So i have a 92 3.1 currently, but i found a perfect 87 2.8 at a junkyard this morning. I ripped off a couple parts for it that i needed, just some bolts, castle nuts, and dust caps, probably taking a tire tomorrow as well since it has perfect rims on it, and why have a doughnut when you can have a full on tire? (how much do our stock rims cost, should i take all four?) Is there anything i should grab for sure from it thats difficult to find/get? And is there anything that definitely WON'T work between the two? as far as i could tell their twins

 

The 3.1 has some sensors that the 2.8 didn't have, the 3.1 was MAP based IIRC. Otherwise they are pretty much the same thing. The 3.1 obviously makes slightly more power as well. but the accessories will interchange without issue.

 

u cant use the intake off a 3.1 without an ecm swap .
cold start fuel is added by the cold start injector on a 2.8 , the 3.1 uses the port injectors to add the fuel, the 3.1 lower does not have the provisions for a cold start injector

 

Yup, that's right. I forgot about the 3.1 losing the cold start.

 

You can't use the intake base, but the upper plenum and runners are good. I'd grab the throttle body too. If you want to experiment with porting, the intake (minus manifold) and heads would be good to grab. If the interior is clean and colors match, look for anything that is in better shape than yours, especially things like the center console lid, pedal covers, shifter plate, HVAC controls, seat belts, etc.

 

Forgot to check over the interior but tbh mine is pretty great. Maybe pedal covers but that's not a big deal. passed on the plenum since I don't see any need for it now and hopefully not the future. But I DID grab the throttle body with the spring attached. By spring has been busted for a while and the throttle won't revert all the way to the correct idle position. Will the idle screws bet set differently, or can I just plug and play with the new one? I tried to just take the spring but apparently its a pita to get in and out and I could end up effing myself over

 

Actually I'm not sure if this is the actual 'throttle body' but this is what I took and am under the impression I need/can use.

 

Sitting here shaking my head at all the wrong info here...

The UPPER 2.8 intake and throttle body DO NOT swap to the 3.1. The TPS and IAC have different connectors, for starters, requiring a rewire. The idle air in the 2.8 is via the black pipe connecting to the TB next to the IAC. If you're going to take the upper intake and TB, you need to get this pipe WITHOUT breaking it (because they don't make replacements). The plenum DOES NOT have the alternate provision for the MAP sensor and requires creative plumbing to get a manifold vacuum signal to the MAP. The throttle body has ported and manifold vacuum (small lines) reversed compared to the 3.1.
The LOWER intake swaps just fine. There are cup plugs in the holes for the CSI system. (Engine came from a 91, VIN stamp 1ML185260)
The middle intake plenum is the same. Fuel rail doesn't swap.

Take the fuel injectors as they're almost the same between engines.

If the engine is serpentine, the water pump and accessories swap, 87+ have a different alternator from the earlier ones. CTS is the same. Oil pressure units may be different depending on the 2.8. If you want to do an AIR delete, take the pass side, 1-3 exhaust manifold, as it may not have the provision for the AIR check valve connection.

 

You're right Maverick, sorry for misinforming. I may have been out of the V6 world for a bit too long lol.

 

I appreciate all the help regardless. Thanks a lot for all the info both of you. It turns out my spring is just fine though. In the process of doing my fuel injectors(over the course of a few days due to time constraints) and my spring clings back just fine when there's no cables attached to it. What could be causing my throttle to stick open some with the cables on?