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Cadillac 3800 Swap?
http://www.pontiacbonnevilleclub.com/forum/performance-brainstorming/topic42018-40.html
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Author:  Valuvan [ Fri May 20, 2016 1:17 pm ]
Post subject:  Re: Cadillac 3800 Swap?

I am definitely interested since I already have the correct chassis mounts and good axles, plus I know the trans is in good shape. I read a couple of articles saying you had to re-drill the flexplate and the two lower engine mount holes plus grind the tab off of the lower right side of the bell housing mount. A couple of questions I had; will the starter from the 3800 mount to the 4T80 and as far as controls, If I get a 2000 Bonneville harness, will the ECM from the Bonneville 3800 control the 4t80 without programming modifications?

Author:  MattStrike [ Fri May 20, 2016 2:33 pm ]
Post subject:  Re: Cadillac 3800 Swap?

I know the 4t80 case has the starter casting bump on the side, so it will retain the factory 3800 starter. The controls I believe there is a way to get the 3800 pcm to work, however it won't just plug in and go. I'd have to search for that again.

Author:  Valuvan [ Fri May 20, 2016 3:15 pm ]
Post subject:  Re: Cadillac 3800 Swap?

That would be great; I was hoping it would work out to use the caddy trans.

Author:  Valuvan [ Sat May 21, 2016 7:00 am ]
Post subject:  Re: Cadillac 3800 Swap?

After looking into this some more I'm wondering if it would make more sense to use the Caddy PCM and have a tuner drop the 3800 parameters in place of the Northstar? I'm going to go for using the 4T80 so the shift parameters, VIN # and VATS info in the Caddy PCM would already be correct. Or would it make more sense to use the Bonneville PCM and change the trans info to make the 4T80 work, change the VIN, and disable the VATS? Just thinking out loud; I'll have to do some research. Either way, first order of business is get the engine/trans setup together and get the cradle back in the car.

Author:  Valuvan [ Mon May 23, 2016 5:05 pm ]
Post subject:  Re: Cadillac 3800 Swap?

I got the engine mounted to the trans today, just had to re-drill the flex plate for the four bolt converter and re-drill one bell housing bolt. Other than that, it bolted right up to the 4t80. I'm committed to making this work now because the guys over on the Cadillac Owners website keep saying "It'll never work, It'll never work". This IS 15 year old technology; granted it might take some trial and error but I cant believe its impossible. I was going to put a few pictures on here but cant figure out where to load them at.

Author:  MattStrike [ Mon May 23, 2016 5:36 pm ]
Post subject:  Re: Cadillac 3800 Swap?

I think the biggest limitation with using the Northstar PCM is the tuning part, or lack thereof.

Author:  Valuvan [ Mon May 23, 2016 6:40 pm ]
Post subject:  Re: Cadillac 3800 Swap?

Yeah, I'm going to stick with the Bonneville PCM and probably have some programming done to accommodate the 4T80. I'm going to the boneyard to get a 2000 Bonneville engine harness, do you know if the 1999 PCM I have is the same as the 2000 or do I need the newer one?

Author:  MattStrike [ Mon May 23, 2016 10:10 pm ]
Post subject:  Re: Cadillac 3800 Swap?

I'm not 100% sure on the '00+ stuff.

Author:  Valuvan [ Sat May 28, 2016 8:04 am ]
Post subject:  Re: Cadillac 3800 Swap?

Could not find a useable Bonneville wiring harness at the boneyard that hadn't been cut somewhere but I did find that the 2001 LeSabre forward wiring harness was the same and found one of those. Also took the front engine mount which looks the same as the Caddy and the oil filter adapter which is at a better angle that the one I had. Should be putting it all together this week.

Author:  Valuvan [ Thu Jun 02, 2016 5:51 pm ]
Post subject:  Re: Cadillac 3800 Swap?

I still have a few things to do but everything is wired up and it all pretty much matched the Caddy harness. I couldn't find a Bonneville harness in the boneyard but I did find a 2001 Lesabre and it was identical. All the wiring plugs matched up to the Caddy and according to the pin out diagrams for both, the differences are limited to the extra coil and injector wires for the V8, plus a few wires for traction control which the Lesabre didn't have. I'm sure there will be things to work out but I'll just tackle it one problem at a time. I should have everything back together tomorrow and ready for a test fire.

Author:  MattStrike [ Fri Jun 10, 2016 2:35 pm ]
Post subject:  Re: Cadillac 3800 Swap?

So I can't be the only one wondering how the project went, is it running?

Author:  Valuvan [ Fri Jun 10, 2016 4:46 pm ]
Post subject:  Re: Cadillac 3800 Swap?

I was having trouble getting past the Passkey 3 system. It would run for a few seconds and then lock itself out on the security system so I found a shop in Atlanta that will delete the VATS and program the PCM to accommodate the 4T80 settings. Sounds like he knows what he's doing and I think he's on this site and the Grand Prix forum site. (PontiacJeff) So it's all together, just waiting to get the PCM back from him and go from there.

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