I recently replace my 1985 2.8L V6 with an engine from a 91 3.1L.

The engine is running but seems to have a bad lag when the accelorator is punched.

The computer (ecm?) from the 2.8 is controlling the new engine, will the 85's ecm control the 3.1 engine?

shouldn't be an issue, esp when reusing the 85 induction. was the tv cable adjusted properly ( if disconnected durring swap)

and welcome to the site

Assuming you are using the induction from the '85 on the '91 long block, it should work fine. If you are using the '91 intake, you will need the '91 ecm.

shouldn't he change out the injectors and use the 3.1 injectors?

I was just thinking that. Kinda liek when you swap in the 3.4 and need to use the 3.4 injectors.

ya the injectors would do it and that's kinda of a job on these cars u gotta rip the whole intake off.

Wow, thanks for the response!

We used the induction system from the original 2.8 on the 3.1, but I can't remember if we used the 3.1's injectors. If my memory serves me, we did.

Since the post we replaced the map sensor, the o2 sensor that is on the exhaust (are there any more?), mass air flow, plugs, wires, front struts, rear coil springs, adjustable air shocks, tires and a whoooooole lot of armour all.

Can anybody tell me if there is a way to test the throtle postioning sensor?

And a list of other sensors that would affect it's performance?

1985 2.8/3.1 MPFI (This project)
1987 2.8 MPFI T-tops
1986 (350 one day!!!) new suspension

advance.AZ, & probly nappy should be able to test your tps for free. I don't know if the "map" sensor cain be tested though.

also, any way of checking what teh fuel pressure is when you punch it?

No, but tomorrow i'm going to get a gauge. Do you know if the schrader valve is like a regular tire stem or do I need a specialized tool.

I'm also going to get a multi-meter to test some of the sensor readings.

We initially took the smog control stuff off, think I could have screwed something up there?

The 2.8 induction shouldn't have a MAP sensor?!?!

its by the egr , looks like a map sensor, but not called that.

is ur engine light on tho

'85 2.8 MFI does not use a MAP sensor. Check to see if the idiot light works.

Going back through the swap, the entire 2.8 intake (from the bare block and heads up) should have been reused. Look at the emissions sticker in the engine compartment for vac hose routing, and see if any are disconnected. New plugs should be used. Check to see if the old injectors have the pintle-style tips, if they do, they are 2.8 injectors and are starving the 3.1. The newer style injectors don't have the pintles on the end, they have just a hole, and are called Bosch-style injectors. Replace the o-rings with new ones, GP Sorenson (Advance Auto and AutoZone) part number 800-9220. You will have four left over if you replace the rings on both ends of the injectors, since the kit is for V8 engines. The cold-start injector (the one in the back of the intake) should be connected and used. You do NOT have to mess with the ECM, as with the 3.1 injectors, the engine should still hold close to the same fuel curve.
I have a sample '85 vac diagram, but not on this PC. It's taken from the emissions sticker I currently use, which is attached to a hood I took off of an '85 bird, with the LB8 V6.

BTW, the fuel pressure gauge comes with the Schrader valve attachment already. Just screw it on and take your reading.