nice.

To the OP, honestly, if you're not comfortable messing with it, I would put the original ECU back in.

I will say that we ran her car with the 16T/Japanifold/OBX exhaust for a few months on the stock ECU/injectors with little issue, aside from the fact that I could tell it would run out of fuel on the top end due to the slightly larger turbo and free-flowing exhaust. A better manifold and exhaust would give you a bit more pep, without getting too much on the edge of things.
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erikv11
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erikv11

Re: '97 850 GLT ECU swap to T5

Post by erikv11 » Thu Nov 21, 2019 10:33 pm

503GLT wrote:
Wed Nov 20, 2019 9:25 pm
Thanks erikv11 -- I put the ECU in last weekend, and since there is so much traffic here all the time, I've not really been able to test it. What I have found is the AC does work, but I guess you're suggesting I just don't run it all the time? That may be an issue for two reasons (1. I'm always having to defrost in the winter 2. I like to run it cold in the Summer most of the time, and on road trips will run it almost 100% of the time)

...
See Chuck's comments about AC under boost, but the other thing I would look at is if the AC compressor is running even though the AC is off. Lift the hood and make sure that's not going on. If it's not, you may be OK. I'd also check the see if the compressor cycles on and off intermittently the way it is supposed to. Find some use condition where AC cycles with the original ECU, then replicate that with the T5 ECU in there.

There's actually not as much data for putting m4.3 ECUs in a 97 LPT, everyone has been using m4.4. It does sound encouraging but keep an eye on it you should be fine. In the end it's your call, I don't want to be the reason if the AC compressor cooks from overuse!


'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 140k
'98 S70 NA, 210k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 280k
'06 S60 R, 160k
gone: '96 NA 850 210k, '98 NA V70 182k

503GLT
Posts: 5
Joined: Tue Nov 19, 2019 10:19 pm
Year and Model: 1997 850 GLT
Location: Portland
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503GLT

Re: '97 850 GLT ECU swap to T5

Post by 503GLT » Thu Nov 21, 2019 10:51 pm

I will be sure to check the AC for cycling, and I’d never hold anyone on here accountable for their feedback. I’m just having a hard time understanding the computer aspect, and I would think if it was this easy to gain a little boost and HP without repercussion, more people would be doing it and talking about it (but that’s not the case)

I was at IPD this afternoon and talked with one of the guys there about it. He said I shouldn’t really see a whole lot of difference until I upgrade the turbo and the injectors. So for now I’m going to switch back to the glt ECU and gather the parts.

On the cold mornings here, I have noticed quite a change in the low end— I can wind my tires up a little too easily, and the thing takes off. When it warms up outside though, it kind of bogs down, just pulling warm air into the engine.

The guy I spoke with at IPD didn’t think there should be an issue with the AC, for some reasons I wish I could remember. But I do believe that it is a common problem for most— I’ll report back once I trial it.



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